Tag: astronomy

An eccentric debris disk circling a nearby star

11:17 am

Eccentric debris disk around star.

Using the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, astronomers have discovered that the debris disk surrounding a star about 60 light years away, discovered in 2006 by the Hubble Space Telescope, is not circular, but instead forms an eccentric ring about the star.

The photo to the right combines the Hubble data (the blue background) and the ALMA data (the orange-yellow ring). The star is the bright spot in the ring, not in its center but at one of the ellipse’s two foci.

This level of eccentricity, MacGregor said, makes HD 53143 the most eccentric debris disk observed to date, being twice as eccentric as the Fomalhaut debris disk, which MacGregor fully imaged at millimeter wavelengths using ALMA in 2017. “So far, we have not found many disks with a significant eccentricity. In general, we don’t expect disks to be very eccentric unless something, like a planet, is sculpting them and forcing them to be eccentric. Without that force, orbits tend to circularize, like what we see in our own Solar System.”

In other words, there must be at least one hidden planet, maybe more, orbiting the star, its gravity forcing the disk into this shape.

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Chinese scientists detect a fast radio burst that defies the theories

10:08 am

The uncertainty of science: Using their large FAST radio telescope, Chinese scientists revealed this week that they have detected a new fast radio burst (FRB) whose behavior and location does not fit the present tentative theories for explaining these mysterious deep space objects.

The FRB was an exception from the beginning as it flared again and again in observations recorded by the Five-hundred-meter Aperture Spherical radio Telescope (FAST), which nestles among the hills of China’s Guizhou province. The multiple flares put the source among the few percent of FRBs that repeat. But unlike most repeaters, this one doesn’t have any apparent cycle of bursting and quiescence.

“FRB 20190520B is the only persistently repeating fast radio burst known so far, meaning that it has not been seen to turn off,” Li says.

In addition, whatever made the FRB is also emitting a constant buzz of radio waves. Astronomers have found an association with a persistent radio source in only two other FRBs, and for one of these the low-level radio waves seem to come from ongoing star formation in the host galaxy. For FRB 20190520B, though, the radio source is far more compact, and Li’s team thinks the radio waves probably come from the FRB source itself.

The data also suggests the location does not fit the theories, and even suggests that FRBs might not all come from magnetars, as presently proposed.

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Webb gets its first large micrometeoroid impact

9:18 am

In a carefully worded press release this week, NASA revealed that one segment of the primary mirror of the James Webb Space Telescope had been hit by a micrometeoroid.

Between May 23 and 25, NASA’s James Webb Space Telescope sustained an impact to one of its primary mirror segments. After initial assessments, the team found the telescope is still performing at a level that exceeds all mission requirements despite a marginally detectable effect in the data. Thorough analysis and measurements are ongoing. Impacts will continue to occur throughout the entirety of Webb’s lifetime in space; such events were anticipated when building and testing the mirror on the ground.

The reason such events were expected is because — unlike most telescopes (including Hubble) — Webb’s mirrors are not enclosed in a tube for protection. To do so would have made the telescope far too expensive to build or launch.

After describing in great detail all the work done prior to launch to anticipate such hits and deal with them, the press release then mentioned this fact almost as an aside:

This most recent impact was larger than was modeled, and beyond what the team could have tested on the ground.

Localized damage to the primary mirror of any telescope is not unusual. With ground-based telescopes such issues are not infrequent and easily worked around. The same applies to Webb. The engineers will calculate how to calibrate this particular segment to minimize distortion from the impact.

However, that the telescope experienced a hit larger than ever modeled, so soon after launch, suggests that those models were wrong, and that larger and more frequent hits can be expected. If so, this could be very worrisome, as over the long run it could shorten the telescope’s life in space significantly.

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Russia to take control of German telescope on space orbiter

9:12 am

Dmitry Rogozin, the head of Roscosmos, revealed today that he has issued orders for the scientists running the Spektr-RG telescope to figure out how to take over operations of the German instrument on the telescope.

“I gave instructions to start work on restoring the operation of the German telescope in the Spektr-RG system so it works together with the Russian telescope,” he said in an interview with the Rossiya-24 TV channel.

The head of Roscosmos said the decision was necessary for research. “They – the people that made the decision [to shut down the telescope] don’t have a moral right to halt this research for humankind just because their pro-fascist views are close to our enemies,” he said.

The Europeans had shut down operations when it broke off all of its space partnerships with Russia, following the Ukraine invasion and the decision of Russia to confiscate 36 OneWeb satellites rather than launch them as it was paid to do.

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Astronomers used Japanese weather satellite to monitor the dimming of Betelgeuse

10:19 am

Belelgeuse as seen by weather satellite
From Figure 1 of the paper. Click for full image and caption.

In a paper published on May 30th, astronomers described how they used the Japanese weather satellite Himawari-8 to monitor the dimming of Betelgeuse that occurred in 2019 and 2020.

“We saw a tweet stating that the moon was in its images,” Daisuke Taniguchi, a Ph.D. student in astronomy at the University of Tokyo and first author of the paper, told Space.com. “I chatted with [third author] Shinsuke Uno on the usage of meteorological satellites for astronomy, found Betelgeuse is in the field of view of Himawari-8 and realized that maybe the Great Dimming of Betelgeuse could be investigated.”

Himawari-8 has been positioned 22,236 miles (35,786 kilometers) above Earth’s equator since 2015 to study weather and natural disasters (including the eruption of the Hunga Tonga-Hunga Haʻapai volcano on Jan. 15). Although the satellite is up there to image Earth every 10 minutes, the edges of its images include stars.

Taniguchi and his colleagues were able to see Betelgeuse in images taken throughout Himawari-8’s lifetime and measured its brightness roughly every 1.7 days between January 2017 and June 2021.

The scientists were lucky that the star’s unexpected dimming happened to occur during this time period. The image above is Figure 1 from their paper (which you can read here).

They note that their observations appeared to confirm the theory that the dimming was caused by a dust cloud crossing in front of the star, not the theory that it was caused by a dark spot on the star’s surface. Moreover, their data suggests that dust was relatively close to the star, and could even been created by a burst from the star.

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Webb to release first science images July 12th

9:41 am

The science team for the James Webb Space Telescope announced today that the first infrared science images from the telescope will be released on July 12, 2022.

The first images package of materials will highlight the science themes that inspired the mission and will be the focus of its work: the early universe, the evolution of galaxies through time, the lifecycle of stars, and other worlds. All of Webb’s commissioning data – the data taken while aligning the telescope and preparing the instruments – will also be made publicly available.

In many ways this first release will likely mirror the first release of images from the Hubble Space Telescope in 1993, after its serious focus problem had been solved. Then, the science team and NASA picked images for the press conference that, to them, would pass what they called the “grandmother test,” whereby an ordinary person not familiar with space objects would still instantly recognize the object imaged.

The result of that criteria was that some of Hubble’s best ground-breaking first images were not included, such as its first sharp picture of the exploding star Eta Carinae. While the images shown were beautiful, they did not immediately demonstrate what Hubble was going to accomplish. The Eta Carinae picture did however.

Hopefully this time the scientists will be more daring, and have a greater respect for the general public, and include some infrared images that are not familiar to non-scientists. It is such data that is almost always the most exciting.

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Astronomers discover pulsar with slowest rotation rate of any known neutron star

10:05 am

The uncertainty of science: Using the MeerKAT radio telescope in South Africa, astronomers have discovered a pulsar with the slowest rotation rate of any known neutron star, completing each rotation every 76 seconds.

According to the press release:

Neutron stars are extremely dense remnants of supernova explosions of massive stars. Scientists know of about 3,000 of these in our Galaxy. However, the new discovery is unlike anything seen so far. The team think it could belong to the theorised class of ultra-long period magnetars – stars with extremely strong magnetic fields.

From the paper’s abstract:

With a spin period of 75.88 s, a characteristic age of 5.3 Myr and a narrow pulse duty cycle, it is uncertain how its radio emission is generated and challenges our current understanding of how these systems evolve. The radio emission has unique spectro-temporal properties, such as quasi-periodicity and partial nulling, that provide important clues to the emission mechanism. Detecting similar sources is observationally challenging, which implies a larger undetected population. Our discovery establishes the existence of ultra-long-period neutron stars, suggesting a possible connection to the evolution of highly magnetized neutron stars, ultra-long-period magnetars and fast radio bursts.

Essentially, a pulsar with this length rotation was not expected, and its existence throws a wrench into present theories about their formation and evolution. That its existence might provide a link between neutron stars, magnetars, and the as-yet unexplained fast radio bursts, however, is very intriguing.

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Another grand galaxy imaged by Hubble

2:30 pm

NGC 3631
Click for full image.

Cool image time! The photo to the right, reduced to post here, was released today and is one in what has become a steady string of recent and quite spectacular galaxy images produced by scientists using the Hubble Space Telescope. From the caption:

This image from NASA’s Hubble Space Telescope features the Grand Design Spiral, NGC 3631, located some 53 million light-years away in the direction of the constellation Ursa Major. The “arms” of grand design spirals appear to wind around and into the galaxy’s nucleus.

Close inspection of NGC 3631’s grand spiral arms reveals dark dust lanes and bright star-forming regions along the inner part of the spiral arms. Star formation in spirals is similar to a traffic jam on the interstate. Like cars on the highway, slower moving matter in the spiral’s disk creates a bottleneck, concentrating star-forming gas and dust along the inner part of their spiral arms. This traffic jam of matter can get so dense that it gravitationally collapses, creating new stars (here seen in bright blue-white).

This spiral follows the classic shape of these whirlpool galaxies. The Milky Way, though also a spiral, is now thought to be a barred spiral, whereby the galaxy’s whirlpool shape is distorted by a large straight bar of stars crossing its center.

Scientists also released today a second photo from Hubble of a different spiral galaxy, which you can check out here.

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Astronomers: Shut down satellite companies so we don’t have to adapt!

9:31 am

The Hubble Space Telescope
Space-based astronomy, a concept apparently alien to astronomers

In an article published today in Nature, the astronomy community continued its crybaby complaining of the last three years about the interference posed to their ground-based telescopes by the tens of thousands of small satellites scheduled for launch in the next few years.

These quotes typify the apparent attitude of astronomers:

“This is an unsustainable trajectory,” says Meredith Rawls, an astronomer at the University of Washington in Seattle. “At the moment, our science is fine. But at what point will we miss a discovery?”

…“It’s really quite horrifying,” says Samantha Lawler, an astronomer at the University of Regina in Canada.

…The growing threat of satellite constellations adds to other degradations of the night sky such as light pollution, says Karlie Noon, a PhD candidate in astronomy and an Indigeneous research associate at Australian National University in Canberra. “In the same way that our lands were colonized, our skies are now being colonized,” she says. “And this isn’t just Indigenous people.” She points out that companies have launched satellites without necessarily consulting the scientific community. [emphasis mine]

Oh the horror. Scientists weren’t consulted! The nerve of these companies!

In response, astronomers have decided their only solution is to enlist the UN to shut down these satellite companies.
» Read more

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Scientists: Plow the solar system through a dense-enough interstellar cloud and the heliosphere would no longer protect the Earth

11:20 am

The Earth's orbit outside the heliosphere

The uncertainty of science: Using a computer simulation, scientists have determined that if the solar system had two million years ago passed through one of the known nearby interstellar clouds within the relatively empty Local Bubble of space, it would have shrunk the Sun’s heliosphere enough so that the Earth would no longer be inside it, thus exposing the planet to interstellar space.

The image to the right comes from that simulation, and is figure 1 of the scientist’s paper [pdf]. The red line marks the Earth’s orbit (tilted sideways slightly to make it obvious), the yellow blob the shrunken heliosphere.

From the paper’s abstract:

There is overwhelming geological evidence from 60Fe and 244Pu isotopes that Earth was in direct contact with the ISM [interstellar medium] 2 million years ago, and the local ISM is home to several nearby cold clouds. Here we show, with a state-of the art simulation that incorporate all the current knowledge about the heliosphere that if the solar system passed through a cloud such as Local Leo Cold Cloud, then the heliosphere which protects the solar system from interstellar particles, must have shrunk to a scale smaller than the Earth’s orbit around the Sun (0.22).

Using a magnetohydrodynamic simulation that includes charge exchange between neutral atoms and ions, we show that during the heliosphere shrinkage, Earth was exposed to a neutral hydrogen density of up to 3000cm-3. This could have had drastic effects on Earth’s climate and potentially on human evolution at that time, as suggested by existing data.

This model is just one possible explanation of the presence of 60Fe and 244Pu isotopes on Earth. Another popular hypothesis is that a supernova occurred about 30 light years away, close enough to expose the Earth to interstellar space but not so close as to cause the total extinction of life.

With both theories, the event could also be an explanation for the significant climate changes two million years ago — such as the beginning of the most recent and now-ending ice age (no SUVs required) — as well as major evolutionary changes that occurred at that time among the ancestor species of humanity.

All is uncertain however. The scientists have no evidence the Earth actually entered a local dense cloud two million years ago. All they are doing is postulating that if such a thing happened, the dense cloud could shrink the heliosphere so much the Earth would be exposed to the interstellar medium.

Since we also do not yet have evidence of a specific nearby supernovae event either, neither theory can be favored. In fact, both could have been happened at different times in the past. Or neither.

Hat tip to reader Phil Berardelli, author of Phil’s Favorite 500: Loves of a Moviegoing Lifetime.

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A pair of spiral galaxies

2:02 pm

IC 4271, or AP 40, a pair of active galaxies
Click for full image.

Another cool image to herald in the weekend! The photo to the right, cropped and reduced to post here, was taken by the Hubble Space Telescope and shows a pair of spiral galaxies about 800 million light years away.

The smaller galaxy is superimposed on the larger one, which is a type of active galaxy called a Seyfert galaxy.

Seyfert galaxies are named for astronomer Carl K. Seyfert who, in 1943, published a paper about spiral galaxies with very bright emission lines. Today we know that about 10% of all galaxies may be Seyfert galaxies. They belong to the class of “active galaxies” – galaxies that have supermassive black holes at their centers accreting material, which releases vast amounts of radiation. The active cores of Seyfert galaxies are at their brightest when observed in light outside the visible spectrum. The larger galaxy in this pair is a Type II Seyfert galaxy, which means it is a very bright source of infrared and visible light.

In other words, both of these galaxies emit a lot of radiation in the infrared, radio, and X-rays due to activity taking place at the supermassive black holes believed to be at their cores.

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A giant elliptical galaxy

3:14 pm

A giant elliptical galaxy
Click for full image.

Cool image time! The image to the right, reduced to post here, was taken by the Hubble Space Telescope of the giant elliptical galaxy NGC 474.

Located some 100 million light-years from Earth, NGC 474 spans about 250,000 light-years across – that’s 2.5 times larger than our own Milky Way galaxy! Along with its enormous size, NGC 474 has a series of complex layered shells that surround its spherical-shaped core. The cause of these shells is unknown, but astronomers theorize that they may be the aftereffects of the giant galaxy absorbing one or more smaller galaxies. In the same way a pebble creates ripples on a pond when dropped into the water, the absorbed galaxy creates waves that form the shells.

About 10% of elliptical galaxies have shell structures, but unlike the majority of elliptical galaxies, which are associated with galaxy clusters, shelled ellipticals usually lie in relatively empty space. It may be that they’ve cannibalized their neighbors.

NGC 474 is no exception, also located in a relatively empty region of space.

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First radio image of event horizon of Milky Way’s central black hole

9:31 am

Sagittarius A*
Click for full image.

Using an array of eight radio telescopes worldwide, dubbed the Event Horizon Telescope because its purpose is to study black holes, scientists have obtained the first radio image of the event horizon of Sagittarius A* (pronounced “A-star”), the supermassive black hole at the center of the Milky Way.

The image to the right, reduced to post here, is that photo.

The image is a long-anticipated look at the massive object that sits at the very centre of our galaxy. Scientists had previously seen stars orbiting around something invisible, compact, and very massive at the centre of the Milky Way. This strongly suggested that this object — known as Sagittarius A* (Sgr A*, pronounced “sadge-ay-star”) — is a black hole, and today’s image provides the first direct visual evidence of it.

Although we cannot see the black hole itself, because it is completely dark, glowing gas around it reveals a telltale signature: a dark central region (called a “shadow”) surrounded by a bright ring-like structure. The new view captures light bent by the powerful gravity of the black hole, which is four million times more massive than our Sun.

This is the second supermassive black hole that the Event Horizon array has imaged. In 2019 it captured the central black hole of the galaxy M87, 55 million light years away. Like that first image, much of what we see here is created by computer, since the data from the eight radio telescopes needs to be massaged to create something as smooth and as complete as this.

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NASA decides to end airborne SOFIA telescope operations

10:03 am

According to a joint announcement yesterday from NASA and the German space agency DLR, all operations of the airborne astronomy telescope SOFIA will end as of September ’22.

NASA has been trying to cancel this project for several years, because its capabilities have not justified its expense, about $85 million per year. Congress has repeatedly refused to go along, reinserting funding after NASA tried to delete it. That the astronomy community itself suggested in November that the project be canceled, however, probably means this Congress will likely go along with this most recent announcement.

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Colliding galaxies

1:11 pm

Merging galaxies

The string of amazing galaxy images coming from the Hubble Space Telescope continues. The photo to the right, cropped and reduced to post here, was released today and shows an object dubbed VV-689 that is believed to be two galaxies in the process of colliding and merging.

The angelic image comes from a set of Hubble observations that took a closer look at “Zoo Gems,” interesting galaxies from the Galaxy Zoo citizen science project. This crowdsourced program relies on hundreds of thousands of volunteers to classify galaxies and help astronomers wade through a deluge of data from robotic telescopes. In the process, volunteers discovered a gallery of weird and wonderful galaxy types, some not previously studied.

This image will lay the groundwork for more detailed research. Right now it appears no one has even estimated its distance.

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Astronomers discover new type of stellar explosion

11:31 am

Using data from the orbiting TESS observatory and the ground-based Very Large Telescope (VLT) in Chile, astronomers have detected evidence of a new type of stellar explosion they have dubbed a “micronova.”

The micronova appears to be a smaller version of a nova, which brightens the entire star for a month or so.

A white dwarf in a two-star system can steal material, mostly hydrogen, from its companion star if they are close enough together. As this gas falls onto the very hot surface of the white dwarf star, it triggers the hydrogen atoms to fuse into helium explosively. In novae, these thermonuclear explosions occur over the entire stellar surface. “Such detonations make the entire surface of the white dwarf burn and shine brightly for several weeks,” explains co-author Nathalie Degenaar, an astronomer at the University of Amsterdam, the Netherlands.

Micronovae are similar explosions that are smaller in scale and faster, lasting just several hours. They occur on some white dwarfs with strong magnetic fields, which funnel material towards the star’s magnetic poles. “For the first time, we have now seen that hydrogen fusion can also happen in a localised way. The hydrogen fuel can be contained at the base of the magnetic poles of some white dwarfs, so that fusion only happens at these magnetic poles,” says Paul Groot, an astronomer at Radboud University in the Netherlands and co-author of the study.

What this discover really reveals is that as our astronomical observing technology improves, we can observe a greater variety of stellar phenomenon. Expect astronomers in future years to detect an even wider variety of stellar explosions, most of which have not be detectable up until now because we simply couldn’t see them.

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Hubble looks at a tight cluster of five galaxies

1:33 pm

Hickson Compact Group 40
Click for full image.

Cool image time! The photo to the right, cropped and reduced to post here, was taken by the Hubble Space Telescope to celebrate the telescope’s 32nd year in orbit. This cluster of five galaxies is dubbed Hickson Compact Group 40.

This menagerie includes three spiral-shaped galaxies, an elliptical galaxy, and a lenticular (lens-like) galaxy. Somehow, these different galaxies crossed paths in their evolution to create an exceptionally crowded and eclectic galaxy sampler.

Caught in a leisurely gravitational dance, the whole group is so crowded that it could fit within a region of space that is less than twice the diameter of our Milky Way’s stellar disk.

Though such cozy galaxy groupings can be found in the heart of huge galaxy clusters, these galaxies are notably isolated in their own small patch of the universe, in the direction of the constellation Hydra.

The red streaks in three galaxies is thought to be dust, suggesting that stars are still forming in these galaxies. The vertical galaxy on the right is seen edge on. Note too the tilted ring that appears to surround the galaxy on the left.

As for Hubble’s anniversary, the press release notes that since launch in 1990 the space telescope has made 1.5 million observations covering 50,000 heavenly objects, an archive of data available to anyone to access.

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The spiral galaxy M91

3:38 pm

spiral galaxy M91
Click for full release image.

Cool image time! The image to the right, reduced to post here, was released today by the Space Telescope Science Institute as part of a regular program using the Hubble Space Telescope to photograph galaxies.

This observation is part of an effort to build a treasure trove of astronomical data exploring the connections between young stars and the clouds of cold gas in which they form. To do this, astronomers used Hubble to obtain ultraviolet and visible observations of galaxies already seen at radio wavelengths by the ground-based Atacama Large Millimeter/submillimeter Array.

The galaxy is estimated to be about 55 million light years away, and is thought to have a supermassive black hole at its center with a mass somewhere between 9 and 38 million times the mass of the Sun.

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Webb’s coldest instrument reaches operating temperature

1:32 pm

The engineering team announced today that the mid-infrared instrument on the James Webb Space Telescope has now cooled to its operating temperature of -447 degrees Fahrenheit, less than 7 kelvin degrees above absolute zero.

On April 7, Webb’s Mid-Infrared Instrument (MIRI) – a joint development by NASA and ESA (European Space Agency) – reached its final operating temperature below 7 kelvins (minus 447 degrees Fahrenheit, or minus 266 degrees Celsius).

Along with Webb’s three other instruments, MIRI initially cooled off in the shade of Webb’s tennis-court-size sunshield, dropping to about 90 kelvins (minus 298 F, or minus 183 C). But dropping to less than 7 kelvins required an electrically powered cryocooler. Last week, the team passed a particularly challenging milestone called the “pinch point,” when the instrument goes from 15 kelvins (minus 433 F, or minus 258 C) to 6.4 kelvins (minus 448 F, or minus 267 C).

Before science operations can begin the instruments still need further calibration and testing. Expect the first infrared images sometime in the next month or so.

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Astronomers confirm comet with largest nucleus ever found

9:29 am

Using the Hubble Space Telescope astronomers determined that the nucleus of Comet Bernardinelli-Bernstein (C/2014 UN271) is about 80 miles wide, making it the largest comet on record.

The estimated diameter is approximately 80 miles across, making it larger than the state of Rhode Island. The nucleus is about 50 times larger than found at the heart of most known comets. Its mass is estimated to be a staggering 500 trillion tons, a hundred thousand times greater than the mass of a typical comet found much closer to the Sun.

The behemoth comet, C/2014 UN271 (Bernardinelli-Bernstein) is barreling this way at 22,000 miles per hour from the edge of the solar system. But not to worry. It will never get closer than 1 billion miles away from the Sun, which is slightly farther than the distance of the planet Saturn. And that won’t be until the year 2031.

The previous record holder is comet C/2002 VQ94, with a nucleus estimated to be 60 miles across. It was discovered in 2002 by the Lincoln Near-Earth Asteroid Research (LINEAR) project.

This measurement does have a great deal of uncertainty, as Hubble cannot yet resolve the nucleus, and thus its diameter was determined by computer models based on the size of the comet’s coma, or surrounding atmosphere.

The comet itself has an orbit 3 million years long, which means it has zipped into the inner solar system many many times. The reason its nucleus remains so large is because its orbit never gets that close to the Sun, so its material does not get burned off so much with each perihelion. That it exists suggests there could be many such large comets which never dip close to the Sun.

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