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Galileo: en route to full operational capability
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By NASA
On Jan. 7, 1610, Italian astronomer Galileo Galilei peered through his newly improved 20-power homemade telescope at the planet Jupiter. He noticed three other points of light near the planet, at first believing them to be distant stars. Observing them over several nights, he noted that they appeared to move in the wrong direction with regard to the background stars and they remained in Jupiter’s proximity but changed their positions relative to one another. Four days later, he observed a fourth point of light near the planet with the same unusual behavior. By Jan. 15, Galileo correctly concluded that he had discovered four moons orbiting around Jupiter, providing strong evidence for the Copernican theory that most celestial objects did not revolve around the Earth.
Two of Galileo’s telescopes.National Geographic. Painting by Giuseppe Bertini (1858) of Galileo demonstrating his telescope to the Doge of Venice.gabrielevanin.it Page from Galileo’s notebook about his observations of Jupiter’s satellites.University of Michigan Special Collections Library. In March 1610, Galileo published his discoveries of Jupiter’s satellites and other celestial observations in a book titled Siderius Nuncius (The Starry Messenger). As their discoverer, Galileo had naming rights to Jupiter’s satellites. He proposed to name them after his patrons the Medicis and astronomers called them the Medicean Stars through much of the seventeenth century, although in his own notes Galileo referred to them by the Roman numerals I, II, III, and IV, in order of their distance from Jupiter. Astronomers still refer to the four moons as the Galilean satellites in honor of their discoverer.
In 1614, the German astronomer Johannes Kepler suggested naming the satellites after mythological figures associated with Jupiter, namely Io, Europa, Ganymede, and Callisto, but his idea didn’t catch on for more than 200 years. Scientists didn’t discover any more satellites around Jupiter until 1892 when American astronomer E.E. Barnard found Jupiter’s fifth moon Amalthea, much smaller than the Galilean moons and orbiting closer to the planet than Io. It was the last satellite in the solar system found by visual observation – all subsequent discoveries occurred via photography or digital imaging. As of today, astronomers have identified 95 moons orbiting Jupiter.
Image of Jupiter and three of its four Galilean satellites through an amateur telescope, similar to what Galileo might have seen. Hubble Space Telescope image of Jupiter and three of its four Galilean satellites during a rare triple transit. Although each of the Galilean satellites has unique features, such as the volcanoes of Io, the heavily cratered surface of Callisto, and the magnetic field of Ganymede, scientists have focused more attention on Europa due to the tantalizing possibility that it might be hospitable to life. In the 1970s, NASA’s Pioneer 10 and 11 and Voyager 1 and 2 spacecraft took ever increasingly detailed images of the large satellites including Europa during their flybys of Jupiter. The photographs revealed Europa to have the smoothest surface of any object in the solar system, indicating a relatively young crust, and also one of the brightest of any satellite indicating a highly reflective surface. These features led scientists to hypothesize that Europa is covered by an icy crust floating on a subsurface salty ocean. They further postulated that tidal heating caused by Jupiter’s gravity reforms the surface ice layer in cycles of melting and freezing.
Image of Europa taken by Pioneer 10 during its flyby of Jupiter in 1973. Image of Europa taken by Voyager 1 during its 1979 flyby of Jupiter. Image of Europa taken by Voyager 2 during its 1979 flyby of Jupiter. More detailed observations from NASA’s Galileo spacecraft that orbited Jupiter between 1995 and 2003 and completed 11 close encounters with Europa revealed that long linear features on its surface may indicate tidal or tectonic activity. Reddish-brown material along the fissures and in splotches elsewhere on the surface may contain salts and sulfur compounds transported from below the crust and modified by radiation. Observations from the Hubble Space Telescope and re-analysis of images from Galileo revealed possible plumes emanating from beneath Europa’s crust, lending credence to that hypothesis. While the exact composition of this material is not known, it likely holds clues to whether Europa may be hospitable to life.
Global view of Europa from the Galileo spacecraft. More detailed views of varied terrain on Europa from Galileo. Cutaway illustration of Europa’s icy crust, subsurface ocean and possible vents that transport material to the surface. Future robotic explorers of Europa may answer some of the outstanding questions about this unique satellite of Jupiter. NASA’s Europa Clipper set off in October 2024 on a 5.5-year journey to Jupiter. After its arrival in 2030, the spacecraft will enter orbit around the giant planet and conduct 49 flybys of Europa during its four-year mission. Managed by the Jet Propulsion Laboratory in Pasadena, California, and the Applied Physics Laboratory at Johns Hopkins University in Baltimore, Maryland, Europa Clipper will carry nine instruments including imaging systems and a radar to better understand the structure of the icy crust. Data from Europa Clipper will complement information returned by the European Space Agency’s JUICE (Jupiter Icy Moon Explorer) spacecraft. Launched in April 2023, JUICE will first enter orbit around Jupiter in 2031 and then enter orbit around Ganymede in 2034. The spacecraft also plans to conduct studies of Europa complementary with Europa Clipper’s. The two spacecraft should greatly increase our understanding of Europa and perhaps uncover new mysteries.
Illustration of the Europa Clipper spacecraft investigating Europa. Illustration of the JUICE spacecraft exploring Europa.European Space Agency. View the full article
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By Space Force
The inclusion of these C2 centers was a deliberate effort to add a layer of realism and enhance the exercise's effectiveness in preparing joint space forces for the challenges of the Great Power Competition.
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By NASA
Skywatching Home Skywatching The Next Full Moon is the Wolf… Skywatching Home What’s Up Eclipses Explore the Night Sky Night Sky Network More Tips and Guides FAQ 27 Min Read The Next Full Moon is the Wolf Moon
The Moon sets over Homestead National Historic Park in Nebraska. Credits:
National Park Service/Homestead The next full Moon is the Wolf Moon; the Ice or Old Moon; the Moon after Yule; the start of Prayag Kumbh Mela; Shakambhari Purnima; Paush Purnima; the Thiruvathira, Thiruvathirai, or Arudhra Darisanam festival Moon; and Duruthu Poya.
The phases of the Moon for January 2025. NASA/JPL-Caltech The next full Moon will be Monday evening, Jan. 13, 2025, appearing opposite the Sun (in Earth-based longitude) at 5:27 p.m. EST. This will be Tuesday from the South Africa and Eastern European time zones eastward across the remainder of Africa, Europe, Asia, Australia, etc., to the International Date Line in the mid-Pacific. The Moon will appear full for about three days around this time, from Sunday evening (and possibly the last part of Sunday morning) into Wednesday morning. On the night of the full Moon, for most of the continental USA as well as parts of Africa, Canada, and Mexico, the Moon will pass in front of the planet Mars.
The Maine Farmers’ Almanac began publishing Native American names for full Moons in the 1930s. Over time these names have become widely known and used. According to this almanac, as the full Moon in January this is the Wolf Moon, from the packs of wolves heard howling outside the villages amid the cold and deep snows of winter.
European names for this Moon include the Ice Moon, the Old Moon, and (as the full Moon after the winter solstice) the Moon after Yule. Yule was a three to 12-day festival near the winter solstice in pre-Christian Europe. In the tenth century King Haakon I associated Yule with Christmas as part of the Christianization of Norway, and this association spread throughout Europe. The exact timing of this pre-Christian celebration is unclear. Some sources now associate Yule with the 12 days of Christmas, so that the Moon after Yule is after Twelfth Night on January 6. Other sources suggest that Yule is an old name for the month of January, so the Moon after Yule is in February. In the absence of more reliable historic information, I’m going with the full Moon after the winter solstice as the Moon after Yule.
This full Moon corresponds with the start of the 44-day festival Prayag Kumbh Mela, also known as Maha Kumbh. This Hindu pilgrimage and festival is held every 12 years in the Indian city of Prayagraj at the confluence of three rivers, the Ganges, the Yamuna, and the mythical Sarasvati. It is expected to draw around 400 million visitors. Similar Kumbh celebrations are held approximately every 12 years at the convergence of three rivers in three other Indian cities, Nashik (upcoming in 2027), Ujjain (in 2028), and Haridwar (in 2033).
In the Hindu calendar, this full Moon is Shakambhari Purnima, the last day in the 8-day Shakambari Navratri holiday that celebrates the goddess Shakambhari. In the Purnimanta tradition that ends months on the full Moon day, this full Moon is Paush Purnima, the last day of the Hindu month of Paush. The day after Paush Purnima is the start of the month of Magha, a period of austerity. Bathing in the holy waters of India is an important activity for both Shakambari Navratri and Magha.
This full Moon corresponds with the Thiruvathira, Thiruvathirai, or Arudhra Darisanam festival, celebrated by Hindus in the Indian states of Kerala and Tamil Nadu.
For the Buddhists of Sri Lanka, this is Duruthu Poya, which commemorates Siddhartha Gautama Buddha’s first visit to Sri Lanka.
In many lunar and lunisolar calendars the months change with the new Moon and full Moons fall in the middle of the lunar month. This full Moon is in the middle of the 12th and final month of the Chinese Year of the Rabbit. The new Moon on January 29 will be Chinese New Year, the start of the Year of the Snake. This full Moon is in the middle of Tevet in the Hebrew calendar and Rajab, the seventh month of the Islamic calendar. Rajab is one of the four sacred months in which warfare and fighting are forbidden.
As usual, the wearing of suitably celebratory celestial attire is encouraged in honor of the full Moon. Take care in the cold weather and take advantage of these early sunsets to enjoy and share the wonders of the night sky. And avoid starting any wars.
Here are the other celestial events between now and the full Moon after next, with times and angles based on the location of NASA Headquarters in Washington, D.C.:
As winter continues in the Northern Hemisphere, the daily periods of sunlight continue to lengthen. Our 24-hour clock is based on the average length of a day with the solar days near the solstices longer than those near the equinoxes. For Washington, D.C. and similar latitudes (I’ve not checked for other areas) the latest sunrise of the year (ignoring Daylight Saving Time) occurred on January 4. Monday, January 13 (the day of the full Moon), morning twilight will begin at 6:24 a.m. EST, sunrise will be at 7:26 a.m., solar noon will be at 12:17 p.m. when the Sun will reach its maximum altitude of 29.8 degrees, sunset will be at 5:08 p.m., and evening twilight will end at 6:11 p.m. By Wednesday, February 12 (the day of the full Moon after next), morning twilight will begin at 6:04 a.m., sunrise will be at 7:03 a.m., solar noon will be at 12:23 p.m. when the Sun will reach its maximum altitude of 37.7 degrees, sunset will be at 5:43 p.m., and evening twilight will end at 6:41 p.m.
This should be a good time for planet watching, especially with a backyard telescope. Venus, Jupiter, Mars, Saturn, and Uranus will all be in the evening sky. Brightest will be Venus, appearing in the southwestern sky. With a telescope you should be able to see it shift from half-full to a 29% illuminated crescent during this lunar cycle as it brightens and moves closer to the Earth.
Venus will reach its brightest for the year just after the full Moon after next. Second in brightness will be Jupiter in the eastern sky. With a telescope you should be able to see Jupiter’s four bright moons, Ganymede, Callisto, Europa, and Io, noticeably shifting positions in the course of an evening. Jupiter was at its closest and brightest in early December. Third in brightness will be Mars low in the east-northeastern sky. Mars will be at its closest and brightest for the year a few days after this full Moon. Fourth in brightness will be Saturn, appearing near Venus in the southwestern sky. With a telescope you should be able to see Saturn’s bright moon Titan and maybe its rings. The rings are appearing very thin and will be edge-on to the Earth in March 2025. We won’t get the “classic” view of Saturn showing off its rings until 2026. Saturn was at its closest and brightest in early September and will appear its closest to Venus (2.2 degrees apart) the evening of January 18. Fifth in brightness and technically bright enough to see without a telescope (if you are in a very dark location and your eyesight is better than mine) will be Uranus high in the southeastern sky. Uranus was at its closest and brightest in mid-November.
During this lunar cycle these planets will be rotating westward around the pole star Polaris (with Venus shifting more slowly) making them easier to see earlier in the evening, and friendlier for backyard stargazing, especially if you have young ones with earlier bedtimes.
Comets
As mentioned in my last posting, the sungrazing comet C/2024 G3 (ATLAS) will be passing very near the Sun on January 13. There is a chance that this comet will break up and vanish from view as it approaches the Sun, much as comet C/2024 S1 (ATLAS) did in October. In addition, its visual magnitude might not be bright enough to see in the daytime due to the glow of the nearby Sun. If it does not break up and is bright enough, Northern Hemisphere viewers will have the best viewing near its closest approach. For the Washington, D.C. area, it could be brightest the evening of January 12 before it sets on the southwestern horizon. You will need to find a distant object to block direct sunlight so you can safely look about 5 degrees to the upper right of the Sun. If the horizon is very clear, your best chance might be after sunset at 5:07 p.m. EST, but before the comet sets about 10 minutes later. Southern Hemisphere viewers will have the best viewing after closest approach, immediately after sunset from mid-January on (dimming each evening as it moves away from the Sun and the Earth). You may need binoculars or a telescope to see it, although comets are hard to predict.
Meteor Showers
Two minor meteor showers, the γ-Ursae Minorids (404 GUM) and α-Centaurids (102 ACE), will peak during this lunar cycle. The light of the waning Moon will interfere with the γ-Ursae Minorids peak on January 18. The α-Centaurids, only visible from the Southern Hemisphere, are expected to peak on February 8. In recent years the average peak has been 6 visible meteors per hour (under ideal conditions), although this shower showed bursts of 20 to 30 meteors per hour in 1974 and 1980. The best viewing conditions will likely be after the waxing gibbous Moon sets in the early mornings around the peak.
Evening Sky Highlights
On the evening of Monday, Jan. 13, 2025 (the evening of the full Moon), as twilight ends (at 6:11 p.m. EST), the rising Moon will be 13 degrees above the east-northeastern horizon with the bright planet Mars (the third brightest planet) 2 degrees to the lower left and the bright star Pollux (the brighter of the twin stars in the constellation Gemini, the twins) 3 degrees to the upper left of the Moon. The brightest planet visible will be Venus at 29 degrees above the southwestern horizon, with the planet Saturn (fourth brightest) 6 degrees to the upper left of Venus. The second brightest planet, Jupiter, will be 47 degrees above the eastern horizon. The bright star closest to overhead will be Capella at 50 degrees above the east-northeastern horizon. Capella is the 6th brightest star in our night sky and the brightest star in the constellation Auriga (the charioteer). Although we see Capella as a single star it is actually four stars (two pairs of stars orbiting each other). Capella is about 43 light years from us.
As this lunar cycle progresses, the planets and the background of stars will appear to rotate westward around the pole star Polaris each evening, with Venus initially shifting the other direction. Mars will be at its closest and brightest on January 15. Venus and Saturn will appear closest to each other on January 18. Mars and Pollux will appear nearest each other on January 22 and 23. Venus will appear at its highest above the horizon (as twilight ends) on January 27, after which it will start shifting toward the horizon again. Jupiter and Aldebaran will appear at their closest on January 31. The waxing Moon will pass by Saturn on January 31; Venus on February 1; the Pleiades star cluster on February 5; and Mars and Pollux on February 10.
By the evening of Wednesday, February 12 (the evening of the full Moon after next), as twilight ends (at 6:41 p.m. EST), the rising Moon will be 7 degrees above the east-northeastern horizon with the bright star Regulus 2 degrees to the right. The brightest planet in the sky will be Venus at 28 degrees above the west-southwestern horizon, appearing as a crescent through a telescope. Next in brightness will be Jupiter at 71 degrees above the south-southeastern horizon. Third in brightness will be Mars at 48 degrees above the eastern horizon. Saturn will be 11 degrees above the west-southwestern horizon. Uranus, on the edge of what is visible under extremely clear, dark skies, will be 68 degrees above the south-southwestern horizon. The bright star closest to overhead will still be Capella at 75 degrees above the northeastern horizon.
Also high in the sky will be the constellation Orion, easily identifiable because of the three stars that form Orion’s Belt. This time of year, we see many bright stars in the sky at evening twilight, with bright stars scattered from the south-southeast toward the northwest. We see more stars in this direction because we are looking toward the Local Arm of our home galaxy (also called the Orion Arm, Orion-Cygnus Arm, or Orion Bridge). This arm is about 3,500 light years across and 10,000 light years long. Some of the bright stars we see from this arm are the three stars of Orion’s Belt, as well as Rigel (860 light years from Earth), Betelgeuse (548 light years), Polaris (about 400 light years), and Deneb (about 2,600 light years).
Facing toward the south from the northern hemisphere, to the upper left of Orion’s Belt is the bright star Betelgeuse (be careful not to say this name three times). About the same distance to the lower right is the bright star Rigel. Orion’s belt appears to point down and to the left about seven belt lengths to the bright star Sirius, the brightest star in the night sky. Below Sirius is the bright star Adara. To the upper right of Orion’s Belt (at about the same distance from Orion as Sirius) is the bright star Aldebaran. Nearly overhead is the bright star Capella. To the left (east) of Betelgeuse is the bright star Procyon. The two stars above Procyon are Castor and Pollux, the twin stars of the constellation Gemini (Pollux is the brighter of the two). The bright star Regulus appears farther to the left (east) of Pollux near the eastern horizon. Very few places on the East Coast are dark enough to see the Milky Way (our home galaxy), but if you could see it, it would appear to stretch overhead from the southeast to the northwest. Since we are seeing our galaxy from the inside, the combined light from its 100 billion to 400 billion stars make it appear as a band surrounding the Earth.
Morning Sky Highlights
On the morning of Monday, Jan. 13, 2025 (the morning of the full Moon), as twilight begins (at 6:23 a.m. EST), the setting full Moon will be 11 degrees above the west-northwestern horizon. This will be the last morning the planet Mercury will rise before morning twilight begins, although it will be bright enough to see in the glow of dawn after it rises for another week or so. This will leave Mars at 18 degrees above the west-northwestern horizon as the only planet in the sky. The bright star appearing closest to overhead will be Arcturus at 69 degrees above the south-southeastern horizon. Arcturus is the brightest star in the constellation Boötes (the herdsman or plowman) and the 4th brightest star in our night sky. It is 36.7 light years from us. While it has about the same mass as our Sun, it is about 2.6 billion years older and has used up its core hydrogen, becoming a red giant 25 times the size and 170 times the brightness of our Sun. One way to identify Arcturus in the night sky is to start at the Big Dipper, then follow the arc of the dipper’s handle as it “arcs toward Arcturus.”
As this lunar cycle progresses Mars and the background of stars will appear to rotate westward around the pole star Polaris by about 1 degree each morning. The waning Moon will appear near Mars and Pollux on January 13 and 14, Regulus on January 16, Spica on January 21, Antares on January 24 and 25, and (rising after morning twilight begins) Mercury on January 28. January 22 will be the last morning the planet Mercury will be above the horizon 30 minutes before sunrise. Mars and Pollux will be near their closest to each other the morning of January 23. February 4 will be the last morning the planet Mars will be above the northwestern horizon as morning twilight begins. The waxing Moon will appear near Pollux on February 9 (setting before twilight begins) and 10.
By the morning of Wednesday, February 12 (the morning of the full Moon after next), as twilight begins (at 6:04 a.m. EST), the setting full Moon will be 13 degrees above the western horizon. No planets will appear in the sky. The bright star appearing closest to overhead will still be Arcturus at 65 degrees above the southeastern horizon.
Detailed Daily Guide
Here is a day-by-day listing of celestial events between now and the full Moon on Feb. 12, 2025. The times and angles are based on the location of NASA Headquarters in Washington, D.C., and some of these details may differ for where you are (I use parentheses to indicate times specific to the D.C. area). If your latitude is significantly different than 39 degrees north (and especially for my Southern Hemisphere readers), I recommend using an astronomy app set for your location or a star-watching guide from a local observatory, news outlet, or astronomy club.
Tuesday evening, January 7 At 7:07 p.m. EST, the Moon will be at perigee, its closest to the Earth for this orbit.
Thursday evening, January 9 The waxing gibbous Moon will pass in front of the Pleiades star cluster. This may be viewed best with binoculars, as the brightness of the Moon will make it hard to see the stars in this star cluster. As evening twilight ends at 6:07 p.m. EST, the Pleiades will appear 1 degree to the lower left of the full Moon. Over the next few hours, including as the Moon reaches its highest for the night at 8:37 p.m., the Moon will pass in front of the Pleiades, blocking many of these stars from view. By about midnight the Pleiades will appear about 1 degree below the Moon, and the Moon and the Pleiades will separate as Friday morning progresses.
Also on Thursday night, January 9, the planet Venus will reach its greatest angular separation from the Sun as seen from the Earth for this apparition (called greatest elongation). Because the angle between the line from the Sun to Venus and the line of the horizon changes with the seasons, the date when Venus and the Sun appear farthest apart as seen from Earth is not always the same as when it appears highest above the west-southwestern horizon as evening twilight ends, which occurs on January 27.
Friday evening, January 10 The bright planet Jupiter will appear near the waxing gibbous Moon. As evening twilight ends at 6:08 p.m. EST, Jupiter will be 5 degrees to the lower right. As the Moon reaches its highest for the night at 9:37 p.m., Jupiter will be 6 degrees below the Moon. The pair will continue to separate until Jupiter sets Saturday morning at 4:45 a.m.
Sunday afternoon, January 12 There is a slight chance that the sungrazing comet, C/2024 G3 (ATLAS) might be visible near the setting Sun. Most likely, this comet will not be bright enough to see in the daytime or will break up and vanish from view like comet C/2024 S1 (ATLAS) did in October. The odds are low, but if the sky is clear, find an object to block direct sunlight (the farther away the object the better) so you can safely look about 5 degrees to the upper right of the Sun. If the west-southwestern horizon is clear, your best chance might be after sunset at 5:07 p.m. EST, but before the comet sets about 10 minutes later. This will only be visible from the Northern Hemisphere. Southern Hemisphere viewers may be able to see this comet from mid-January on immediately after sunset (dimming each evening as it moves away from us).
Monday morning, January 13 This is the morning of the full Moon. It will be the last morning Mercury will rise before morning twilight begins, although it will be bright enough to see in the glow of dawn after it rises for another week or so.
The Moon will be full Monday evening at 5:27 p.m. EST. This will be on Tuesday from the South Africa and Eastern European time zones eastward across the rest of Africa, Europe, Asia, Australia, etc., to the International Date Line in the mid-Pacific. The Moon will appear full for about three days around this time, from Sunday evening (and possibly the last part of Sunday morning) into Wednesday morning.
On Monday night the full Moon will appear near and pass in front of the bright planet Mars, with the bright star Pollux above the pair. As evening twilight ends at 6:11 p.m. EST, the three will form a triangle, with Mars 2 degrees to the lower left and Pollux 3 degrees to the upper left of the Moon. For most of the continental USA as well as parts of Africa, Canada, and Mexico, the Moon will pass in front of Mars. Times will vary for other locations, but for NASA Headquarters in Washington, D.C., Mars will vanish behind the bottom of the Moon at about 9:16 p.m. and reappear from behind the upper right of the Moon at about 10:31 p.m. By the time the Moon reaches its highest for the night early on Tuesday morning at 12:37 a.m., Mars will be 1 degree to the right of the Moon and Pollux 5 degrees to the upper right. As morning twilight begins at 6:23 a.m., Mars will be 4 degrees and Pollux 8 degrees to the lower right of the Moon.
Wednesday night January 15 The planet Mars will be at opposition, so called because it will be opposite the Earth from the Sun, effectively a “full” Mars. Near opposition Mars will be at its closest and brightest for the year. On Wednesday night, as evening twilight ends at 6:13 p.m. EST, Mars will be 14 degrees above the east-northeastern horizon. Mars will reach its highest in the sky early Thursday morning at 12:21 a.m., and will be 15 degrees above the west-northwestern horizon as morning twilight begins at 6:23 a.m. Only planets that orbit farther from the Sun than the Earth can be seen at opposition from the Earth.
Wednesday night into Thursday morning, January 15 to 16 The bright star Regulus will appear near the waning gibbous Moon. As Regulus rises on the east-northeastern horizon at 7:52 p.m. EST, it will be more than 8 degrees below the Moon. By the time the Moon reaches its highest for the night on Thursday morning at 2:17 a.m. Regulus will be 5.5 degrees to the lower left of the Moon. As morning twilight begins at 6:23 a.m. Regulus will be 4 degrees to the left of the Moon.
Saturday evening, January 18 Venus and Saturn will appear nearest to each other. As evening twilight ends at 6:15 p.m. EST, Venus will be 30 degrees above the southwestern horizon with Saturn 2.2 degrees to the lower left. Saturn will set first on the western horizon almost 3 hours later at 9:04 p.m.
Monday night, January 20 At 11:53 p.m. EST, the Moon will be at apogee, its farthest from the Earth for this orbit.
Tuesday morning, January 21 The bright star Spica will appear near the waning gibbous Moon. As the Moon rises on the east-southeastern horizon at 12:11 a.m. EST Spica will be 1 degree above the Moon. By the time the Moon reaches its highest for the night at 5:41 a.m., Spica will be 3.5 degrees to the upper right, with morning twilight beginning 40 minutes later at 6:21 a.m. For parts of Western Africa and the Atlantic Ocean the Moon will pass in front of Spica.
Tuesday afternoon, the waning Moon will appear half-full as it reaches its last quarter at 3:31 p.m. EST (when we can’t see it).
Wednesday morning, January 22 This will be the last morning Mercury will be above the horizon 30 minutes before sunrise, an approximation of the last morning it might be visible in the glow of dawn.
Throughout this lunar cycle, Mars and the bright star Pollux will appear near each other, with Wednesday night into Thursday morning and Thursday night into Friday morning (January 22, 23, and 24) the nights when they will be at their closest, 2.5 degrees apart. They will be up all night for both nights, with Mars at its highest on Wednesday night at 11:41 p.m. EST, and Thursday night at 11:36 p.m.
Friday morning, January 24 The bright star Antares will appear to the lower left of the waning crescent Moon. As Antares rises on the southeastern horizon at 3:54 a.m. EST, it will be 8 degrees from the Moon. By the time morning twilight begins less than 2.5 hours later at 6:19 a.m., Antares will be 6.5 degrees from the Moon. For part of the Indian Ocean the Moon will actually pass in front of Pollux.
Saturday morning, January 25 The Moon will have shifted to the other side of Antares. As the Moon rises at 4:20 a.m. EST, Antares will be 6 degrees to the upper right of the Moon. By the time morning twilight begins 2 hours later at 6:19 a.m., Antares will be 7 degrees from the Moon.
Monday evening, January 27 Venus will be at its highest above the west-southwestern horizon (31 degrees) as evening twilight ends at 6:25 p.m. EST, appearing as a 41% illuminated crescent through a telescope.
Wednesday morning, January 29 At 7:36 a.m. EST there will be a new Moon, when the Moon passes between the Earth and the Sun, and the Moon will not be visible from the Earth. The day of, or the day after, the New Moon marks the start of the new month for most lunisolar calendars. The first month of the Chinese calendar starts on Wednesday, January 29, making this Chinese New Year, the start of the Year of the Snake! Chinese New Year and related celebrations throughout much of Asia and in areas with significant Chinese populations celebrate the end of winter and start of spring. Traditional festivities start on the eve of Chinese New Year and continue until the Lantern Festival on the 15th day of the first lunar month.
Sundown on Wednesday, January 29 This marks the start of Shevat in the Hebrew calendar.
Sundown on Thursday, January 30 In the Islamic calendar, the months traditionally start with the first sighting of the waxing crescent Moon. Many Muslim communities now follow the Umm al-Qura Calendar of Saudi Arabia, which uses astronomical calculations to start months in a more predictable way. Using this calendar, sundown on Thursday, January 30, will probably mark the beginning of Shaʿbān, the eighth month of the Islamic year and the month before Ramadan.
Friday evening, January 31 Saturn will appear 4 degrees to the upper left of the waxing crescent Moon. The Moon will be 17 degrees above the west-southwestern horizon as evening twilight ends at 6:29 p.m. EST, and will set on the western horizon 99 minutes later at 8:08 p.m. For part of Asia the Moon will actually pass in front of Saturn.
Throughout this lunar cycle the bright star Aldebaran will appear below the bright planet Jupiter, with Friday, January 31 the evening they appear at their closest, about 5 degrees apart. As evening twilight ends at 6:29 p.m. EST, Jupiter will be 65 degrees above the southeastern horizon with Aldebaran to the lower right. Jupiter will reach its highest for the night, 73 degrees above the southern horizon at 8:01 p.m., with Aldebaran below Jupiter. As Aldebaran sets on the west-northwestern horizon almost 7 hours after that at 2:56 a.m. it will be to the lower left of the Moon.
Saturday evening, February 1 Venus will appear near the waxing crescent Moon. The Moon will be 30 degrees above the west-southwestern horizon as evening twilight ends at 6:30 p.m. EST, with Venus 2.5 degrees to the upper right. Venus will be 2.5 degrees to the lower right as it sets first on the western horizon 2.75 hours later at 9:15 p.m.
Saturday night, at 9:38 p.m. EST, the Moon will be at perigee, its closest to the Earth for this orbit.
Saturday also is Imbolc or Imbolg, and the next day (Sunday, February 2) is Candlemas or Groundhog’s Day. We currently divide the year into four seasons based upon the solstices and equinoxes, with spring starting on the vernal equinox. This approximates winter as the quarter of the year with the coldest temperatures. Much of pre-Christian northern Europe celebrated “cross-quarter days” halfway between the solstices and equinoxes, dividing the seasons on these days. Using this definition, winter was the quarter of the year with the shortest daily periods of daylight, and spring started on Imbolc (the middle of our winter).
The tradition in some European countries was to leave Christmas decorations up until February 1st, the eve of Candlemas, and it was considered bad luck to leave decorations up past this date. Robert Herrick (1591-1674) starts his poem “Ceremonies for Candlemas Eve” with “Down with the rosemary and bays, down with the mistletoe; Instead of holly, now up-raise the greener box (for show).”
We have a tradition in the United States that winter will end on Groundhog Day if the groundhog sees its shadow. If not, winter will last six weeks more (ending around the time of the spring equinox). Groundhog Day appears to tie back to European lore about whether or not badgers, wolves, or bears (instead of groundhogs) see their shadows. Many believe that these Groundhog Day and Candlemas traditions tie back to these earlier celebrations for the start of spring. It seems plausible to me that it was confusing to have two competing dates for the end of winter. Perhaps it was best to let a natural event such as an animal’s shadow decide which definition to use, rather than arguing with your neighbors for the next six weeks.
Tuesday morning, February 4 This will be the last morning Mars will be above the northwestern horizon as morning twilight begins.
Wednesday morning, February 5 The Moon will appear half-full as it reaches its first quarter at 3:02 a.m. EST (when we can’t see it).
Wednesday evening the waxing gibbous Moon will appear near the Pleiades star cluster. As evening twilight ends at 6:34 p.m. EST, this star cluster will be 5 degrees to the upper left of the Moon. The Pleiades will shift closer toward the Moon until the Moon sets on the west-northwestern horizon less than 8 hours later at 2:16 a.m. Some North American locations farther west will actually see the Moon pass in front of some of the stars in the Pleiades.
Sunday morning, February 9 Mars will appear to the upper left of the waxing gibbous Moon. In the early morning at about 2 a.m. EST, Mars will be 8 degrees from the Moon. By the time the Moon sets on the northwestern horizon at 5:58 a.m., Mars will have shifted to 6 degrees from the Moon. For parts of Asia and Northern Europe the Moon will pass in front of Mars.
Also Sunday morning, Mercury will be passing on the far side of the Sun as seen from the Earth, called superior conjunction. Because Mercury orbits inside of the orbit of Earth it will be shifting from the morning sky to the evening sky and will begin emerging from the glow of dusk on the west-southwestern horizon after about February 17 (depending upon viewing conditions).
Sunday evening into Monday morning, February 9 to 10 The waxing gibbous Moon will have shifted to the other side of Mars (having passed in front of Mars in the afternoon when we could not see them). As evening twilight ends at 6:38 p.m. EST, the Moon will be between Mars and the bright star Pollux, with Mars 3 degrees to the upper right and Pollux 3 degrees to the lower left. By the time the Moon reaches its highest for the night at 10:27 p.m., Mars will be 4.5 degrees to the right of the Moon and Pollux 2.5 degrees to the upper left of the Moon. Mars will set first on the northwestern horizon Monday morning at 5:44 a.m. just 22 minutes before morning twilight begins at 6:06 a.m.
Wednesday morning, February 12 The full Moon after next will be at 8:53 a.m. EST, with the bright star Regulus nearby. This will be on Thursday morning from Australian Central Time eastward to the International Date Line in the mid-Pacific. The Moon will appear full for about three days around this time, from Monday night into early Thursday evening.
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SkywatchingHome The Next Full Moon is the Cold… Skywatching Skywatching Home What’s Up Eclipses Explore the Night Sky Night Sky Network MoreTips and Guides FAQ 31 Min Read The Next Full Moon is the Cold Moon
A full Moon rising over the Wasatch Mountains in Utah on March 15, 2014. Credits: NASA/Bill Dunford The Next Full Moon is the Cold Moon, Frost Moon, or the Winter Moon; the Moon before Yule or the Oak Moon; the Long Night Moon; the Child Moon; the Datta or Dattatreya Jayanti Festival Moon; the Karthika Deepam Festival Moon; Unduvap Poya; and the Chang’e Moon.
The next full Moon will be Sunday morning, Dec. 15, 2024, passing opposite the Sun at 4:02 a.m. EST. This will be Saturday evening from Alaska Time westwards to the International Date Line. The Moon will appear full for about three days around this time, from Friday evening through Monday morning, making this a full Moon weekend.
The Maine Farmers’ Almanac began publishing Native American names for full Moons in the 1930s. Over time these names have become widely known and used. According to this almanac, as the full Moon in December this is the Cold Moon, due to the long, cold nights. Other names are the Frost Moon (for the frosts as winter nears) or the Winter Moon.
As the full Moon before the winter solstice, old European names for this Moon include the Moon before Yule and the Oak Moon. Yule was a three-day winter solstice festival in pre-Christian Europe. In the 10th century King Haakon I associated Yule with Christmas as part of the Christianization of Norway, and this association spread throughout Europe. Some believe that the Oak Moon name ties back to ancient druid traditions of harvesting mistletoe from oak trees, a practice first recorded by the Roman historian Pliny the Elder in the first century CE. The term “druid” may derive from the Proto-Indo-European roots for “oak” and “to see,” suggesting “druid” means “oak knower” or “oak seer.”
As the full Moon closest to the winter solstice, this will be the Long Night Moon. The plane of the Moon’s orbit around Earth nearly matches the plane of Earth’s orbit around the Sun. When the path of the Sun appears lowest in the sky for the year, the path of the full Moon opposite the Sun appears near its highest. For the Washington, D.C. area, on Saturday evening into Sunday morning, December 14 to 15, the Moon will be in the sky for a total of 16 hours 1 minute and will reach a maximum altitude of 79.0 degrees (at 11:52 p.m. EST), with 14 hours 33 minutes of this when the Sun is down. The next night, Sunday evening into Monday morning, December 15 to 16, the full Moon will be in the sky slightly longer and will reach higher in the sky, but slightly less of this time will be when the Sun is down. The Moon will be in the sky for a total of 16 hours 3 minutes and will reach a maximum altitude of 79.2 degrees (at 1:54 a.m.), with 14 hours 29 minutes of this when the Sun is down.
This also is the Child Moon. Five years ago, then 7-year-old Astrid Hattenbach was walking home from school with her father Henry Throop (a friend and former coworker at NASA Headquarters). When she saw the rising full Moon, she said: “You know what this Moon is called? It’s called a Child Moon. Because the Moon rises at a time that the children, they can see it, because they’re not in bed, and they might even be outside like we are right now.” Henry told me about this and I thought it a perfect name. This year (at least for Washington, D.C. and similar latitudes), the earliest evenings with a full Moon in the sky will be on December 13 through 15, with sunset at 4:44 p.m. EST and evening twilight ending at 5:50 p.m. (on the 13th) or 5:51 p.m. (on the 14th and 15th). For more on the wonder the Moon imbues in the hearts of children (and in all of us) look up Carl Sandburg’s poem “Child Moon.”
For Hindus, this full Moon corresponds with Datta Jayanti, also known as Dattatreya Jayanti, a festival commemorating the birth day of the Hindu god Dattatreya (Datta), celebrated on the full Moon day of the month of Margashira.
Karthika Deepam is a festival observed by Hindus of Tamil Nadu, Sri Lanka, and Kerala when the nearly full Moon lines up with the Pleiades constellation (Krittikai or Karttikai). This year it will be on Friday, December 13. Some areas celebrate multi-day festivals that include this full Moon.
For the Buddhists of Sri Lanka, this is Unduvap Poya. In the third century BCE, Sangamitta Theri, the daughter of Emperor Ashoka and founder of an order of Buddhist nuns in Sri Lanka, is believed to have brought a sapling of the sacred Bodhi Tree, or Bo Tree, to Sri Lanka. The sapling was planted in 288 BCE by King Devanampiya Tissa in the Mahamevnāwa Park in Anuradhapura where it still grows today, where it is believed by some to be the oldest living human-planted tree with a known planting date.
We could also call this the Chang’e Moon, after the three Chinese lunar landers that launched and landed on the Moon this time of year. These missions get their name from the Chinese goddess of the Moon, Chang’e, who lived on the Moon with her pet rabbit, Yutu. The Chang’e 3 lander and its companion Yutu rover launched on Dec. 1, 2013, and landed on the Moon a few days later on December 14. The Chang’e 4 lander and Yutu-2 rover launched Dec. 7, 2018, and landed on the Moon on Jan. 3, 2019. The Chang’e 5 lunar sample return mission was launched in 2020 on November 23 (in UTC, November 24 in China’s time zone), collected samples from the Moon, and returned them to Earth on Dec. 16, 2020, humanity’s first lunar sample return since 1976. The Chang’e 6 lunar sample return mission ended the “streak” of December missions by launching on May 3, collecting samples from the Moon, and returning them to Earth on June 25, 2024, humanity’s first lunar sample return from the far side of the Moon.
In many traditional Moon-based calendars the full Moons fall on or near the middle of each month. This full Moon is near the middle of the eleventh month of the Chinese year of the Dragon and Jumādā ath-Thāniyah, also known as Jumādā al-ʾĀkhirah, the sixth month of the Islamic year. This full Moon is the middle of Kislev in the Hebrew calendar. Hanukkah begins on the 25th of Kislev (starting this year with sundown on December 25) and ends 8 days later (with sundown on January 2).
As usual, the wearing of suitably celebratory celestial attire is encouraged in honor of the full Moon. Bundle up for the cold, then take advantage of these early nightfalls to admire the sky, Moon, planets, and stars!
Here are other celestial events between now and the full Moon after next with specific times and angles based on the location of NASA Headquarters in Washington, D.C.:
For the Northern Hemisphere, as autumn ends and winter begins, the daily periods of sunlight reach their shortest at the winter solstice and then begin to lengthen again. Our 24-hour clock is based on the average length of the solar day. The winter solstice has the longest night of the year. The winter solstice is sometimes called the “shortest day of the year” (because it has the shortest period of sunlight), but the solar days near the solstice are actually the longest. Because of this, the earliest sunset of the year occurs before the solstice (on December 6 and 7 for the Washington, D.C. area) and the latest sunrise of the year (ignoring Daylight Savings Time) occurs after the solstice on Jan. 4, 2025.
On Sunday, December 15, (the day of the full Moon), morning twilight will begin at 6:16 a.m. EST, sunrise will be at 7:20 a.m., solar noon will be at 12:04 p.m. when the Sun will reach its maximum altitude of 27.8 degrees, sunset will be at 4:47 p.m., and evening twilight will end at 5:51 p.m.
Saturday, December 21, will be the day of the Northern Hemisphere winter solstice, the astronomical end of fall and start of winter. The winter solstice is the day when the Sun at solar noon is lowest in the sky and the time from sunrise to sunset is shortest for the year. At NASA Headquarters, the time from sunrise to sunset will be 9 hours, 26 minutes, 13 seconds. Solar noon will be at 12:07 p.m. EST when the Sun will reach its lowest daily high, 27.7 degrees. The longest solar day (measured from noon to noon on a sundial) will be from solar noon on December 21 to solar noon on December 22, 29.8 seconds longer than 24 hours.
By Monday, Jan. 13, 2025 (the day of the full Moon after next), morning twilight will begin at 6:24 a.m. EST, sunrise will be at 7:26 a.m., solar noon will be at 12:17 p.m. when the Sun will reach its maximum altitude of 29.8 degrees, sunset will be at 5:08 p.m., and evening twilight will end at 6:11 p.m.
This will still be a good time for Jupiter and Saturn watching, especially with a backyard telescope. Saturn was at its closest and brightest on September 7 and Jupiter on December 7. With clear skies and a telescope, you should be able to see Jupiter’s four bright moons, Ganymede, Callisto, Europa, and Io, noticeably shifting positions in the course of an evening. For Saturn, you should be able to see Saturn’s rings and its bright moon Titan. The rings are appearing thinner and will be edge-on to Earth in March 2025. We won’t get the “classic” view of Saturn showing off its rings until 2026. During this lunar cycle both of these planets will be shifting towards the west, making them easier to see earlier in the evening sky (and friendlier for backyard stargazing, especially if you have young ones with earlier bedtimes). During this lunar cycle, as twilight ends each evening, Saturn will be shifting from 43 degrees above the southern horizon to 33 degrees above the southwestern horizon while Jupiter will be shifting from 19 degrees above the east-northeastern horizon to 47 degrees above the eastern horizon.
Comets
Sungrazing comet C/2024 G3 (ATLAS) was discovered in April 2024. It will be passing very near the Sun and might be bright enough to see in the daytime for a short time around its closest approach to the Sun on January 13. The Southern Hemisphere will have the best viewing before and after closest approach (probably requiring binoculars or a telescope), while the Northern Hemisphere will have the best viewing near closest approach. Most likely, this comet will break up and vanish from view as it approaches the Sun like comet C/2024 S1 (ATLAS) did in October. There is only a slight chance that it might survive long enough to be visible near its closest approach. In addition, its visual magnitude might not be bright enough to see in the glow of the nearby Sun.
For the Washington, D.C. area, assuming this comet follows its current brightness curve and doesn’t disintegrate, it should be at its brightest the evening of January 12 just before it sets on the southwestern horizon. It will be about 5 degrees to the upper right of the setting Sun. If the horizon is very clear, your best chance of seeing this comet might be after sunset at 5:07 p.m. EST, but before the comet sets about 10 minutes later.
Meteor Showers
Three meteor showers, the Comae Berenicids (020 COM), the Ursids (015 URS), and the Quadrantids (010 QUA), are expected to peak during this lunar cycle. The Comae Berenicids are a weak but long-lasting shower that will be adding slightly to the background rate of meteors. Under ideal conditions near its peak on December 16 it can produce about 3 visible meteors per hour, but this year moonlight will interfere.
The Ursids are expected to peak on the morning of December 22. The MeteorActive app predicts that under bright suburban conditions this shower will only add 1 or 2 meteors per hour to the background rate. On rare occasions this shower can produce major outbursts, as it did in 1945 and 1986 (other outbursts may have been missed due to weather). The International Meteor Organization reports this shower is poorly observed with a narrow peak that seems to fluctuate each year. The radiant for this shower (the point the meteors appear to radiate out from) is high in the northern sky, so this shower can be seen all night from most of the Northern Hemisphere but is not visible from the Southern Hemisphere. This year the Moon will be near its last quarter so the best time to look should be the evenings of December 21 and December 22, between when the sky is completely dark and moonrise. These meteors are caused by debris from the comet 8P/Tuttle entering Earth’s atmosphere at 74,000 mph (33 kilometers per second).
The Quadrantids will be active from Dec. 28, 2024 to Jan. 12, 2025. While this is one of the three major annual Northern Hemisphere showers, its narrow peak means it can be difficult to see. This shower radiates out from a point that passes directly over 49 degrees north. It is predicted to have a peak about 4 hours wide centered around 10 a.m. EST on January 3 (when we can’t see them from the Washington, D.C. area). For the D.C. area the MeteorActive app predicts that at about 6 a.m. on the morning of January 3, under bright suburban sky conditions, the peak visible rate from the Quadrantids and all other background sources might reach 14 meteors per hour. Going to a nearby dark sky area (like Sky Meadows State Park in Virginia) might get these rates up to about 34 meteors per hour. Viewing should be better farther west (where the sky will be dark closer to the peak), with the peak viewing probably somewhere in the northern Pacific Ocean. These meteors are caused by debris entering Earth’s atmosphere at 92,000 mph (41 kilometers per second). The source of the debris is uncertain but might be the minor planet 2003 EH1, which in turn may be related to the comet C/1490 Y1 observed by Chinese, Japanese, and Korean astronomers in 1490.
If you do go out looking for these meteors, be sure to give your eyes plenty of time to adapt to the dark. Your color-sensing cone cells are concentrated near the center of your view with the more sensitive rod cells on the edge of your view. Since some meteors are faint, you will tend to see more meteors from the “corner of your eye” (which is why you need to view a large part of the sky). Your color vision (cone cells) will adapt to darkness in about 10 minutes, but your night vision rod cells will continue to improve for an hour or more (with most of the improvement in the first 35 to 45 minutes). The more sensitive your eyes are, the more chance you have of seeing meteors. Even a short exposure to light (from passing car headlights, etc.) will start the adaptation over again (so no turning on a light or your cell phone to check what time it is).
Evening Sky Highlights
On the evening of Saturday, December 14 (the start of the night of the full Moon), as twilight ends (at 5:50 p.m. EST), the rising Moon will be 19 degrees above the east-northeastern horizon with bright planet Jupiter 6 degrees to the right and the bright star Aldebaran father to the right. The brightest planet visible will be Venus at 21 degrees above the southwestern horizon. Next in brightness will be Jupiter. Saturn will be 43 degrees above the southern horizon. The bright star closest to overhead will be Deneb at 61 degrees above the west-northwestern horizon. Deneb (visual magnitude 1.3) is the 19th brightest star in our night sky and is the brightest star in the constellation Cygnus the swan. It is one of the three bright stars of the “Summer Triangle” (along with Vega and Altair). Deneb is about 20 times more massive than our Sun but has used up its hydrogen, becoming a blue-white supergiant about 200 times the diameter of the Sun. If Deneb were where our Sun is, it would extend to about the orbit of Earth. Deneb is about 2,600 light years from us.
As this lunar cycle progresses, Jupiter, Saturn and the background of stars will appear to rotate westward around Polaris the pole star each evening (as Earth moves around the Sun). Bright Venus will shift to the left and higher in the sky along the southwestern horizon towards Saturn. January 4 will be the first evening Mars will be above the horizon as twilight ends. The waxing Moon will pass by Venus on January 3, Saturn on January 4, in front of the Pleiades star cluster on January 9, and Jupiter on January 10. On January 12 there is a very slight chance that the sungrazing comet, C/2024 G3 (ATLAS) (discovered in April 2024) might be visible 5 degrees to the upper right of the setting Sun.
By the evening of Monday, Jan. 13, 2025 (the evening of the full Moon after next), as twilight ends (at 6:11 P.M. EST), the rising Moon will be 13 degrees above the east-northeastern horizon with the bright planet Mars (the third brightest planet) 2 degrees to the lower left and the bright star Pollux (the brighter of the twin stars in the constellation Gemini the twins) 3 degrees to the upper left of the Moon. The brightest planet visible will be Venus at 29 degrees above the southwestern horizon, with the planet Saturn (fourth brightest) 6 degrees to the upper left of Venus. The second brightest planet, Jupiter, will be 47 degrees above the eastern horizon. The bright star closest to overhead will be Capella at 50 degrees above the east-northeastern horizon. Capella is the 6th brightest star in our night sky and the brightest star in the constellation Auriga the charioteer. Although we see Capella as a single star it is actually four stars (two pairs of stars orbiting each other). Capella is about 43 light-years from us.
Morning Sky Highlights
On the morning of Sunday, December 15 (the morning of the full Moon), as twilight begins (at 6:16 AM EST), the setting full Moon will be 15 degrees above the west-northwestern horizon. The brightest planet in the sky will be Jupiter, appearing below the Moon at 5 degrees above the horizon. Second in brightness will be Mars at 46 degrees above the western horizon, then Mercury at 4 degrees above the east-southeastern horizon. The bright star appearing closest to overhead will be Regulus at 55 degrees above the southwestern horizon, with Arcturus a close second at 52 degrees above the east-southeastern horizon. Regulus is the 21st brightest star in our night sky and the brightest star in the constellation Leo the lion. The Arabic name for Regulus translates as “the heart of the lion.” Although we see Regulus as a single star, it is actually four stars (two pairs of stars orbiting each other). Regulus is about 79 light years from us. Arcturus is the brightest star in the constellation Boötes the herdsman or plowman and the 4th brightest star in our night sky. It is 36.7 light years from us. While it has about the same mass as our Sun, it is about 2.6 billion years older and has used up its core hydrogen, becoming a red giant 25 times the size and 170 times the brightness of our Sun. One way to identify Arcturus in the night sky is to start at the Big Dipper, then follow the arc of the dipper’s handle as it “arcs towards Arcturus.”
As this lunar cycle progresses, Jupiter, Mars, and the background of stars will appear to rotate westward around Polaris the pole star each morning. Mercury too will appear to shift in the same general direction until December 23, after which it will start shifting towards the horizon again. After December 20 Jupiter will no longer be above the horizon as twilight begins. The waning Moon will pass by Pollux on December 17, Mars on December 18, Regulus on December 20, Spica on December 24, and Antares on December 28. Around 6 a.m. on January 3 will likely be the best time to look for the Quadrantids meteor shower. Under suburban conditions it might produce 14 visible meteors per hour.
By the morning of Monday, Jan. 13, 2025 (the morning of the full Moon after next), as twilight begins at 6:23 a.m. EST, the setting full Moon will be 11 degrees above the west-northwestern horizon. This will be the first morning the planet Mercury will rise after morning twilight begins (although it will be bright enough to see in the glow of dawn after it rises) leaving Mars at 18 degrees above the west-northwestern horizon the only planet in the sky. The bright star appearing closest to overhead will be Arcturus at 69 degrees above the south-southeastern horizon.
Detailed Daily Guide
Here is a day-by-day listing of celestial events between now and the full Moon on Jan. 13, 2025. The times and angles are based on the location of NASA Headquarters in Washington, D.C., and some of these details may differ for where you are (I use parentheses to indicate times specific to the D.C. area). If your latitude is significantly different than 39 degrees north (and especially for my Southern Hemisphere readers), I recommend using an astronomy app set for your location or a star-watching guide from a local observatory, news outlet, or astronomy club.
Thursday morning, December 12 The first morning the planet Mercury will be above the east-southeastern horizon as morning twilight begins (at 6:14 a.m. EST). Also, on Thursday morning at 8:28 a.m., the Moon will be at perigee, its closest to Earth for this orbit.
Friday evening into Saturday morning, December 13 to 14 The Pleiades star cluster will appear near the full Moon. This may best be viewed with binoculars, as the brightness of the full Moon may make it hard to see the stars in this star cluster. As evening twilight ends at 5:50 p.m. EST, the Pleiades will appear 4 degrees to the upper right of the full Moon. By the time the Moon reaches its highest for the night at 10:49 p.m., the Pleiades will be 6 degrees to the right. By about 2 a.m. the Pleiades will be 8 degrees to the lower right of the Moon, and it will continue to separate as the morning progresses.
As mentioned last month, one of the three major meteor showers of the year, the Geminids (004 GEM), will peak Saturday morning, December 14. The light of the nearly full Moon will interfere. In a good year, this shower can produce 150 visible meteors per hour under ideal conditions, but this will not be a good year. For the Washington, D.C. area the MeteorActive app predicts that at about 2 a.m. EST, under bright suburban sky conditions, the peak rate from the Geminids and all other background sources might reach 20 meteors per hour. See the meteor summary above for suggestions for meteor viewing.
Saturday morning, December 14 The full Moon, the bright planet Jupiter, and the bright star Aldebaran will form a triangle. As Aldebaran sets on the west-northwestern horizon at 6:10 a.m. EST it will be 9 degrees to the lower left of the Moon with Jupiter 7 degrees to the upper left. Morning twilight will begin 6 minutes later.
Saturday evening, December 14 The full Moon will have shifted to the other side of Jupiter. Jupiter will be 6 degrees to the right of the Moon as evening twilight ends at 5:50 p.m EST and the pair will separate as the night progresses.
Sunday morning, December 15, the next full Moon will be at 4:02 a.m. EST This will be Saturday evening from Alaska Time westwards to the International Date Line. The Moon will appear full for about three days around this time, from Friday evening through Monday morning, making this a full Moon weekend.
Monday evening into Tuesday morning, December 16 to 17 The bright star Pollux will appear near the waning gibbous Moon. As Pollux rises above the northeastern horizon at 6:25 p.m. EST, it will be 7 degrees to the lower left of the Moon. By the time the Moon reaches its highest for the night at 1:55 a.m. Pollux will be 4 degrees to the upper left. As morning twilight begins at 6:18 a.m., Pollux will be 3 degrees to the upper right.
Tuesday night into Wednesday morning, December 17 to 18 The bright planet Mars, about a month away from its brightest for the year, will appear near the waning gibbous Moon. As Mars rises on the east-northeastern horizon at 7:34 p.m. EST it will be 4 degrees to the lower left of the Moon. By the time the Moon reaches its highest for the night at 2:50 a.m., Mars will be 1 degree to the lower left. When Mars is closest to the Moon a little before 5:00 a.m., it will be a quarter of a degree from the center of the Moon or an eighth of a degree from the edge of the Moon. As morning twilight begins at 6:18 a.m., Mars will be a degree to the lower right of the Moon. The far north of North America and Asia will see the Moon pass in front of Mars. Note that for some areas this occultation will occur during the daytime.
Thursday night into Friday morning, December 19 to 20 The bright star Regulus will appear near the waning gibbous Moon. As Regulus rises on the east-northeastern horizon at 9:39 p.m. EST it will be 3 degrees to the lower right of the Moon. As the Moon reaches its highest for the night at 4:26 a.m., Regulus will be 2 degrees to the lower right. Regulus will be 2.5 degrees to the lower right as morning twilight begins at 6:19 a.m.
Thursday morning, December 20 This will be the last morning the bright planet Jupiter will be above the west-northwestern horizon as morning twilight begins.
Saturday morning, December 21 at 4:20 a.m. EST This is the winter solstice for the Northern Hemisphere, the astronomical end of fall and start of winter. Europeans have used two main ways to divide the year into seasons and define winter. The old Celtic calendar used in much of pre-Christian Europe considered winter to be the quarter of the year with the shortest periods of daylight and the longest periods of night, so that winter started around Halloween and ended around Groundhog Day, hence the origin of these traditions. However, since it takes time for our planet to cool off, the quarter year with the coldest average temperatures starts later than the quarter year with the shortest days. In our modern calendar we approximate this by having winter start on the winter solstice and end on the spring equinox. The last time I checked NOAA data sources, for the Washington, D.C. area at least, the quarter year with the coldest average temperatures started the first week of December and ended the first week of March.
Worldwide, many festivals are associated with the winter solstice, including Yule and the Chinese Dongzhi Festival.
The solar day from solar noon on Saturday, December 21 to solar noon on Sunday, December 22 will be the longest solar day of the year, 29.8 seconds longer than 24 hours.
Sunday morning, December 22 For the Washington, D.C. area, under bright suburban conditions, the MeteorActive app predicts that at about 5:30 a.m. EST the peak rate from the Ursids and all other background sources might reach 5 meteors per hour (with most of these background meteors).
Sunday evening, December 22 The waning Moon will appear half-full as it reaches its last quarter at 5:18 p.m. EST.
Monday morning, December 23 This will be when the planet Mercury will appear at its highest above the east-southeastern horizon (7 degrees) as morning twilight begins at 6:21 a.m. EST. The bright star about 7 degrees to the lower right of Mercury will be Antares.
Early Tuesday morning, December 24, at 2:27 a.m. EST The Moon will be at apogee, its farthest from Earth for this orbit.
Also on Tuesday morning, December 24 The bright star Spica will appear near the waning crescent Moon. As Spica rises on the east-southeastern horizon at 1:55 a.m. EST, it will be 6 degrees below the Moon. As morning twilight begins 3.5 hours later at 6:21 a.m., Spica will be 4 degrees to the lower left. For parts of Asia and the Pacific Ocean the Moon will pass in front of Spica.
Tuesday night, December 24 This will be when the planet Mercury reaches its greatest angular separation from the Sun as seen from Earth for this apparition (called greatest elongation). Because the angle between the line from the Sun to Mercury and the line of the horizon changes with the seasons, the date when Mercury and the Sun appear farthest apart as seen from Earth is not always the same as when Mercury appears highest above the east-southeastern horizon as morning twilight begins, which will occur on December 23.
Wednesday morning, December 25 The Moon will have shifted to the other side of Spica. As the Moon rises on the east-southeastern horizon at 2:23 a.m. EST, Spica will be 7 degrees to the upper right of the Moon, and the pair will separate as the morning progresses.
Saturday morning, December 28 The bright star Antares will be 1.5 degrees to the lower left of the waning crescent Moon, with Mercury about 10 degrees to the left of the Moon. The Moon will rise first above the southeastern horizon at 5:32 a.m. EST, followed by Antares 8 minutes later and Mercury 5 minutes after that at 5:45 a.m. As morning twilight begins less than an hour later at 6:23 a.m., the Moon will be 7 degrees above the southeastern horizon. For an area in the mid-Pacific the Moon will block Antares while the sky is dark. Note that for most of the area in the Atlantic, South America, and the Pacific, this occultation will occur in the daytime and only be visible with binoculars or a telescope.
Monday afternoon, December 30, at 5:27 p.m. EST This will be the new Moon, when the Moon passes between Earth and the Sun, and it will not be visible from PEarth. The day of, or the day after, the New Moon marks the start of the new month for most lunisolar calendars. The 12th month of the Chinese calendar starts on December 31. Sundown on Tuesday, December 31, will mark the start of Tevet and the start of the seventh day of Hanukkah in the Hebrew calendar.
In the Islamic calendar, the months traditionally start with the first sighting of the waxing crescent Moon. Many Muslim communities now follow the Umm al-Qura Calendar of Saudi Arabia, which uses astronomical calculations to start months in a more predictable way. Using this calendar, sundown on Tuesday, December 31, will probably mark the beginning of Rajab, the seventh month of the Islamic calendar. Rajab is one of the four sacred months in which warfare and fighting are forbidden.
Friday morning, Jan. 3, 2025 At about 6 a.m. EST for the Washington, D.C. area, under bright suburban sky conditions, the MeteorActive app predicts the peak rate from the Quadrantids and all other background sources might reach 14 meteors per hour. Going to a nearby dark sky area (like Sky Meadows State Park in Virginia) might get these rates up to about 34 meteors per hour.
Friday evening, January 3 The bright planet Venus will appear near the waxing crescent Moon. As evening twilight ends at 6:02 p.m. EST the Moon will be 29 degrees above the southwestern horizon with Venus 3.5 degrees to the lower right. As Venus sets on the west southwestern horizon less than 3 hours later at 8:49 p.m., it will be 4.5 degrees to the lower right of the Moon.
Saturday morning, January 4 Earth will be at perihelion, the closest we get to the Sun in our orbit. Between perihelion and 6 months later at aphelion there is about a 6.7% difference in the intensity of the sunlight reaching Earth, one of the reasons the seasons in the Southern hemisphere are more extreme than in the Northern Hemisphere. Perihelion is also when Earth is moving the fastest in its orbit around the Sun, so if you run east at local midnight, you will be moving about as fast as you can for your location (in Sun-centered coordinates).
Saturday morning, January 4 Ignoring Daylight Saving Time, for the Washington, D.C. area and similar latitudes (I’ve not checked elsewhere), this will be the morning with the latest sunrise of the year at 7:26:56 a.m. EST.
Saturday evening, January 4 This will be the first evening the planet Mars will be above the east-northeastern horizon as evening twilight ends, joining Venus, Jupiter, and Saturn in the sky. Mars is approaching its closest and brightest for the year, which will happen on January 15.
Also on Saturday evening, January 4 The planet Saturn will appear near the waxing crescent Moon. As evening twilight ends at 6:03 p.m. EST, the Moon will be 40 degrees above the south-southwestern horizon with Saturn 3 degrees to the lower right. As Saturn sets on the western horizon less than 4 hours later at 9:53 p.m., it will be 5 degrees below the Moon.
Monday evening, January 6 The Moon will appear half full as it reaches its first quarter at 6:56 p.m. EST (when it will be 56 degrees above the south-southwestern horizon).
Tuesday evening, January 7 At 7:07 p.m. EST, the Moon will be at perigee, its closest to Earth for this orbit.
Thursday evening, January 9 The waxing gibbous Moon will pass in front of the Pleiades star cluster. This may be viewed best with binoculars, as the brightness of the Moon will make it hard to see the stars in this star cluster. As evening twilight ends at 6:07 p.m. EST, the Pleiades will appear 1 degree to the lower left of the full Moon. Over the next few hours, including as the Moon reaches its highest for the night at 8:37 p.m., the Moon will pass in front of the Pleiades, blocking many of these stars from view. By about midnight the Pleiades will appear about 1 degree below the Moon, and the Moon and the Pleiades will separate as Friday morning progresses.
Also on Thursday night, January 9 This will be when the planet Venus reaches its greatest angular separation from the Sun as seen from Earth for this apparition (called greatest elongation). Because the angle between the line from the Sun to Venus and the line of the horizon changes with the seasons, the date when Venus and the Sun appear farthest apart as seen from Earth is not always the same as when it appears highest above the west-southwestern horizon as evening twilight ends, which occurs on January 27.
Friday evening, January 10 Jupiter will appear near the waxing gibbous Moon. As evening twilight ends at 6:08 p.m. EST, Jupiter will be 5 degrees to the lower right. As the Moon reaches its highest for the night at 9:37 p.m., Jupiter will be 6 degrees below the Moon. The pair will continue to separate until Jupiter sets Saturday morning at 4:45 a.m.
Sunday evening, January 12 There is a very slight chance that the sungrazing comet, C/2024 G3 (ATLAS) (discovered in April 2024) will be visible 5 degrees to the upper right of the setting Sun. Most likely, this comet will not be bright enough to see in the daytime or will break up and vanish from view like comet C/2024 S1 (ATLAS) did in October. The odds are low, but if the horizon is very clear, your best chance of seeing this comet might be after sunset at 5:07 p.m. EST, but before the comet sets about 10 minutes later.
The full Moon after next will be Monday evening, January 13, at 5:27 p.m. EST. This will be on Tuesday from the South Africa Time and Eastern European Time zones eastward across the rest of Africa, Europe, Asia, Australia, etc., to the International Date Line in the mid-Pacific. The Moon will appear full for about three days around this time, from Sunday evening (and possibly the last part of Sunday morning) into Wednesday morning. On Monday night the full Moon will appear near and pass in front of the bright planet Mars, with the bright star Pollux above the pair. As evening twilight ends at 6:11 p.m. EST, the three will form a triangle, with Mars 2 degrees to the lower left and Pollux 3 degrees to the upper left of the Moon. For most of the continental USA as well as parts of Africa, Canada, and Mexico, the Moon will pass in front of Mars. Times will vary for other locations, but for NASA Headquarters in Washington, D.C., Mars will vanish behind the bottom of the Moon at about 9:16 p.m. and reappear from behind the upper right of the Moon at about 10:31 p.m. By the time the Moon reaches its highest for the night early on Tuesday morning at 12:37 a.m., Mars will be 1 degree to the right of the Moon and Pollux 5 degrees to the upper right. As morning twilight begins at 6:23 a.m., Mars will be 4 degrees and Pollux 8 degrees to the lower right of the Moon.
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By European Space Agency
Zoom into Solar Orbiter's four new Sun images, assembled from high-resolution observations by the spacecraft's PHI and EUI instruments made on 22 March 2023. The PHI images are the highest-resolution full views of the Sun's visible surface to date, including maps of the Sun's messy magnetic field and movement on the surface. These can be compared to the new EUI image, which reveals the Sun's glowing outer atmosphere, or corona.
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