Members Can Post Anonymously On This Site
Elusive Planet Reshapes a Ring Around Neighboring Star
-
Similar Topics
-
By NASA
The ring of light surrounding the center of the galaxy NGC 6505, captured by ESA’s Euclid telescope, is an example of an Einstein ring. NGC 6505 is acting as a gravitational lens, bending light from a galaxy far behind it. ESA/Euclid/Euclid Consortium/NASA, image processing by J.-C. Cuillandre, G. Anselmi, T. Li; CC BY-SA 3.0 IGO or ESA Standard Licence Euclid, an ESA (European Space Agency) mission with NASA contributions, has made a surprising discovery in our cosmic backyard: a phenomenon called an Einstein ring.
An Einstein ring is light from a distant galaxy bending to form a ring that appears aligned with a foreground object. The name honors Albert Einstein, whose general theory of relativity predicts that light will bend and brighten around objects in space.
In this way, particularly massive objects like galaxies and galaxy clusters serve as cosmic magnifying glasses, bringing even more distant objects into view. Scientists call this gravitational lensing.
Euclid Archive Scientist Bruno Altieri noticed a hint of an Einstein ring among images from the spacecraft’s early testing phase in September 2023.
“Even from that first observation, I could see it, but after Euclid made more observations of the area, we could see a perfect Einstein ring,” Altieri said. “For me, with a lifelong interest in gravitational lensing, that was amazing.”
The ring appears to encircle the center of a well-studied elliptical galaxy called NGC 6505, which is around 590 million light-years from Earth in the constellation Draco. That may sound far, but on the scale of the entire universe, NGC 6505 is close by. Thanks to Euclid’s high-resolution instruments, this is the first time that the ring of light surrounding the galaxy has been detected.
Light from a much more distant bright galaxy, some 4.42 billion light-years away, creates the ring in the image. Gravity distorted this light as it traveled toward us. This faraway galaxy hasn’t been observed before and doesn’t yet have a name.
“An Einstein ring is an example of strong gravitational lensing,” explained Conor O’Riordan, of the Max Planck Institute for Astrophysics, Germany, and lead author of the first scientific paper analyzing the ring. “All strong lenses are special, because they’re so rare, and they’re incredibly useful scientifically. This one is particularly special, because it’s so close to Earth and the alignment makes it very beautiful.”
Einstein rings are a rich laboratory for scientists to explore many mysteries of the universe. For example, an invisible form of matter called dark matter contributes to the bending of light into a ring, so this is an indirect way to study dark matter. Einstein rings are also relevant to the expansion of the universe because the space between us and these galaxies — both in the foreground and the background — is stretching. Scientists can also learn about the background galaxy itself.
“I find it very intriguing that this ring was observed within a well-known galaxy, which was first discovered in 1884,” said Valeria Pettorino, ESA Euclid project scientist. “The galaxy has been known to astronomers for a very long time. And yet this ring was never observed before. This demonstrates how powerful Euclid is, finding new things even in places we thought we knew well. This discovery is very encouraging for the future of the Euclid mission and demonstrates its fantastic capabilities.”
A close-up view of the center of the NGC 6505 galaxy, with the bright Einstein ring aligned with it, captured by ESA’s Euclid space telescope.ESA/Euclid/Euclid Consortium/NASA, image processing by J.-C. Cuillandre, G. Anselmi, T. Li; CC BY-SA 3.0 IGO or ESA Standard Licence By exploring how the universe has expanded and formed over its cosmic history, Euclid will reveal more about the role of gravity and the nature of dark energy and dark matter. Dark energy is the mysterious force that appears to be causing the universe’s expansion. The space telescope will map more than a third of the sky, observing billions of galaxies out to 10 billion light-years. It is expected to find around 100,000 strong gravitational lenses.
“Euclid is going to revolutionize the field with all this data we’ve never had before,” added O’Riordan.
Although finding this Einstein ring is an achievement, Euclid must look for a different, less visually obvious type of gravitational lensing called “weak lensing” to help fulfil its quest of understanding dark energy. In weak lensing, background galaxies appear only mildly stretched or displaced. To detect this effect, scientists will need to analyze billions of galaxies.
Euclid launched from Cape Canaveral, Florida, July 1, 2023, and began its detailed survey of the sky Feb. 14, 2024. The mission is gradually creating the most extensive 3D map of the universe yet. The Einstein ring find so early in its mission indicates Euclid is on course to uncover many more secrets of the universe.
More About Euclid
Euclid is a European mission, built and operated by ESA, with contributions from NASA. The Euclid Consortium — consisting of more than 2,000 scientists from 300 institutes in 15 European countries, the United States, Canada, and Japan — is responsible for providing the scientific instruments and scientific data analysis. ESA selected Thales Alenia Space as prime contractor for the construction of the satellite and its service module, with Airbus Defence and Space chosen to develop the payload module, including the telescope. Euclid is a medium-class mission in ESA’s Cosmic Vision Programme.
Three NASA-supported science teams contribute to the Euclid mission. In addition to designing and fabricating the sensor-chip electronics for Euclid’s Near Infrared Spectrometer and Photometer (NISP) instrument, NASA’s Jet Propulsion Laboratory led the procurement and delivery of the NISP detectors as well. Those detectors, along with the sensor chip electronics, were tested at NASA’s Detector Characterization Lab at Goddard Space Flight Center in Greenbelt, Maryland. The Euclid NASA Science Center at IPAC (ENSCI), at Caltech in Pasadena, California, will archive the science data and support U.S.-based science investigations. JPL is a division of Caltech.
Media Contacts
Elizabeth Landau
Headquarters, Washington
202-358-0845
elandau@nasa.gov
Calla Cofield
Jet Propulsion Laboratory, Pasadena, Calif.
626-808-2469
calla.e.cofield@jpl.nasa.gov
View the full article
-
By European Space Agency
Euclid, the European Space Agency’s dark Universe detective, has made an astonishing discovery – right in our cosmic backyard.
View the full article
-
By NASA
5 Min Read Planetary Alignments and Planet Parades
A sky chart showing Mars, Jupiter, Saturn, and Venus in a “planet parade.” Credits:
NASA/JPL-Caltech On most nights, weather permitting, you can spot at least one bright planet in the night sky. While two or three planets are commonly visible in the hours around sunset, occasionally four or five bright planets can be seen simultaneously with the naked eye. These events, often called “planet parades” or “planetary alignments,” can generate significant public interest. Though not exceedingly rare, they’re worth observing since they don’t happen every year.
Why Planets Appear Along a Line in The Sky
“Planet parade” isn’t a technical term in astronomy, and “planetary alignment” can refer to several different phenomena. As the planets of our solar system orbit the Sun, they occasionally line up in space in events called oppositions and conjunctions. A planetary alignment can also refer to apparent lineups in our sky with other planets, the Moon, or bright stars.
The planets of our solar system always appear along a line on the sky. This line, referred to as the ecliptic, represents the plane in which the planets orbit, seen from our position within the plane itself. NASA/Preston Dyches When it comes to this second type of planetary alignment, it’s important to understand that planets always appear along a line or arc across the sky. This occurs because the planets orbit our Sun in a relatively flat, disc-shaped plane. From Earth, we’re looking into that solar system plane from within. We see the racetrack of the planets from the perspective of one of the racers ourselves. When viewed edge-on, this disc appears as a line, which we call the ecliptic or ecliptic plane.
So, while planet alignment itself isn’t unusual, what makes these events special is the opportunity to observe multiple planets simultaneously with the naked eye.
Will the Planets Actually be Visible?
Before preparing to observe a planet parade, we have to consider how high the planets will appear above the horizon. For most observers to see a planet with the naked eye, it needs to be at least a few degrees above the horizon, and10 degrees or higher is best. This is crucial because Earth’s atmosphere near the ground dims celestial objects as they rise or set. Even bright planets become difficult or impossible to spot when they’re too low, as their light gets scattered and absorbed on its path to your eye. Buildings, trees, and other obstructions often block the view near the horizon as well.
This visibility challenge is particularly notable after sunset or before sunrise, where the sky is still glowing. If a planet appears very low within the sunset glow, it is very difficult to observe.
The Planets You Can See, and Those You Can’t
Five planets are visible without optical aid: Mercury, Venus, Mars, Jupiter, and Saturn. Ancient civilizations recognized these worlds as bright lights that wandered across the starscape, while the background stars remained fixed in place. In fact, the word “planet” comes to us from the Greek word for “wanderer.”
The solar system includes two additional major planets, Uranus and Neptune, plus numerous dwarf planets like Pluto and Ceres. Uranus and Neptune orbit in the dim, cold depths of the outer solar system. Neptune absolutely requires a telescope to observe. While Uranus is technically bright enough to detect with good eyesight, it’s quite faint and requires dark skies and precise knowledge of its location among similarly faint stars, so a telescope is recommended. As we’ll discuss in the next section, planet parades necessarily must be observed in twilight before dawn or after sunset, and this is not a good time to try observing extremely faint objects like Uranus and Neptune.
Thus, claims about rare six- or seven-planet alignments which include Uranus and Neptune should be viewed with the understanding that these two distant planets will not be visible to the unaided eye.
What Makes Multi-Planet Lineups Special
Lineups of four or five planet naked-eye planets with optimal visibility typically occur every few years. Mars, Jupiter, and Saturn are frequently seen in the night sky, but the addition of Venus and Mercury make four- and five-planet lineups particularly noteworthy. Both orbit closer to the Sun than Earth, with smaller, faster orbits than the other planets. Venus is visible for only a couple of months at a time when it reaches its greatest separation from the Sun (called elongation), appearing just after sunset or before sunrise. Mercury, completing its orbit in just 88 days, is visible for only a couple of weeks (or even a few days) at a time just after sunset or just before sunrise.
Planet parades aren’t single-day events, as the planets move too slowly for that. Generally, multi-planet viewing opportunities last for weeks to a month or more. Even five-planet events last for several days as Mercury briefly emerges from and returns to the Sun’s glare.
In summary, while they aren’t once-in-a-lifetime events, planetary parades afford an uncommon opportunity to look up and appreciate our place in our solar system, with diverse worlds arrayed across the sky before our very eyes.
Other Planet Lineups
Other recent and near-future multi-planet viewing opportunities:
January 2016 – Four planets visible at once before sunrise Late April to Late August 2022 – Four planets visible at once before sunrise Mid-June to Early July 2022 – Five planets visible at once before sunrise January to mid-February 2025 – Four planets visible at once after sunset Late August 2025 – Four planets visible at once before sunrise Late October 2028 – Five planets visible at once before sunrise Late February 2034 – Five planets visible at once after sunset (Venus and Mercury challenging to observe) About the January/February 2025 Planet Parade
The current four-planet lineup concludes by mid-February, as Saturn sinks increasingly lower in the sky each night after sunset. By mid-to-late February, Saturn appears less than 10 degrees above the horizon as sunset fades, making it difficult to observe for most people. While Mercury briefly joins Saturn in the post-sunset glow at the end of February, both planets will be too low and faint for most observers to spot.
Keep Exploring Discover More Topics From NASA
Skywatching
Planets
Solar System Exploration
Moons
View the full article
-
-
-
-
Check out these Videos
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.