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By NASA
The study of X-ray emission from astronomical objects reveals secrets about the Universe at the largest and smallest spatial scales. Celestial X-rays are produced by black holes consuming nearby stars, emitted by the million-degree gas that traces the structure between galaxies, and can be used to predict whether stars may be able to host planets hospitable to life. X-ray observations have shown that most of the visible matter in the universe exists as hot gas between galaxies and have conclusively demonstrated that the presence of “dark matter” is needed to explain galaxy cluster dynamics, that dark matter dominates the mass of galaxy clusters, and that it governs the expansion of the cosmos.
X-ray observations also enable us to probe mysteries of the Universe on the smallest scales. X-ray observations of compact objects such as white dwarfs, neutron stars, and black holes allow us to use the Universe as a physics laboratory to study conditions that are orders of magnitude more extreme in terms of density, pressure, temperature, and magnetic field strength than anything that can be produced on Earth. In this astrophysical laboratory, researchers expect to reveal new physics at the subatomic scale by conducting investigations such as probing the neutron star equation of state and testing quantum electrodynamics with observations of neutron star atmospheres. At NASA’s Marshall Space Flight Center, a team of scientists and engineers is building, testing, and flying innovative optics that bring the Universe’s X-ray mysteries into sharper focus.
A composite X-ray/Optical/Infrared image of the Crab Pulsar. The X-ray image from the Chandra X-ray Observatory (blue and white), reveals exquisite details in the central ring structures and gas flowing out of the polar jets. Optical light from the Hubble Space Telescope (purple) shows foreground and background stars as pinpoints of light. Infrared light from the Spitzer Space Telescope (pink) traces cooler gas in the nebula. Finally, magnetic field direction derived from X-ray polarization observed by the Imaging X-ray Polarimetry Explorer is shown as orange lines. Magnetic field lines: NASA/Bucciantini et al; X-ray: NASA/CXC/SAO; Optical: NASA/STScI; Infrared: NASA-JPL-Caltech Unlike optical telescopes that create images by reflecting or refracting light at near-90-degree angles (normal incidence), focusing X-ray optics must be designed to reflect light at very small angles (grazing incidence). At normal incidence, X-rays are either absorbed by the surface of a mirror or penetrate it entirely. However, at grazing angles of incidence, X-rays reflect very efficiently due to an effect called total external reflection. In grazing incidence, X-rays reflect off the surface of a mirror like rocks skipping on the surface of a pond.
A classic design for astronomical grazing incidence optics is the Wolter-I prescription, which consists of two reflecting surfaces, a parabola and hyperbola (see figure below). This optical prescription is revolved around the optical axis to produce a full-shell mirror (i.e., the mirror spans the full circumference) that resembles a gently tapered cone. To increase the light collecting area, multiple mirror shells with incrementally larger diameters and a common focus are fabricated and nested concentrically to comprise a mirror module assembly (MMA).
Focusing optics are critical to studying the X-ray universe because, in contrast to other optical systems like collimators or coded masks, they produce high signal-to-noise images with low background noise. Two key metrics that characterize the performance of X-ray optics are angular resolution, which is the ability of an optical system to discriminate between closely spaced objects, and effective area, which is the light collecting area of the telescope, typically quoted in units of cm2. Angular resolution is typically measured as the half-power diameter (HPD) of a focused spot in units of arcseconds. The HPD encircles half of the incident photons in a focused spot and measures the sharpness of the final image; a smaller number is better.
Schematic of a full-shell Wolter-I X-ray optic mirror module assembly with five concentrically nested mirror shells. Parallel rays of light enter from the left, reflect twice off the reflective inside surface of the shell (first off the parabolic segment and then off the hyperbolic segment), and converge at the focal plane. NASA MSFC NASA Marshall Space Flight Center (MSFC) has been building and flying lightweight, full-shell, focusing X-ray optics for over three decades, always meeting or exceeding angular resolution and effective area requirements. MSFC utilizes an electroformed nickel replication (ENR) technique to make these thin full-shell X-ray optics from nickel alloy.
X-ray optics development at MSFC began in the early 1990s with the fabrication of optics to support NASA’s Advanced X-ray Astrophysics Facility (AXAF-S) and then continued via the Constellation-X technology development programs. In 2001, MSFC launched a balloon payload that included two modules each with three mirrors, which produced the first focused hard X-ray (>10 keV) images of an astrophysical source by imaging Cygnus X-1, GRS 1915, and the Crab Nebula. This initial effort resulted in several follow-up missions over the next 12 years, and became known as the High Energy Replicated Optics (HERO) balloon program.
In 2012, the first of four sounding rocket flights of the Focusing Optics X-ray Solar Imager (FOXSI) flew with MSFC optics onboard, producing the first focused images of the Sun at energies greater than 5 keV. In 2019 the Astronomical Roentgen Telescope X-ray Concentrator (ART-XC) instrument on the Spectr-Roentgen-Gamma Mission launched with seven MSFC-fabricated X-ray MMAs, each containing 28 mirror shells. ART-XC is currently mapping the sky in the 4-30 keV hard X-ray energy range, studying exotic objects like neutron stars in our own galaxy as well as active galactic nuclei, which are spread across the visible universe. In 2021, the Imaging X-ray Polarimetry Explorer (IXPE), flew and is now performing extraordinary science with an MSFC-led team using three, 24-shell MMAs that were fabricated and calibrated in-house.
Most recently, in 2024, the fourth FOXSI sounding rocket campaign launched with a high-resolution MSFC MMA. The optics achieved 9.5 arcsecond HPD angular resolution during pre-flight test with an expected 7 arcsecond HPD in gravity-free flight, making this the highest angular resolution flight observation made with a nickel-replicated X-ray optic. Currently MSFC is fabricating an MMA for the Rocket Experiment Demonstration of a Soft X-ray (REDSoX) polarimeter, a sounding rocket mission that will fly a novel soft X-ray polarimeter instrument to observe active galactic nuclei. The REDSoX MMA optic will be 444 mm in diameter, which will make it the largest MMA ever produced by MSFC and the second largest replicated nickel X-ray optic in the world.
Scientists Wayne Baumgartner (left, crouched) and Nick Thomas (left, standing) calibrate an IXPE MMA in the MSFC 100 m Beamline. Scientist Stephen Bongiorno (right) applies epoxy to an IXPE shell during MMA assembly. NASA MSFC The ultimate performance of an X-ray optic is determined by errors in the shape, position, and roughness of the optical surface. To push the performance of X-ray optics toward even higher angular resolution and achieve more ambitious science goals, MSFC is currently engaged in a fundamental research and development effort to improve all aspects of full-shell optics fabrication.
Given that these optics are made with the Electroformed Nickel Replication technique, the fabrication process begins with creation of a replication master, called the mandrel, which is a negative of the desired optical surface. First, the mandrel is figured and polished to specification, then a thin layer of nickel alloy is electroformed onto the mandrel surface. Next, the nickel alloy layer is removed to produce a replicated optical shell, and finally the thin shell is attached to a stiff holding structure for use.
Each step in this process imparts some degree of error into the final replicated shell. Research and development efforts at MSFC are currently concentrating on reducing distortion induced during the electroforming metal deposition and release steps. Electroforming-induced distortion is caused by material stress built into the electroformed material as it deposits onto the mandrel. Decreasing release-induced distortion is a matter of reducing adhesion strength between the shell and mandrel, increasing strength of the shell material to prevent yielding, and reducing point defects in the release layer.
Additionally, verifying the performance of these advanced optics requires world-class test facilities. The basic premise of testing an optic designed for X-ray astrophysics is to place a small, bright X-ray source far away from the optic. If the angular size of the source, as viewed from the optic, is smaller than the angular resolution of the optic, the source is effectively simulating X-ray starlight. Due to the absorption of X-rays by air, the entire test facility light path must be placed inside a vacuum chamber.
At MSFC, a group of scientists and engineers operate the Marshall 100-meter X-ray beamline, a world-class end-to-end test facility for flight and laboratory X-ray optics, instruments, and telescopes. As per the name, it consists of a 100-meter-long vacuum tube with an 8-meter-long, 3-meter-diameter instrument chamber and a variety of X-ray sources ranging from 0.25 – 114 keV. Across the street sits the X-Ray and Cryogenic Facility (XRCF), a 527-meter-long beamline with an 18-meter-long, 6-meter-diameter instrument chamber. These facilities are available for the scientific community to use and highlight the comprehensive optics development and test capability that Marshall is known for.
Within the X-ray astrophysics community there exist a variety of angular resolution and effective area needs for focusing optics. Given its storied history in X-ray optics, MSFC is uniquely poised to fulfill requirements for large or small, medium- or high-angular-resolution X-ray optics. To help guide technology development, the astrophysics community convenes once per decade to produce a decadal survey. The need for high-angular-resolution and high-throughput X-ray optics is strongly endorsed by the National Academies of Sciences, Engineering, and Medicine report, Pathways to Discovery in Astronomy and Astrophysics for the 2020s.In pursuit of this goal, MSFC is continuing to advance the state of the art in full-shell optics. This work will enable the extraordinary mysteries of the X-ray universe to be revealed.
Project Leads
Dr. Jessica Gaskin and Dr. Stephen Bongiorno, NASA Marshall Space Flight Center (MSFC)
Sponsoring Organizations
The NASA Astrophysics Division supports this work primarily through the Internal Scientist Funding Model Direct Work Package and competed solicitations. This work is also supported by the Heliophysics Division through competed solicitations, as well as by directed work from other government entities.
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Last Updated Oct 15, 2024 Related Terms
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By NASA
29 Min Read The Next Full Moon is a Supermoon, and the Hunter’s Moon
A supermoon rises behind the U.S. Capitol, on March 9, 2020, in Washington. Credits:
NASA/Joel Kowsky The Next Full Moon is a Supermoon; the Hunter’s Moon; the Travel Moon, the Dying Grass Moon, or the Sanguine or Blood Moon; the start of Sukkoth; Sharad Purnima, Kumara Purnima, Kojagari Purnima, Navanna Purnima Kojagrat Purnima, or Kaumudi Purnima; the end of Vassa and Pavarana; the Thadingyut Festival Moon; the end of the Phaung Daw U Pagoda Festival; and Vap Poya.
The next full Moon will be Thursday morning, Oct. 17, 2024, at 7:26 a.m. EDT. This will be late Wednesday night for the International Date Line West time zone and early Friday morning from New Zealand Time eastwards to the International Date Line. The Moon will appear full for about three days around this time, from Tuesday evening through Friday morning.
This will be the third of four consecutive supermoons (and the brightest by a tiny margin).
As the full Moon after the Harvest Moon, this will be the Hunter’s Moon. The earliest written use of the term “Hunter’s Moon” identified in the Oxford English Dictionary is from 1710. According to the Farmer’s Almanac, with the leaves falling and the deer fattened, it is time to hunt. Since the harvesters have reaped the fields, hunters can easily see the animals that have come out to glean (and the foxes that have come out to prey upon them).
The Maine Farmer’s Almanac first published Native American names for the full Moons in the 1930s. Over time these names have become widely known and used.
According to this almanac, as the full Moon in October the Algonquin tribes in what is now the northeastern United States called this the Travel Moon, the Dying Grass Moon, or the Sanguine or Blood Moon. Some sources indicate that the Dying Grass, Sanguine, and Blood Moon names are related to the turning of the leaves and dying back of plants with the start of fall. Others indicate that the names Sanguine and Blood Moon are associated with hunting to prepare for winter. I have read that the name “Travel Moon” comes from observing the migration of birds and other animals preparing for the winter. I don’t know, but this name may also refer to the season when the more northern tribes would move down from the mountains for the winter. For example, both the Iroquois and Algonquin would hunt in the Adirondack Mountains during the summertime but leave in fall to avoid the harsh mountain winters.
As the full Moon in the Hebrew month of Tishrei, this full Moon falls near the start of Sukkoth, a 7-day holiday starting on the 15th day of the month. Sukkoth is also known as the Feast of Tabernacles or the Feast of the Ingathering. Sukkoth honors both the sheltering of the People of Israel during the 40 years in the wilderness in the Book of Leviticus as well as an ancient harvest festival in the Book of Exodus. Sukkot is named for the sukkah (booths or huts) traditionally built for the occasion that represent the temporary huts in which Israelites lived after escaping from Egypt. Families symbolically invite ancestors to share meals in the sukkah and spend as much time as possible there throughout the week. This year Sukkoth starts at sunset on October 16 and ends at sunset on October 23. See https://en.wikipedia.org/wiki/Sukkot for more information.
For Hindus, this is Sharad Purnima, also known as Kumara Purnima, Kojagari Purnima, Navanna Purnima Kojagrat Purnima, or Kaumudi Purnima. This is a harvest festival celebrated in a variety of ways. See https://en.wikipedia.org/wiki/Sharad_Purnima for more information.
For Buddhists, this Moon marks the end of Vassa, the three-month period of fasting for monks tied to the monsoons (Vassa is sometimes given the English names “Rains Retreat” or “Buddhist Lent”). There are numerous festivals and holy days associated with this Moon at the end of Vassa. Many Buddhists observe the holy day Pavarana on this day.
In Myanmar, this full Moon corresponds with the three-day Thadingyut Festival of Lights, also known as the Lighting Festival of Myanmar.
Also in Myanmar, this full Moon is near the end of the Phaung Daw U Pagoda Festival. This festival began on the first Waxing Moon day of the month of Thadingyut and will end a few days past this full Moon.
In Sri Lanka, this is Vap Poya, which is followed (usually within the lunar month) by the Kathina festival, during which people give gifts to the monks, particularly new robes (so this lunar month is sometimes called the Month of Robes).
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 ninth month of the Chinese year of the Dragon and Rabi’ al-Thani, also called Rabiʽ al-Akhir, the fourth month of the Islamic year.
As usual, the wearing of suitably celebratory celestial attire is encouraged in honor of the full Moon. Enjoy this harvest season, remember your ancestors, and consider camping out with your family. Here’s wishing you safe travels!
Summary of Key Celestial Events
Here are more 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.):
As Autumn continues the daily periods of sunlight continue shortening. On Thursday, Oct. 17, (the day of the full Moon), morning twilight will begin at 6:22 a.m. EDT, sunrise will be at 7:20 a.m., solar noon will be at 12:53 p.m. when the Sun will reach its maximum altitude of 41.5 degrees, sunset will be at 6:26 p.m., and evening twilight will end at 7:24 p.m.. By Friday, Nov. 15, (the day of the full Moon after next), we will have switched from Daylight Saving to Standard Time. Morning twilight will begin at 5:51 a.m. EST, sunrise will be at 6:51 AM, solar noon will be at 11:53 a.m. when the Sun will reach its maximum altitude of 32.4 degrees, sunset will be at 4:54 p.m., and evening twilight will end at 5:55 p.m.
This should be a good season for Saturn viewing, especially through a backyard telescope. Saturn was at its closest and brightest the night of September 7. It will be shifting west each evening, making it higher in the sky and friendlier for evening viewing (particularly for children with earlier bedtimes). Through a telescope you should be able to see Saturn’s bright moon Titan and its rings. The rings are appearing thinner and will be edge-on to the Earth by early 2025. We won’t get the “classic” view of Saturn with its rings again until 2026.
Comets
Two comets might be visible during this lunar cycle. For both of these comets I recommend paying attention to the news and checking out local astronomy websites, as we should have better forecasts of how these comets are behaving as we get closer to the opportunities for prime viewing. Particularly for the newly discovered Comet C/2024 S1 (ATLAS), others (with newer information and better modeling tools) should be able to provide better guidance on when and where to look.
Comet C/2023 A3 (Tsuchinshan-ATLAS) has already survived its close pass by the Sun and will be its closest to the Earth on October 12 (five days before the full Moon). After its closest approach it will be in the evening sky as twilight ends. If it continues on its current brightness curve it should be visible with binoculars and (under good conditions) with the unaided eye for at least a few evenings after the 12th, dimming as it moves away from the Sun and the Earth. On October 12, as evening twilight ends (at 7:31 p.m. EDT) the comet will be 4 degrees above the western horizon to the right of Venus (at an estimated visual magnitude of 2.9). As twilight ends on October 13 it will be 10 degrees above the western horizon (magnitude 3), 12 degrees on October 14 (magnitude 3.2), 16 degrees on October 15 (magnitude 3.3), etc. Current brightness curves predict it will dim to magnitude 6.2 by the end of October (nearing the edge of visibility with the unaided eye under dark and clear conditions).
Comet C/2024 S1 (ATLAS) was discovered recently. It’s gotten a lot of attention because if it doesn’t break up as it approaches the Sun, it may become bright enough to see during the daytime. However, I want to avoid raising unrealistic expectations. From the information I’ve been able to find so far, I expect that at night this comet will only be visible with binoculars or a telescope, as its path will not bring it very close to the Earth. For the Washington, D.C. area (and similar latitudes) this comet will be above the horizon before morning twilight begins from now to October 21 as the comet falls towards the Sun. If it doesn’t break into pieces too small to see around closest approach, it should also be visible (with binoculars or a telescope) from November 2 to December 19 as the comet speeds away from the Sun.
However, it is a sungrazing comet and will be passing just a few solar radii from the surface of the Sun. This is so close that the sunlight will be more than 14,000 times brighter than at Earth. Sunlight this intense may cause it to break up and evaporate. But if it remains intact, based on the estimates I have while writing this, the comet will be bright enough to see during the daylight for about an hour or two around closest approach.
One brightness model estimates this comet will be brighter than magnitude -5 from 7:12 a.m. to 8:06 a.m. EDT. Based on this timing, Africa, Europe, and South America are best situated to see this daylight comet. From the East Coast of North America the comet at its brightest will be to the lower left of the Sun just after sunrise, which means we will be viewing it through more air, increasing the chance of interference from scattered sunlight and clouds.
To look for this comet during the short period when it is very close to the Sun, find out for your location which side of the Sun the comet will be on, then find something to block the Sun (e.g., a house or building, etc., the farther away the better) so you can look for the comet without staring at the Sun. Be careful and plan ahead, as it may be difficult to find a location that has both a clear view to the right part of the east-southeastern horizon and a large overhanging object to block the Sun while allowing you to see to the lower left of the Sun. I strongly recommend AGAINST using binoculars or a telescope because accidentally using high powered lenses to focus intense sunlight into your eyes is a blindingly bad idea.
If you are interested, here is some more background on Comet C/2024 S1 (ATLAS). Otherwise, skip this paragraph. This comet was discovered on Sept. 27, 2024, by one of the Asteroid Terrestrial-impact Last Alert System (ATLAS) telescopes in Hawaii. This comet’s orbit suggests it is part of a family of comets called Kreutz sungrazers that pass very close to the Sun. These comets are thought to be fragments of a large sungrazing comet, the Great Comet of 1106, that broke up as it swung around the Sun 918 years ago. This 1106 comet might itself be a fragment of an even larger sungrazing comet, possibly the Great Comet of 371 BC (also known as Aristotle’s Comet). This comet was so bright it cast shadows at night like the full Moon. Several other members of this comet family have been great comets, including the Great Comet of 1843 and the Great Comet of 1882. The most recent great comet from this family was Comet Ikeya–Seki in 1965. Since its launch in 1995, the Solar and Heliospheric Observatory (SOHO) satellite has observed more than 4000 smaller Kreutz sungrazers, some only a few meters across, with none of these smaller comets surviving their close pass by the Sun.
Meteor Showers
Five meteor showers are predicted to peak during this lunar cycle. Three meteor showers peak between October 18 and 24 when the light of the waning Moon will interfere, the most significant being the Orionids peaking on October 21. While the Orionids tend to be brighter than average and to peak at about 20 meteors per hour (under ideal conditions), the light of the waning gibbous Moon will make these harder to see this year, especially from our light-polluted urban areas. Two minor meteor showers will peak in early November. These showers are the Southern Taurids (peaking at 7 meteors per hour on November 5) and the Northern Taurids (peaking at 5 meteors per hour on November 12). These showers overlap to produce their highest combined rate around November 5, but this rate is low enough that seeing these meteors from urban locations will be difficult.
Evening Sky Highlights
On the evening of Thursday, Oct. 17, 2024 (the evening of the full Moon), as twilight ends (at 7:24 p.m. EDT), the rising Moon will be 9 degrees above the eastern horizon. Saturn will be 27 degrees above the southeastern horizon. Bright Venus will be 6 degrees above the west-southwestern horizon. Comet C/2023 A3 (Tsuchinshan-ATLAS) will be to the upper right of Venus at 22 degrees above the western horizon (at a visual magnitude of 3.7 if it continues to follow its current brightness curve). The bright star closest to overhead will be Deneb at 80 degrees above the northeastern 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. Deneb 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 the Earth. Deneb is about 2,600 light years from us.
As this lunar cycle progresses, Saturn and the background of stars will appear to shift westward each evening (as the Earth moves around the Sun). Bright Venus will shift to the left along the southwestern horizon in the opposite direction as the stars, passing above the bright star Antares (they will appear 3 degrees apart at their closest on October 25). October 21 will be the first evening the planet Mercury will be above the west-southwestern horizon 30 minutes after sunset (an estimate of when it will first be visible in the glow of dusk). The waxing Moon will pass by Antares on November 3, Venus on November 4, and Saturn on November 10. November 11 will be when Mercury will first appear above the horizon as twilight ends.
By the evening of Friday, November 15 (the evening of the full Moon after next), as twilight ends at 5:55 p.m. EST, the rising Moon will be 14 degrees above the east-northeastern horizon with the Pleiades star cluster 5 degrees to the lower left. The brightest planet in the sky will be Venus at 12 degrees above the southwestern horizon. Next in brightness will be Mercury at less than a degree above the west-southwestern horizon. Saturn will be 38 degrees above the south-southeastern horizon. Comet C/2023 A3 (Tsuchinshan-ATLAS) will be 39 degrees above the west-southwestern horizon, with its current brightness curve predicting it will have faded to magnitude 8, too faint to see with the unaided eye. The bright star closest to overhead will still be Deneb at 79 degrees above the northwestern horizon.
Morning Sky Highlights
On the morning of Thursday, October 17, 2024 (the morning of the full Moon), as twilight begins at 6:22 a.m. EDT, the setting Moon will be 11 degrees above the western horizon. The brightest planet in the sky will be Jupiter at 63 degrees above the west-southwestern horizon. Mars will be at 72 degrees above the south-southeastern horizon. Comet C/2024 S1 (ATLAS) will be 6 degrees above the east-southeastern horizon but will likely be too dim to be seen without a telescope (current projection, magnitude 12.7). The bright star appearing closest to overhead will be Pollux, the 17th brightest star in our night sky and the brighter of the twin stars in the constellation Gemini, at 75 degrees above the southeastern horizon. Pollux is an orange tinted star about 34 lightyears from Earth. It is not quite twice the mass of our Sun but about 9 times the diameter and 33 times the brightness.
As this lunar cycle progresses, Jupiter, Mars, and the background of stars will appear to shift westward each evening. Comet C/2024 S1 (ATLAS), visible with binoculars or a telescope, will brighten but shift lower as it races towards the Sun, with October 21 the last morning it will be above the horizon as morning twilight begins (estimated magnitude of 11.2). The waning Moon will pass by the Pleiades star cluster on October 19, Jupiter on October 21, Mars and Pollux on October 23, Regulus on October 26, and Spica on October 31. Comet C/2024 S1 (ATLAS) will pass its closest to the Sun on the morning of October 28 (when, if the sky is very clear, it might be bright enough to see in the daylight for an hour or so around 7:39 a.m.). If this comet survives its close pass by the Sun, it may reemerge in the morning sky. November 2 will be the first morning it will be above the horizon as morning twilight begins (with an estimated magnitude of 10.5, visible with binoculars or a telescope).
By the morning of Friday, November 15 (the morning of the full Moon after next), as twilight begins (at 5:51 a.m. EST), the setting full Moon will be 7 degrees above the west-northwestern horizon. The brightest planet in the sky will be Jupiter at 35 degrees above the western horizon. Mars will be at 68 degrees above the southwestern horizon. Comet C/2024 S1 (ATLAS) will be 13 degrees above the southeastern horizon (estimated magnitude 14.2). The bright star appearing closest to overhead will still be Pollux at 69 degrees above the west-southwestern horizon (higher than Mars by about a half degree).
Detailed Daily Guide
.Here for your reference is a day-by-day listing of celestial events between now and the full Moon on October 17, 2024. 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 or a star-watching guide from a local observatory, news outlet, or astronomy club.
Saturday morning, October 12: At 11:10 a.m. EDT, Comet C/2023 A3 (Tsuchinshan-ATLAS) will be at its closest to Earth. Although it will be on the horizon as evening twilight ends the evening before (Friday), it may be hard to see. Our first chance to see it above the horizon as evening twilight ends (at 7:31 PM) will likely be Saturday evening, when the comet will be 4 degrees above the western horizon, similar in altitude and to the right of Venus.
As of September 28 this comet is still following a brightness curve that predicts it to be quite bright near closest approach and remain visible to unaided human eyes (under clear dark sky conditions) through the end of October. How bright the comet will be and how quickly it actually dims will depend upon the gas and dust it is giving off, which can vary quickly and unpredictably, but it should be an impressive show in the evenings after October 12.
The comet will likely dim as it moves away from the Earth, but also appear higher in the sky and set later each evening, giving us more time and darker skies to look for it. As evening twilight ends on October 13 it will be 10 degrees above the western horizon, 12 degrees on October 14, 16 degrees on October 15, etc. Current brightness curves predict it will still be around magnitude 6 by the end of October (still visible to the unaided eye under good conditions).
Monday evening, October 14: The planet Saturn will appear near the waxing gibbous Moon. As evening twilight ends (at 7:28 p.m. EDT) Saturn will be 4 degrees to the upper right. The Moon will reach its highest for the night about 3.5 hours later (at 10:53 p.m.) with Saturn 5 degrees to the lower right. The pair will continue to separate, with Saturn setting first 5 hours after that (at 4:09 a.m.). For parts of Southern Asia and Africa the Moon will block Saturn from view.
Wednesday evening, October 16: At 8:57 p.m. EDT (CSG 8:47), the Moon will be at perigee, its closest to the Earth for this orbit.
As mentioned above, the full Moon will be Thursday morning, Oct. 17, at 7:26 a.m. EDT. This will be late Wednesday night for the International Date Line West time zone and early Friday morning from New Zealand Time eastwards to the International Date Line. This will be the third of four consecutive supermoons (and the brightest by a tiny margin). The Moon will appear full for about 3 days around this time, from Tuesday evening through Friday morning.
Saturday night into Sunday morning, October 19 to 20: The Pleiades star cluster will appear near the waning gibbous Moon. At moonrise (7:42 p.m. EDT) on the east-northeastern horizon the Pleiades will be 3 degrees to the upper right. By the time the Moon reaches its highest for the night at 3:28 a.m., the Pleiades will be 7 degrees to the lower right.
Sunday night into Monday morning, October 20 to 21: The planet Jupiter will appear near the waning gibbous Moon. As Jupiter rises on the east-northeastern horizon at 9:08 p.m. EDT, it will be 6 degrees to the lower right of the Moon. As the Moon reaches its highest in the sky at 4:29 a.m., Jupiter will be 6 degrees below the Moon, and it will be to the lower left by the time morning twilight begins at 6:26 a.m.
As mentioned above, the Orionid meteor shower will peak the early morning of Monday, October 21. Conditions are not good as moonlight will interfere with seeing these meteors, but if you happen to be out keep an eye on the sky, as you might see a meteor or two.
For the Washington DC area and similar latitudes, Monday morning, October 21: This will be the last morning Comet C/2024 S1 (ATLAS), visible with binoculars or a telescope (estimated magnitude 11.2), will be above the horizon as morning twilight begins (at 6:27 AM EDT) as it rushes towards its close passage by the Sun a week later.
Monday evening, October 21: This will be the first evening the planet Mercury will be above the west-southwestern horizon 30 minutes after sunset (an estimate of when it will start being visible in the glow of dusk).
Tuesday night into Wednesday morning, October 22 to 23: The waning gibbous Moon, the bright star Pollux, and the planet Mars will form a triangle in the night sky. As Pollux rises on the northeastern horizon at 11 p.m. EDT, it will be 8 degrees to the lower left of the Moon. Mars will rise below the Moon 30 minutes later at 11:30 p.m. As the Moon reaches its highest for the night and morning twilight begins at 6:28 a.m., Pollux will be 4 degrees to the upper left and Mars will be 7 degrees to the lower left of the Moon.
Thursday morning, October 24: The waning Moon will appear half-full as it reaches its last quarter at 4:03 a.m. EDT.
If you find you are having trouble waking up in late October and early November, the dark mornings may be the reason (or at least a plausible excuse). Since 2007 when Congress moved the start of Daylight Saving Time from the end of October to the beginning of November, the latest sunrises of the year have been in late October and early November. In 2024, for the Washington, D.C. area and similar latitudes, the time of sunrise (in EDT) from Thursday, October 24 to Saturday, November 2 will be later than the latest sunrise of winter at 7:27 a.m. EST on January 5.
In the evening sky during this lunar cycle the bright planet Venus will be shifting to the upper left along the southwestern horizon in the opposite direction as the background of stars.
Friday, October 25: This will be when Venus and the bright star Antares will pass at their closest, with Antares 3 degrees to the lower left of Venus.
Saturday morning, October 26: The bright star Regulus will appear below the waning crescent Moon. As Regulus rises on the east-northeastern horizon at 2:15 a.m. EDT, it will be 5 degrees below the Moon. Morning twilight will begin more than 4 hours later at 6:31 a.m. with Regulus 4 degrees to the lower right of the Moon.
Monday morning, October 28: At about 7:39 a.m. EDT, Comet C/2024 S1 (ATLAS) will pass its closest to the Sun. If the sky is very clear, it might be bright enough to see in the daylight for an hour or so around closest approach. For the Washington, D.C. area, closest approach will only be 7 minutes after sunrise, so our only chance of seeing this is if the sky on the east-southeastern horizon is unusually clear. The comet will be to the lower left of the Sun, and since the tail points away from the Sun, it may be hidden by the horizon until the comet rises higher in the sky. Europe, Africa, and South America are better positioned to look for this comet near the Sun. Be careful and plan ahead, as it may be difficult to find a location that has both a clear view to the right part of the east-southeastern horizon and a large overhanging object to block the Sun while allowing you to see to the lower left of the Sun.
Pay attention to the news as the predictions may change, but the brightness predictions I have as of writing this are that this comet will be brighter than magnitude -5 until 8:06 a.m. (when the Sun will be 5.6 degrees above the horizon). Magnitude -4 is generally considered the brightness limit for visibility of an object during the day, and the comet is predicted to be above this magnitude until 8:39 AM, but because it will be close to the Sun it is hard to say what the actual visibility limit will be, as the glare near the Sun depends on atmospheric conditions and can be quite bright.
Tuesday, October 29: At 6:51 p.m. EDT, the Moon will be at apogee, its farthest from the Earth for this orbit.
Thursday morning, October 31: You might be able to see the thin, waxing crescent Moon low on the east-southeastern horizon 3.5 degrees to the lower left of the bright star Spica. You will need to look for them in the glow of dawn, as the Moon will rise at 6:43 a.m. EDT 7 minutes after twilight begins at 6:36 a.m.
Thursday, October 31, is Halloween: We currently divide the year into four seasons based upon the solstices and equinoxes, with winter beginning on the winter solstice in December. 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, and divided the seasons on these days. Using this older definition, winter was the quarter of the year with the shortest daily periods of daylight, with autumn ending and winter beginning on Samhain, traditionally celebrated on October 31st or November 1st (the middle of our fall). Our Halloween customs are thought to have come from these earlier celebrations of fall’s end and winter’s start.
Friday morning, November 1, at 8:47 AM EDT: This will be the new Moon, when the Moon passes between the Earth and the Sun and will not be visible from the Earth. This new Moon is considered the darkest night of the Hindu lunisolar calendar. Diwali or Divali, also known as Dipawali or Deepavali, is an important five or six day festival of lights centered on this new Moon, celebrated by Hindus and other faiths including Jains, Sikhs, and Newar Buddhists. The name comes from the row (avali) of clay lamps (deepa) celebrants light to symbolize the inner light that protects from spiritual darkness. Lakshmi Puja or Kali Puja, venerating the goddess of prosperity, Lakshmi, is the central day of the festival (November 1 this year). It is a public holiday in many countries with large Hindu, Sikh, and/or Jain populations, including Fiji, Guyana, India, Malaysia, Mauritius, Myanmar, Nepal, Pakistan, Singapore, Sri Lanka, Suriname, and Trinidad and Tobago.
The day of or the day after the New Moon: This marks the start of the new month for most lunisolar calendars. The tenth month of the Chinese year of the Dragon starts on Friday, November 1. Sundown on Friday, November 1, marks the start of Marcheshvan in the Hebrew calendar, a name often shortened to Cheshvan or Heshvan.
If Comet C/2024 S1 (ATLAS) survives its close pass by the Sun, Saturday, November 2, will be the first morning it will be above the horizon as morning twilight begins at 6:38 a.m. EDT, appearing with an estimated magnitude of 10.5 (only visible with binoculars or a telescope).
Because of Daylight Saving Time, Saturday morning, November 2, will be the latest sunrise of the year. Morning twilight will begin at 6:38 a.m. EDT, sunrise will be at 7:37 a.m., solar noon will be at 12:51 p.m. when the Sun will reach its maximum altitude of 35.1 degrees, sunset will be at 6:06 p.m., and evening twilight will end at 7:05 p.m.
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 Saturday, November 2, will probably mark the beginning of Jumādā al-ʾŪlā.
Early on Sunday morning, November 3: We “Fall Back” from 1:59 a.m. EDT to 1 a.m. EST. While most of us will be gaining an hour of sleep, if you want to do something for 2 hours but are only supposed to do it for one, consider doing it for the “clock hour” from 1 a.m. EDT to 2 a.m. EST. Be careful though, as about twice as many accidents tend to happen during this “clock hour” compared to other mornings of the year! Regardless, on Sunday morning you will need to reset any clocks that didn’t reset themselves! On Sunday, twilight will begin at 5:39 a.m. EST, sunrise will be at 6:38 a.m., solar noon will be at 11:51 a.m. when the Sun will reach its maximum altitude of 35.8 degrees, sunset will be at 5:05 p.m., and evening twilight will end at 6:04 p.m.
It may be difficult to see, but on Sunday evening, November 3, the bright star Antares will appear 2 degrees above the thin, waxing crescent Moon. You will need to look for the Moon in the glow of dusk as it will set on the southwestern horizon just 1 minute after evening twilight ends (at 6:04 p.m. EST).
Monday evening, November 4: The bright planet Venus will appear 4 degrees to the upper right of the thin, waxing crescent Moon. The Moon will be 6 degrees above the southwestern horizon as evening twilight ends at 6:03 p.m. EST, and will set first 46 minutes later at 6:49 p.m.
Tuesday morning, November 5: Two minor meteor showers, the Southern Taurids (peaking at 7 meteors per hour on November 5) and the Northern Taurids (peaking at 5 meteors per hour on November 12), overlap to produce their highest combined rate. Although the light of the waxing crescent Moon will not interfere, even this combined rate will be low enough to make seeing these meteors from urban areas difficult due to light pollution. Still, if you are out after midnight and the sky is clear, you might see a meteor or two.
Early Saturday morning, November 9: The Moon will appear half-full as it reaches its first quarter at 12:56 a.m. EST.
In the evenings during much of this lunar cycle, the planet Mercury will be shifting to the upper left along the southwestern horizon, moving in the opposite direction from the background of stars. On Saturday and Sunday evenings, November 9 and 10, Mercury and the bright star Antares will pass their closest, less than 2 degrees apart, with Antares to the lower left of Mercury. You will need to look low on the southwestern horizon while dusk is in the sky, as they both will have set by the time evening twilight ends.
Saturday evening into early Sunday morning, November 9 to 10: The planet Saturn will appear near the waxing gibbous Moon. As evening twilight ends at 5:58 p.m. EST, Saturn will be 2 degrees to the upper left. The Moon will reach its highest point for the night about 1 hour 45 minutes later at 7:43 p.m., with Saturn 1 degree to the upper left. For the Washington, D.C. area, Saturn will be at its closest, about 0.1 degree to the upper right of the Moon, at about 9:55 p.m. (times and angles will differ for different locations). For the southern tip if Florida and parts of the Caribbean, Central America, and Northwestern South America, the Moon will block Saturn from view. The Moon will continue passing by Saturn, with Saturn setting first on the western horizon a little less than 3.5 hours later at 1:19 a.m.
Monday evening, November 11: This will be the first evening that the planet Mercury will be above the west-southwestern horizon as evening twilight ends at 5:57 p.m. EST.
Thursday morning, November 14: At 6:18 EST, the Moon will be at perigee, its closest to the Earth for this orbit.
The full Moon after next will be Friday afternoon, November 15, 2024 at 4:29 PM EST. This will be early Saturday morning from Kamchatka and Fiji Time eastwards to the International Date Line. This will be the last of four consecutive supermoons. The Pleiades star cluster will appear near the full Moon. The Moon will appear full for about three days around this time, from a few hours before sunrise Thursday morning into a few hours before sunrise Sunday morning.
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By NASA
7 Min Read NASA’s Webb Reveals Unusual Jets of Volatile Gas from Icy Centaur 29P
An artist’s concept of Centaur 29P/Schwassmann-Wachmann 1’s outgassing activity as seen from the side. Credits:
NASA, ESA, CSA, L. Hustak (STScI) Inspired by the half-human, half-horse creatures that are part of Ancient Greek mythology, the field of astronomy has its own kind of centaurs: distant objects orbiting the Sun between Jupiter and Neptune. NASA’s James Webb Space Telescope has mapped the gases spewing from one of these objects, suggesting a varied composition and providing new insights into the formation and evolution of the solar system.
Centaurs are former trans-Neptunian objects that have been moved inside Neptune’s orbit by subtle gravitational influences of the planets in the last few million years, and may eventually become short-period comets. They are “hybrid” in the sense that they are in a transitional stage of their orbital evolution: Many share characteristics with both trans-Neptunian objects (from the cold Kuiper Belt reservoir), and short-period comets, which are objects highly altered by repeated close passages around the Sun.
Image A: Illustration
An artist’s concept of Centaur 29P/Schwassmann-Wachmann 1’s outgassing activity as seen from the side. While prior radio-wavelength observations showed a jet of gas pointed toward Earth, astronomers used NASA’s James Webb Space Telescope to gather additional insight on the front jet’s composition and noted three more jets of gas spewing from Centaur 29P’s surface. NASA, ESA, CSA, L. Hustak (STScI) Since these small icy bodies are in an orbital transitional phase, they have been the subject of various studies as scientists seek to understand their composition, the reasons behind their outgassing activity — the loss of their ices that lie underneath the surface — and how they serve as a link between primordial icy bodies in the outer solar system and evolved comets.
A team of scientists recently used Webb’s NIRSpec (Near-Infrared Spectrograph) instrument to obtain data on Centaur 29P/Schwassmann-Wachmann 1 (29P for short), an object that is known for its highly active and quasi-periodic outbursts. It varies in intensity every six to eight weeks, making it one of the most active objects in the outer solar system. They discovered a new jet of carbon monoxide (CO) and previously unseen jets of carbon dioxide (CO2) gas, which give new clues to the nature of the centaur’s nucleus.
“Centaurs can be considered as some of the leftovers of our planetary system’s formation. Because they are stored at very cold temperatures, they preserve information about volatiles in the early stages of the solar system,” said Sara Faggi of NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and American University in Washington, DC, lead author of the study. “Webb really opened the door to a resolution and sensitivity that was impressive to us — when we saw the data for the first time, we were excited. We had never seen anything like this.”
Webb and the Jets
Centaurs’ distant orbits and consequent faintness have inhibited detailed observations in the past. Data from prior radio wavelength observations of Centaur 29P showed a jet pointed generally toward the Sun (and Earth) composed of CO. Webb detected this face-on jet and, thanks to its large mirror and infrared capabilities, also sensitively searched for many other chemicals, including water (H2O) and CO2. The latter is one of the main forms in which carbon is stored across the solar system. No indication of water vapor was detected in the atmosphere of 29P, which could be related to the extremely cold temperatures present in this body.
The telescope’s unique imaging and spectral data revealed never-before-seen features: two jets of CO2 emanating in the north and south directions, and another jet of CO pointing toward the north. This was the first definitive detection of CO2 in Centaur 29P.
Image B: IFU Graphic
A team of scientists used NASA’s James Webb Space Telescope’s spectrographic capabilities to gather data on Centaur 29P/Schwassmann-Wachmann 1, one of the most active objects in the outer solar system. The Webb data revealed never-before-seen features: two jets of carbon dioxide spewing in the north and south directions, and a jet of carbon monoxide pointing toward north. NASA, ESA, CSA, L. Hustak (STScI), S. Faggi (NASA-GSFC, American University) Based on the data gathered by Webb, the team created a 3D model of the jets to understand their orientation and origin. They found through their modeling efforts that the jets were emitted from different regions on the centaur’s nucleus, even though the nucleus itself cannot be resolved by Webb. The jets’ angles suggest the possibility that the nucleus may be an aggregate of distinct objects with different compositions; however, other scenarios can’t yet be excluded.
Video A: Zoom and Spin
An artist’s concept of Centaur 29P/Schwassmann-Wachmann 1’s outgassing activity as seen from the side. While prior radio-wavelength observations showed a jet of gas pointed toward Earth, astronomers used NASA’s James Webb Space Telescope to gather additional insight on the front jet’s composition and noted three more jets of gas spewing from Centaur 29P’s surface.
Credit: NASA, ESA, CSA, L. Hustak (STScI) “The fact that Centaur 29P has such dramatic differences in the abundance of CO and CO2 across its surface suggests that 29P may be made of several pieces,” said Geronimo Villanueva, co-author of the study at NASA Goddard. “Maybe two pieces coalesced together and made this centaur, which is a mixture between very different bodies that underwent separate formation pathways. It challenges our ideas about how primordial objects are created and stored in the Kuiper Belt.”
Persisting Unanswered Questions (For Now)
The reasons for Centaur 29P’s bursts in brightness, and the mechanisms behind its outgassing activity through the CO and CO2 jets, continue to be two major areas of interest that require further investigation.
In the case of comets, scientists know that their jets are often driven by the outgassing of water. However, because of the centaurs’ location, they are too cold for water ice to sublimate, meaning that the nature of their outgassing activity differs from comets.
“We only had time to look at this object once, like a snapshot in time,” said Adam McKay, a co-author of the study at Appalachian State University in Boone, North Carolina. “I’d like to go back and look at Centaur 29P over a much longer period of time. Do the jets always have that orientation? Is there perhaps another carbon monoxide jet that turns on at a different point in the rotation period? Looking at these jets over time would give us much better insights into what is driving these outbursts.”
The team is hopeful that as they increase their understanding of Centaur 29P, they can apply the same techniques to other centaurs. By improving the astronomical community’s collective knowledge of centaurs, we can simultaneously better our understanding on the formation and evolution of our solar system.
These findings have been published in Nature.
The observations were taken as part of General Observer program 2416.
The James Webb Space Telescope is the world’s premier space science observatory. Webb is solving mysteries in our solar system, looking beyond to distant worlds around other stars, and probing the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and CSA (Canadian Space Agency).
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Media Contacts
Laura Betz – laura.e.betz@nasa.gov, Rob Gutro – rob.gutro@nasa.gov
NASA’s Goddard Space Flight Center, Greenbelt, Md.
Abigail Major – amajor@stsci.edu, Christine Pulliam – cpulliam@stsci.edu
Space Telescope Science Institute, Baltimore, Md.
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Last Updated Oct 02, 2024 Editor Marty McCoy Contact Laura Betz laura.e.betz@nasa.gov Related Terms
Asteroids Astrophysics Comets Goddard Space Flight Center James Webb Space Telescope (JWST) Science & Research Small Bodies of the Solar System The Solar System View the full article
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