Tag Archives: Astronomical objects

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How to See the ‘Green Comet’ Everyone’s Talking About

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Deep in the Stone Age, when Neanderthals still lived alongside Homo sapiens, our ancestors might have been agog at a green light in the night sky. Now, that light—C/2022 E3 (ZTF) (more familiarly, the Green Comet)—is back.

The Green Comet’s highly elliptical orbit means it will take a long time for it to swing past Earth again—about 50,000 years, to be specific. And that’s if it repeats its 50,000-year sojourn, which it may not.

Astronomers discovered the comet in March 2022 using the Samuel Oschin robotic telescope at the Zwicky Transient Facility. It passed perihelion (when it is closest to the Sun) on January 12.

Observers in the U.S. can see the comet now through early February, potentially with the naked eye if you’re in a dark viewing area, but your chances will be better using binoculars or a telescope. The best time to see the comet is in the predawn hours, according to NASA.

The comet will make its closest approach to our planet on February 2. The closest approach will take it about 0.29 AU (about 27 million miles) from Earth, according to EarthSky.

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Currently, the comet is toward the constellation Boötes and near Hercules, EarthSky reports. (If you’re having trouble finding the comet’s position, you can consult a handy interactive sky chart.) The comet’s location makes it difficult for observers in the Southern Hemisphere to see. From its current location in the night sky, its projected path charts it past Ursa Minor (the Little Dipper), with it passing by Camelopardis at the time of its closest approach.

Comets glow thanks to a combination of their chemical composition and sunlight. Comets that pass near the Sun are illuminated and warmed by its energy, causing molecules on their surface to evaporate and fluoresce. Comet heads glow green when they contain cyanogen or diatomic carbon, according to NASA.

The Green Comet may get as bright as magnitude 5 by the time it’s closest to Earth, according to EarthSky. The lower the number, the brighter the object. The full Moon’s apparent magnitude is about -11, and the faintest objects seen by the Hubble Space Telescope are about magnitude 30, according to Brittanica. The dimmest stars that our naked eye can see are about magnitude 6.

While the comet may reach a brightness of magnitude 5, it’ll probably be helpful to use a pair of binoculars or a telescope if you’re having difficulty spotting the object on a clear night.

The incoming space rock is not the only recent green comet; in 2018, the comet 46P/Wirtanen was bright enough for observers to see with the naked eye, and in 2021, the Comet Leonard glowed green as the ice-ball made its cosmic trajectory.

So keep your eyes up on the clear nights to come. If you see something with a faint green glow, it’s probably our newest cosmic visitor.

More: Mega Comet Arriving From the Oort Cloud Is 85 Miles Wide

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Webb Telescope Reveals a Luminous Stellar Crime Scene

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2,500 years ago, one of space’s most beautiful features was born: the Southern Ring Nebula. The nebula was vividly imaged by the Webb Space Telescope earlier this year, and astronomers now think they know exactly how a star’s violent outburst occurred, leaving the elegant nebula in its wake.

The star that bore the nebula was about three times the size of the Sun and 500 million years old. That’s quite young, in stellar terms; our Sun is about 4.6 billion years old and should live for another 5 billion.

Around 2,500 years ago, Confucius and the Buddha were still alive. The Peloponnesian Wars were about to kick off. And somewhere in those intervening years, a star 2,000 light-years away expired, blasting gas outward from a newly formed white dwarf.

The Southern Ring Nebula’s star is not dead—not yet—but its expulsion of gas is a major turning point in the star’s lifespan. White dwarfs are the stellar endgame; they form when stars have exhausted their nuclear energy and begin their slow cooldown.

Thanks to images from the Webb Space Telescope and clever calculations and mathematical modeling by the research team, the moments preceding the Southern Ring Nebula’s stellar light show can now be examined in detail.

Different Webb filters highlight various aspects of a light source, which is why some parts of the nebula may look pearlescent or a translucent red while others look blue or orange, depending on the image. The Webb image processors choose to highlight different aspects of objects in order to showcase various elements—hot gas, for example, or star factories within larger systems.

A team of 70 astronomers worked together to determine that as many as five stars (only two of which are now visible) may have been involved in the stellar demise. Their investigation of the star’s death is published today in Nature Astronomy.

“We were surprised to find evidence of two or three companion stars that probably hastened its death as well as one more ‘innocent bystander’ star that got caught up in the interaction,” said Orsola De Marco, an astronomer at Macquarie University and the study’s lead author, in a university release.

The team’s play-by-play of the nebula’s origins was possible thanks to very precise measurements of the most brilliant star (the star among stars, if you will) in the Webb image. Webb data enabled the researchers to precisely measure its mass and how far along in its own life it is, which in turn allowed them to derive the mass of the central faint star before it shed its material and created the colorful nebula.

Webb imaged the Southern Ring with two instruments, NIRcam and MIRI. The Webb images were supplemented by data from the European Southern Observatory’s Very Large Telescope, the San Pedro de Mártir Telescope, and NASA’s Gaia and Hubble space telescopes.

Only two of the stars thought to be involved in this cosmic rager are visible in Webb’s representative color snapshot of the nebula, taken with NIRcam. The bright star in the nebula’s center is partnered to the one that ejected so much material that it became a white dwarf. That wizened (and exhausted) star sits faintly along the 8 o’clock diffraction spike of the bright central star in the image above.

The astronomers believe that at least one star interacted with the fainter star (star 1 in the illustrated timeline below) as the latter swelled up, preparing to expel its gas and become a white dwarf.

According to the team, that mystery star (star 3) spewed out jets of material as it interacted with the dying star and cloaked the faint star in dust before merging with the dwarf. Star 2 in the illustration is the bright spot at the center of the nebula now—a comparatively stalwart character, given its lack of explosive activity or gassy releases.

Another star (or ‘partygoer’, in the Space Telescope Science Institute’s analogy of an astrophysical fête gone wrong) kicked up the gas and dust let loose by its predecessor, causing wavy ripples in the material. Then, another star (star 5 in the panels above) circled the light show and produced the ring system encircling the nebula.

By the researchers’ reckoning, you can consider the white dwarf near the nebula’s core to be the party host that raged way too hard and passed out well before the party’s end. But the star showed everyone a great time while it was up for it, and it’s thanks to it that the party lived on.

“We think all that gas and dust we see thrown all over the place must have come from that one star, but it was tossed in very specific directions by the companion stars,” said Joel Kastner, an astrophysicist at the Rochester Institute of Technology, in an StScI release.

The researchers believe the same methods that uncovered specifics of the Southern Ring Nebula’s birth could help unpack the births of other nebulae, as well as the astrophysical forces at work in the interactions of stars.

The imagery that unveiled this interstellar scene was published in June; only now have researchers had the time to sift through the data and present their interpretation of it.

So, consider the images you’ve seen from Webb thus far—they all have their own stories, which will (hopefully) soon be told in detail.

More: Are the Colors in Webb Telescope Images ‘Fake’?

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Science

An Ancient Asteroid Impact May Have Caused a Megatsunami on Mars

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The Viking 1 lander arrived on the Martian surface 46 years ago to investigate the planet. It dropped down into what was thought to be an ancient outflow channel. Now, a team of researchers believes they’ve found evidence of an ancient megatsunami that swept across the planet billions of years ago, less than 600 miles from where Viking landed.

In a new paper published today in Scientific Reports, a team identified a 68-mile-wide impact crater in Mars’ northern lowlands that they suspect is leftover from an asteroid strike in the planet’s ancient past.

“The simulation clearly shows that the megatsunami was enormous, with an initial height of approximately 250 meters, and highly turbulent,” said Alexis Rodriguez, a researcher at the Planetary Science Institute and lead author of the paper, in an email to Gizmodo. “Furthermore, our modeling shows some radically different behavior of the megatsunami to what we are accustomed to imagining.”

Rodriguez’s team studied maps of the Martian surface and found the large crater, now named Pohl. Based on Pohl’s position on previously dated rocks, the team believes the crater is about 3.4 billion years old—an extraordinarily long time ago, shortly after the first signs of life we know of appeared on Earth.

According to the research team’s models, the asteroid impact could have been so intense that material from the seafloor may have dislodged and been carried in the water’s debris flows. Based on the size of the crater, the team believes the impacting asteroid could have been 1.86 miles wide or 6 miles wide, depending on the amount of ground resistance the asteroid encountered.

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The impact could have released between 500,000 megatons and 13 million megatons of TNT energy (for comparison, the Tsar Bomba nuclear test was about 57 megatons of TNT energy.)

“A clear next step is to propose a landing site to investigate these deposits in detail to understand the ocean’s evolution and potential habitability,” Rodriguez said. “First, we would need a detailed geologic mapping of the area to reconstruct the stratigraphy. Then, we need to connect the surface modification history to specific processes through numerical modeling and analog studies, including identifying possible mud volcanoes and glacier landforms.”

Both lines of investigation are noble pursuits, but it may be some time before a new Mars lander gets off the ground. NASA is always juggling missions, but its main planetary focus in the future is Venus. The DAVINCI+ and Veritas missions would see two spacecraft arrive at the second planet from the Sun at the turn of the decade.

There are no plans for a future Mars lander, besides the Mars Sample Return mission, which will retrieve the rock core samples currently being extracted by the Perseverance rover on the western edge of the planet’s Jezero Crater.

NASA is canceling and delaying missions as it deals with a budget crunch, so exactly when the agency could turn its attention to the Pohl crater is unclear. With the InSight lander on its last legs, we will soon lose one of our best interrogators of the Martian interior.

More: Stunning New View of Mars Shows Where Ancient Flowing Water Once Carved Its Surface

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NASA Probe Captures Haunting Images of Earth and Moon

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The Lucy spacecraft captured this image of Earth on October 15.
Image: NASA

NASA’s Lucy spacecraft got its first view of the Earth-Moon system one year after launching from its home planet to explore a distant swarm of asteroids. The spacecraft captured beautiful, and somewhat daunting, images of Earth and its natural satellite as it whizzed past for a gravitational assist.

The Lucy spacecraft is currently on a six-year journey to Jupiter to study the Trojan asteroids, two groups of rocky bodies that lead and follow Jupiter as it orbits the Sun.

As part of its convoluted journey, Lucy flew by Earth on October 15 for the first of three gravity assist maneuvers to place the spacecraft on a new trajectory beyond the orbit of Mars. During its flyby, Lucy took a few photos of Earth and the Moon to calibrate the spacecraft’s instruments. NASA released the images this week—and they’re really great, if not a bit goosebump-inducing. What’s more, they’re a sneak preview into the capabilities of the spacecraft and the kinds of views can expect of the Trojan asteroids.

Image: NASA

The first image was taken on October 13, when Lucy was 890,000 miles (1.4 million kilometers) away from Earth. The spacecraft was still making its way towards our planet for the close flyby and was able to capture the Earth-Moon system in the same frame.

The Moon can be seen very faintly along the left side of the image, separated from its host planet by about 238,900 miles (384,400 kilometers). This view of the distant pair defies our perception of the Moon that we see in our night skies, which appears relatively close to us. Instead, the image reveals how far the Moon really is from Earth, and the eerie darkness of space between them.

Image: NASA

As Lucy got closer to Earth, it captured this closer look at the planet on October 15 at a distance of 385,000 miles (620,000 kilometers). This view of the Earth shows Hadar, Ethiopia—the place of origin for the 3.2 million-year-old hominid fossil that the spacecraft was named after.

The Lucy fossils provided valuable insights into human evolution, the same way the Trojan asteroids could help scientists piece together the origin story of the early solar system and how it evolved over time.

Image: NASA

Roughly eight hours after it flew past Earth, Lucy got snugly with the Moon. The spacecraft captured this closeup image of the lunar surface on October 16 at a distance of around 140,000 miles (230,000 km) from the surface.

The image, taken with Lucy’s L’LORRI (Lucy LOng Range Reconnaissance Imager) high-resolution greyscale camera, was put together by combining ten separate two millisecond exposures of the same frame to increase its quality, with each pixel representing about 0.8 miles (1.3 kilometers).

Image: NASA

This mosaic of the Moon was created from five separate one millisecond exposures, with each pixel representing about 0.7 miles (1.2 kilometers). The uppermost area of the image was taken at an earlier time than the bottom, resulting in the incongruous view of this lunar area. The image was taken about eight hours after Lucy’s flyby of Earth, when the spacecraft was around 140,000 miles (230,000 km) away from the Moon.

Image: NASA

In another closeup image of the Moon, Lucy observed the side of the lunar surface most familiar to us on Earth. Flying between the Earth and Moon, the spacecraft captured the lava-filled impact basin Mare Imbrium. The lower-right area of the image shows the Apennine mountain range—the landing site for the Apollo 15 mission in 1971.

After Lucy bid farewell to Earth, its new trajectory placed it on a two-year orbit around the Sun. In two years, Lucy will return to Earth for yet another gravity assist. From there, the spacecraft will still have about three years to go before reaching its first target, asteroid Donaldjohanson. Later in August 2027, Lucy will begin its Trojan tour by visiting Eurybates and its binary partner Queta, followed by Polymele and its binary partner, Leucus, Orus, and the binary pair Patroclus and Menoetius.

More: Astronomers Chase Shadows From Jupiter’s Mysterious Trojan Asteroids

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Close-Up Photo of Jupiter’s Moon Europa Shows a Bizarre Surface

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NASA’s Juno spacecraft took images of Jupiter’s icy moon Europa during a recent flyby. One of the photos—released this week by NASA—offers an intimate view of Europa’s surface features.

Juno has orbited the gas giant Jupiter since 2016, but only recently has NASA diverted the spacecraft’s attention to the planet’s moons. Europa is of particular scientific interest because scientists believe a salty ocean lies beneath the moon’s frozen surface.

If such an ocean is there—something the upcoming Europa Clipper mission will investigate using surface-penetrating radar—it could host ingredients for life, if not life itself.

The recent image was taken during Juno’s flyby on September 29, during which the spacecraft came within about 220 miles of the moon’s surface. The image covers a roughly 11,600-square-mile swath of Europa, a region dominated with grooves and ridges in the ice. It’s a black-and-white photo taken from about 256 miles above the surface and is the highest-resolution image taken of a specific portion of the moon.

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The new pic builds on the first images released from the flyby. Darker splotches on the ice could indicate something beneath the moon’s crust erupting onto the surface, according to a recent NASA release. White flecks dotting the image are signatures of high-energy particles from the radiation in the moon’s surrounding environment.

“These features are so intriguing,” said Heidi Becker, the lead co-investigator for the camera used to take the image, in the release. “Understanding how they formed – and how they connect to Europa’s history – informs us about internal and external processes shaping the icy crust.”

Though Juno began its focus on Jupiter, its investigation has expanded to that of four Galilean satellites and the gas giant’s rings—not so easily seen, but recently captured in images by the Webb Space Telescope.

Juno flew by Ganymede (the largest moon in the solar system) in June 2021, and in 2023 Io will get its own flyby. Juno is significantly expanding its observational targets and will be supplanted in the early 2030s by NASA’s Europa Clipper, which will investigate Europa’s ability to foster life with state-of-the-art instruments.

Europa’s surface may look pretty hostile in black and white and from 200 miles up, but beneath the ice, it could be an entirely different story.

More: Check Out Juno’s First Up-Close Images of Icy Europa

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Our Earliest Close-Ups of the Planets Versus Today’s Best Shots

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Left: Pioneer 10’s view of Jupiter in March 1973. Right: Webb Telescope’s view of Jupiter in July 2022.
Image: NASA, ESA, CSA, Jupiter ERS Team; image processing by Judy Schmidt

For centuries, astronomers were limited to ground-based observations of the planets, but now we use spacecraft to capture close-up views of our neighboring worlds. Excitingly, our views of solar system planets have been getting progressively better over the decades, as these images attest.

The dawn of the Space Age finally made it possible for humankind to capture close-up views of astronomical objects. We haven’t wasted this opportunity, sending probes to every planet in our solar system and even to Pluto, a dwarf planet located over 5 billion miles (8 billion kilometers) away.

The first missions to the planets began in the 1960s, and it’s something we still get excited about. We’ve assembled a series of photos showing some of our earliest images of the planets compared to similar portraits captured during recent missions. Regardless of the era or the quality, each one has a story to tell, and each continues to stir the imagination.

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New Map of Mars Shows Where It Was Once Covered in Water

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A map of hydrated mineral deposits on Mars. Green represents hydrated sulphates; red is hydrous clays; orange is carbonate salts; and blue is hydrated silica and aluminosilicate clays.

The history of water on Mars flows a lot deeper than scientists once believed. A new project has mapped hundreds of thousands of rock formations on the Red Planet that may have been altered by large amounts of water in the past.

Data from two Mars orbiters was used to create a detailed global map of mineral deposits on Mars, pinpointing where water may have once flowed across the planet. “I think we have collectively oversimplified Mars,” planetary scientist John Carter from the Institut d’Astrophysique Spatiale in Paris, and lead author of a paper published in the journal Icarus, said in a statement.

Observations from the European Space Agency’s Mars Express orbiter and NASA’s Mars Reconnaissance Orbiter allowed researchers to create the map, a project that took a decade, according to the ESA. Before this work, scientists only knew of about 1,000 rock formations on Mars that contain hydrated minerals. But the new map reveals hundreds of thousands of such outcrops. “This work has now established that when you are studying the ancient terrains in detail, not seeing these minerals is actually the oddity,” said Carter.

This image shows hydrated minerals at Jezero Crater (the larger red and orange area at upper left) and Gale Crater (small green circle at middle right). Both craters have been explored by robotic rovers.
Image: ESA/Mars Express (OMEGA) and NASA/Mars Reconnaissance Orbiter (CRISM)

Mars is a dry planet today, but various evidence suggests it once had flowing water across its surface. Aqueous minerals can be found in rocks that were chemically altered by water in the past, and typically turned into clays and salts. When small amounts of water interact with the rocks, they remain relatively unchanged and retain the same minerals found in the original volcanic rocks. But if large amounts of water interact with the rocks, then soluble elements are dissolved by the water, leaving behind more aluminum-rich clays.

The new findings suggest that water played a much bigger role in shaping Mars’ geology over the course of its history. However, it’s still not clear whether the presence of water was consistent over time or if there was an ebb and flow of water on Mars over shorter periods in its early history. “The evolution from lots of water to no water is not as clear cut as we thought, the water didn’t just stop overnight,” said Carter. “We see a huge diversity of geological contexts, so that no one process or simple timeline can explain the evolution of the mineralogy of Mars.”

Although the map doesn’t provide all the answers, it does point to places where more clues can be found. The areas identified here will be excellent candidate landing sites for future missions to Mars; some of them may even still have water ice buried beneath the surface.

More: Mars Is Hiding Its ‘Lost’ Water Beneath the Surface, New Research Suggests

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Japan Wants to Bring Artificial Gravity to the Moon

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Lunar Glass is the proposed project that will simulate gravity through centrifugal force.
Gif: Kajima Corporation/Gizmodo

Interest in the Moon has been reignited recently, and Japan is looking to get in on the fun. Researchers and engineers from Kyoto University and the Kajima Corporation have released their joint proposal for a three-pronged approach to sustainable human life on the Moon and beyond.

The future of space exploration will likely include longer stays in low gravity environments, whether in orbit or on the surface of another planet. Problem is, long stays in space can wreak havoc on our physiology; recent research shows that astronauts can suffer a decade of bone loss during months in space, and that their bones never return to normal. Thankfully, researchers from Kyoto University and the Kajima Corporation are seeking to engineer a potential solution.

The proposal, announced in a press release last week, looks like something ripped straight from the pages of a sci-fi novel. The plan consists of three distinct elements, the first of which, called “The Glass,” aims to bring simulated gravity to the Moon and Mars through centrifugal force.

02　ルナグラスと交通機関

Gravity on the Moon and Mars is about 16.5% and 37.9% of that on Earth, respectively. Lunar Glass and Mars Glass could bridge that gap; they are massive, spinning cones that will use centrifugal force to simulate the effects of Earth’s gravity. These spinning cones will have an approximate radius of 328 feet (100 meters) and height of 1,312 feet (400 meters), and will complete one rotation every 20 seconds, creating a 1g experience for those inside (1g being the gravity on Earth). The researchers are targeting the back half of the 21st century for the construction of Lunar Glass, which seems unreasonably optimistic given the apparent technological expertise required to pull this off.

The second element of the plan is the “core biome complex” for “relocating a reduced ecosystem to space,” according to a Google-translated version of the press release. The core biome complex would exist within the Moon Glass/Mars Glass structure and it’s where the human explorers would live, according to the proposal. The final element of the proposal is the “Hexagon Space Track,” or Hexatrack, a high-speed transportation infrastructure that could connect Earth, Mars, and the Moon. Hexatrack will require at least three different stations, one on Mars’s moon Phobos, one in Earth orbit, and one around the Moon (likely the planned Lunar Gateway).

The journey back to the Moon is getting nearer while interest in settling Mars is growing. A major obstacle in the way of long-term stays on these bodies is gravity. The proposal from Kyoto University and the Kajima Corporation is exciting and promising, but it’s not something we should expect any time soon.

More: NASA’s CAPSTONE Probe Is Officially en Route to the Moon

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How (and When) to Watch the Massive K2 Comet Pass Earth

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Photo: Jim Cumming (Shutterstock)

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What is K2?

The comet C/2017 K2 (PanSTARRS)—or “K2″ for short—was first spotted five years ago, in May 2017 by the Hubble Space Telescope, NASA reports. The agency shared an image of the comet taken on June 20th, 2022, when it was (relatively) near open star cluster IC 4665 and bright star Beta Ophiuchi, near a starry edge of the Milky Way.

This is the first time the K2 comet has made its way to the inner Solar System from the dim and distant Oort cloud, NASA explains. When it was first observed in May 2017, it was the most distant active inbound comet ever discovered—roughly 2.4 billion kilometers from the Sun, between the orbital distances of Uranus and Saturn.

How big is K2?

When the K2 comet first became visible on the Hubble Space Telescope, scientists estimated that it had a nucleus nearly 11 miles in diameter. But according to research from the Canada-France-Hawaii Telescope, the comet’s nucleus is estimated to have a radius between nine and 50 miles. Either way, it’s pretty damn big.

And that’s not counting the size of K2’s tail—the trail of gasses and dust behind the comet—also known as a “coma.” According to early estimates, K2’s tail is anywhere between 81,000 and 500,000 miles across. For some perspective, that’s somewhere between the width of one and six Jupiters.

When will K2 be visible?

Your best chance of seeing the K2 comet will be the night of July 14th, which is when it will make its closest approach to Earth. Even though it’s huge, you’ll likely need at least a small telescope to spot the comet. Look for a fuzzy patch of light (which is the tail).

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If you’d prefer to watch the comet pass Earth from the comfort of your own home, the Virtual Telescope Project will be live-streaming it starting at 6.15 pm on July 14. But don’t worry too much if you miss K2 on the 14th—it should be visible with a telescope until September.

The closest it will get to the Sun will be in December.

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The Coolest Images Taken by NASA’s New Horizons Spacecraft

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Artist’s impression of New Horizons.
Image: NASA/JHUAPL/SwRI

NASA’s New Horizons spacecraft has seen amazing things since it launched over sixteen years ago. It has cruised by Jupiter, peeked at erupting volcanos on Io, and most famously, zipped past Pluto, becoming the first spacecraft to visit a dwarf planet.

The spacecraft is now about 4.3 billion miles (6.9 billion km) from Earth, where it is operating normally and venturing deep into the Kuiper belt at speeds reaching 33,000 miles per hour (53,000 km/hr).

The Pluto flyby, which occurred on July 14, 2015, remains the probe’s crowning achievement. But scientists have taken full advantage of the NASA mission’s journey through the solar system to capture thousands of images of solar system objects. These are our favorites.

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