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ESA’s Cheops finds an unexpected ring around dwarf planet Quaoar
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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.
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By European Space Agency
Euclid, the European Space Agency’s dark Universe detective, has made an astonishing discovery – right in our cosmic backyard.
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By NASA
5 min read
NASA CubeSat Finds New Radiation Belts After May 2024 Solar Storm
Key Points
The May 2024 solar storm created two new temporary belts of high-energy particles surrounding Earth. Such belts have been seen before, but the new ones were particularly long lasting, especially the new proton belt. The findings are particularly important for spacecraft launching into geostationary orbits, which can be damaged as they traverse the dangerous belts. The largest solar storm in two decades hit Earth in May 2024. For several days, wave after wave of high-energy charged particles from the Sun rocked the planet. Brilliant auroras engulfed the skies, and some GPS communications were temporarily disrupted.
With the help of a serendipitously resurrected small NASA satellite, scientists have discovered that this storm also created two new temporary belts of energetic particles encircling Earth. The findings are important to understanding how future solar storms could impact our technology.
The new belts formed between two others that permanently surround Earth called the Van Allen Belts. Shaped like concentric rings high above Earth’s equator, these permanent belts are composed of a mix of high-energy electrons and protons that are trapped in place by Earth’s magnetic field. The energetic particles in these belts can damage spacecraft and imperil astronauts who pass through them, so understanding their dynamics is key to safe spaceflight.
The May 2024 solar storm created two extra radiation belts, sandwiched between the two permanent Van Allen Belts. One of the new belts, shown in purple, included a population of protons, giving it a unique composition that hadn’t been seen before. NASA/Goddard Space Flight Center/Kristen Perrin The discovery of the new belts, made possible by NASA’s Colorado Inner Radiation Belt Experiment (CIRBE) satellite and published Feb. 6, 2025, in the Journal of Geophysical Research: Space Physics, is particularly important for protecting spacecraft launching into geostationary orbits, since they travel through the Van Allen Belts several times before reaching their final orbit.
New Belts Amaze Scientists
Temporary belts have been detected in the aftermath of large solar storms before. But while previous belts have been composed mostly of electrons, the innermost of the two new belts also included energetic protons. This unique composition is likely due to the strength and composition of the solar storm.
“When we compared the data from before and after the storm, I said, ‘Wow, this is something really new,’” said the paper’s lead author Xinlin Li, a professor at the Laboratory for Atmospheric and Space Physics (LASP) and Department of Aerospace Engineering Sciences at the University of Colorado Boulder. “This is really stunning.”
The new belts also seem to have lasted much longer than previous belts. Whereas previous temporary belts lasted around four weeks, the new belt composed primary of electrons lasted more than three months. The other belt, that also includes protons, has lasted much longer than the electron belt because it is in a more stable region and is less prone to the physical processes that can knock the particles out of orbit. It is likely still there today.
“These are really high-energy electrons and protons that have found their way into Earth’s inner magnetic environment,” said David Sibeck, former mission scientist for NASA’s Van Allen Probes and research scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, who was not involved with the new study. “Some might stay in this place for a very long time.”
How long such belts stick around depends on passing solar storms. Large storms can provide the energy to knock particles in these belts out of their orbits and send them spiraling off into space or down to Earth. One such storm at the end of June significantly decreased the size of the new electron belt and another in August nearly erased the remainder of that electron belt, though a small population of high-energy electrons endured.
CubeSat Fortuitously Comes Back to Life to Make the Discovery
The new discovery was made by NASA’s CIRBE satellite, a CubeSat about the size of a shoebox that circled the planet’s magnetic poles in a low Earth orbit from April 2023 to October 2024. CIRBE housed an instrument called the Relativistic Electron Proton Telescope integrated little experiment-2 (REPTile-2) — a miniaturized and upgraded version of an instrument that flew aboard NASA’s Van Allen Probes, which made the first discovery of a temporary electron belt in 2013.
The CIRBE CubeSat in the laboratory before launch. CIRBE was designed and built by LASP at the University of Colorado Boulder. Xinlin Li/LASP/CU Boulder After a year in space, the CubeSat experienced an anomaly and unexpectedly went quiet on April 15, 2024. The scientists were disappointed to miss the solar storm in May but were able to rely on other spacecraft to provide some preliminary data on the electron belt. Luckily, on June 15, the spacecraft sprang back to life and resumed taking measurements. The data provided high-resolution information that couldn’t be gleaned by any other instrument and allowed the scientists to understand the magnitude of the new belts.
“Once we resumed measurements, we were able to see the new electron belt, which wasn’t visible in the data from other spacecraft,” Li said.
Having the CubeSat in orbit to measure the effect of the solar storm has been bittersweet, Li said. While it provided the opportunity to measure the effects of such a large event, the storm also increased atmospheric drag on the CubeSat, which caused its orbit to decrease prematurely. As a result, the CubeSat deorbited in October 2024. However, the spacecraft’s data makes it all worth it.
“We are very proud that our very small CubeSat made such a discovery,” Li said.
CIRBE was designed and built by LASP at the University of Colorado Boulder and was launched through NASA’s CubeSat Launch Initiative (CSLI). The mission is sponsored by NASA’s Heliophysics Flight Opportunities for Research & Technology (H-FORT) program.
By Mara Johnson-Groh
NASA’s Goddard Space Flight Center, Greenbelt, Md.
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Last Updated Feb 06, 2025 Related Terms
Heliophysics CubeSats Goddard Space Flight Center Heliophysics Division Ionosphere Space Weather The Sun Van Allen Probes Explore More
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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.
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