Astronomy

What is the closest an asteroid or comet has passed the Sun and survived?

What is the closest an asteroid or comet has passed the Sun and survived?


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After SOHO began watching the Sun from space with its coronagraphs 24/7 it was discovered that there are comets passing very close to the Sun quite regularly, and while some are destroyed, some are seen to emerge and continue on.

From these observations and from all other comet and asteroid observations there should be quite a collection of objects whose orbits take them very close to the Sun.

Is there any way to find out What is the closest an asteroid or comet has passed the Sun and survived?


Here is a GIF I made for this answer also used in this answer. In addition to some comets you can see Venus on its approach to occultation by the Sun in 2016. Seeing the Pleiades so close to the Sun is exciting as well!

These LASCO C3 images from SOHO were downloaded sohodata.nascom.nasa.gov/cgi-bin/data_query. The square frame is about 15.9 degrees wide.


Wikipedia offers some useful info on sungrazers:

As of October 21, 2017, there are 1495 known comets that come within ~12 solar radii (~0.055 AU).[2] This accounts for nearly one third of all comets.[3] Most of these objects vaporize during their close approach, but a comet with a nucleus radius larger than 2-3 km is likely to survive the perihelion passage with a final radius of ~1 km.

https://en.wikipedia.org/wiki/Sungrazing_comet

There's a bit about pyroxenes sublimating off at 7 solar radii, but no mention of whether any such object made it around the sun. Pyroxenes generally melt at around 1000°C. An Iron/Nickel body melting at 1538°C/1455°C might well make it through a 7 solar radii passage.


Identity-crisis comet may really be closest asteroid to the sun

When is a comet not a comet? It’s a question astronomers are asking themselves more and more often. Now it seems one of these supposed ice balls might actually be an asteroid that gets within 8 million kilometres of the sun – a cosmic hair’s breadth.

Traditionally, the two kinds of space rocks are thought to be very different. Comets are loose piles of rock and ice on long, elliptical orbits that heat up and develop a tail of gases as they near the sun. Asteroids, on the other hand, are lumpy bodies of hard rock and metal that mostly orbit the sun at a distance that falls between Mars and Jupiter.

But an increasing number of objects are being discovered that blur the line between comet and asteroid. The latest is comet 322P/SOHO 1, which was discovered in 1999 by the Solar and Heliospheric Observatory, a space telescope that examines the area around the sun. But SOHO’s view is shaded to protect it from intense sunlight and its resolution is comparatively low, meaning it can’t get a good look at 322P during the comet’s closest approach to the sun.

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Now, Matthew Knight of the University of Maryland in College Park and his colleagues have used ground-based telescopes and the Spitzer Space Telescope to take another look. They found that there was no sign of a tail from 322P as it got close to the sun. They also found that its density is at least 1000 kilograms per cubic metre, double that of the famous comet 67P/Churyumov-Gerasimenko.

The readings are a big clue that 322P may actually be an asteroid, says Knight: “We’ve never seen a comet with density like this before.”

If so, that would make it the closest-approaching asteroid to the sun, coming to within about 8 million kilometres of it – or roughly 5 per cent of the distance between Earth and the sun.


Asteroid That Just Passed Earth Was Closest Encounter for a Year

Early this morning, a small asteroid passed "extremely close" to Earth&mdashand an astronomer managed to capture a picture of the object as it approached our planet.

The space rock, dubbed 2020 OY4, made its closest approach to our planet at 5:32 a.m. UTC (1:32 a.m. EDT) on July 28, when it was located "just" 0.00028 astronomical units&mdashor around 26,000 miles&mdashaway from Earth, according to NASA's Center for Near Earth Object Studies (CNEOS.)

This is extremely close in astronomical terms, and just 11 percent of the average distance between the Earth and moon.

In fact, data from the CNEOS&mdashwhich tracks so-called near-Earth objects (NEOs)&mdashsuggests that the close approach of 2020 OY4 was the closest that any NEO will come to our planet for the next year at least, if you measure by the "most-likely close-approach distance."

However, if you measure by the "minimum possible close-approach distance," one small object, dubbed 2018 VP1 may come even closer in November, potentially passing at an incredibly close distance of just over 4,700 miles, according to the CNEOS data.

Astronomer Gianluca Masi&mdashfounder of the Virtual Telescope Project (VTP )&mdashsnapped a photo of 2020 OY4 on July 27 when it was located around 155,000 miles from us or, about two-thirds of the Earth-moon distance.

Using one of the VTP's robotic, remotely-operated telescopes known as "Elena," Masi took a single, 120-second-long exposure, in which the asteroid can be seen in the middle as a tiny, bright white dot.

The numerous white streaks in the image are stars, which appear like trails because Elena was tracking the asteroid as it moved at high speeds&mdasharound 27,700 miles per hour relative to the Earth.

The asteroid, which measures between 2.3 to 5.2 meters (7.5 to 17 feet) across, was only discovered on July 26, 2020 during an astronomical survey conducted by the Mount Lemmon Observatory, which is located at an altitude of around 9,100 feet in the Santa Catalina Mountains northeast of Tucson, Arizona.

Despite 2020 OY4's close approach, there was no chance that the asteroid would end up colliding with Earth. And even if it had, NEOs of this size almost always burn up as they enter the atmosphere, meaning they pose little risk.

2020 OY4 is classified as an NEO, a term that refers to any asteroid or comet whose trajectory takes it within 30 million miles of Earth's orbit.


Huge 750ft asteroid TWICE as big as Statue of Liberty to ‘skim past Earth’ later this month

Asteroid 441987 (2010 NY65) has made the US space agency's ⟪rth Close Approach list' and is set to come near us on June 25.

The space rock could be up to 748ft long.

That's more than twice the size of the Statue of Liberty which stands at 305ft.

It's even almost as tall The Shard, which at 1,020ft is the UK's tallest building.

The asteroid should shoot past Earth in the early hours of the morning on June 25.

It will be at it's closest at around 5am UTC to be precise.

There is no need to panic though as the asteroid should only come within 3.7million miles

However, in the grand scheme of space this isn't a large distance at all, so Nasa has still flagged it as a "close approach".

Any fast moving space object that comes within around 4.65 million miles is considered to be "potentially hazardous" by cautious space organisations.

The huge asteroid will be travelling at a speed of just over 30,000 miles per hour.

That makes it one of the fastest and largest asteroids on Nasa's NEO Earth Close Approaches list.


Closest Asteroid to the Sun Found

Image credit: NASA/JPL
The ongoing search for near-Earth asteroids at Lowell Observatory has yielded another interesting object. Designated 2004 JG6, this asteroid was found in the course of LONEOS (the Lowell Observatory Near-Earth Object Search) on the evening of May 10 by observer Brian Skiff.

“I immediately noticed the unusual motion,” said Skiff, “so it was certain that it was of more than ordinary interest.” He quickly reported it to the Minor Planet Center (MPC) in Cambridge MA, which acts as an international clearinghouse for asteroid and comet discoveries. The MPC then posted it on a Web page for verification by astronomers worldwide. It happened that all the initial follow up observations, however, were obtained by amateur and professional observers in the Southwest US. The additional sky positions measured in the ensuing few days allowed an orbit to be calculated.

The official discovery announcement and preliminary orbit were published by the MPC on May 13. This showed that the object was located between Earth and Venus (presently the very bright “evening star” in the western sky). In addition, 2004 JG6 goes around the Sun in just six months, making it the asteroid with the shortest known orbital period. Ordinary asteroids are located between the orbits of Mars and Jupiter, roughly two to four times farther from the Sun than Earth, taking several years to go around the Sun.

Instead, 2004 JG6 orbits entirely within Earth’s orbit, only the second object so far found to do so. “What makes this asteroid unique is that, on average, it is the second closest solar system object orbiting the Sun,” said Edward Bowell, LONEOS Director. Only planet Mercury orbits closer to the Sun.

As shown in the included diagram, JG6 crosses the orbits of Venus and Mercury, passing less than 30 million miles from the Sun every six months. The approximate average orbital speed of this asteroid is more than 30 km/sec, or 67,000 miles per hour. Depending on their locations, the asteroid may pass as close as 3.5 million miles from Earth and about 2 million miles from planet Mercury. In the coming weeks 2004 JG6 will pass between Earth and the Sun, just inside Earth’s orbit. It will move through the constellations Cancer and Canis Minor low in the western sky at dusk. Because of the near-exact six-month period, the asteroid should be observable again in nearly the same spot in the sky next May, having gone around the Sun twice while Earth will have made only one circuit.

From present estimates, 2004 JG6 is probably between 500 meters and 1 km in diameter. Despite its proximity, the object poses no danger of colliding with Earth.

Asteroids with orbits entirely within the Earth?s orbit have been informally called “Apoheles,” from the Hawaiian word for orbit. Apohele also has Greek roots: “apo” for outside, and “heli” for Sun. Objects orbiting entirely within Earth?s orbit are thought by dynamicist William F. Bottke of Southwest Research Institute and colleagues to comprise just two percent of the total near-Earth object population, making them rare as well as difficult to discover. This is because they stay in the daylight sky almost all of the time. There may exist about 50 Apoheles of comparable size to or larger than 2004 JG6, but many of them are certain to be unobservable from the ground.

The first asteroid found entirely inside Earth?s orbit was 2003 CP20, found just over a year ago by the NASA-funded Lincoln Laboratory Near-Earth Asteroid Research project, which observes near Socorro, New Mexico. Although larger than 2004 JG6, 2003 CP20 is a little more distant from the Sun.

LONEOS is one of five programs funded by NASA to search for asteroids and comets that may approach our planet closely. The NASA program?s current goal is to discover 90 percent of near-Earth asteroids larger than 1 km in diameter by 2008. There are thought to be about 1,100 such asteroids.


Comet and Rosetta Spacecraft Make Closest Approach to the Sun

After more than a year in orbit around a comet, the European Rosetta spacecraft and its icy dance partner are hitting a huge milestone: their closest approach to the sun.

The Rosetta and its target, Comet 67P/Churyumov&ndashGerasimenko, reach perihelion today (Aug. 13), when the comet's 6.5-year orbit brings it within 114.9 million miles (185 million kilometers) of the sun.

Activity is already exploding on Comet 67P. In late July, Rosetta's camera caught a jet eruptingin the space of less than half an hour. And because it takes about a month for the comet to get its warmest, this means that activity is expected to peak in a few short weeks. [See more amazing comet photos by Rosetta]

"The key to the Rosetta mission is that it is there for the long haul. It is there to watch and observe changes in the comet over time, with the same suite of instruments, as opposed to a flyby &mdash or maybe different missions having flybys at different times with different instruments," said Joel Parker, an interdisciplinary scientist on the mission. He is a research astronomer and director at the Southwest Research Institute in San Antonio, Texas.

Rosetta arrived in orbit around Comet 67P on Aug. 6, 2014, nearly 10 years after launching into space. In November of last year, the orbiter's small Philae lander touched down on the comet to study the object's surface.

"This is creating the baselines for all future study of comet activity for us to understand what is going on at the small scale, that cannot be observed from Earth or near-Earth observations," Parker told Space.com.

Among other things, researchers will learn about how the brightness of a comet increases, which could lead to better predictions for amateur astronomers, he said. Researchers will also look at how the composition of the comet's emissions (dust and gas) change, which will provide clues about what the early universe looked like.

How the solar system was
Comets such as 67P are considered chunks of what the solar system appeared to be early in its formation, before the planets and moons were formed. Studying comets and asteroids therefore helps researchers understand the makeup of the young solar system shortly after its formation 4.5 billion years ago.

Rosetta is the first spacecraft to orbit a comet and also the first to drop a small probe, the Philae comet lander, on a comet's surface. Among other findings, the Rosetta mission revealed that the type of water on the comet is different than that of Earth, meaning that comets like 67P could not have delivered water to this planet. The spacecraft also detected organics, a building block to life on Earth, and possibly across the universe.

There has been some discussion (and dispute) among the Rosetta researchers as to whether the comet's outgassing will change as the object gets closer to the sun, said Paul Weissman, another Rosetta interdisciplinary scientist who recently retired from NASA's Jet Propulsion Laboratory in California.

Solar heating could unveil deeper regions of the comet that were untouched for millions or billions of years, depending on how much bled away when 67P passed by the sun previously.

"This comet has this unusual &hellip ratio" of the constituents of hydrogen in water, specifically the ratio of a rarer type of hydrogen, called deuterium, to hydrogen, Weissman said. "We're curious to see if that changes as it goes around the sun and as it gets more active.

Comet brightness
It is notoriously difficult for even professional astronomers to predict how bright a comet will appear when it swings by Earth. This is because it's difficult to see the nucleus (heart) of the comet, Parker said, so measurements are made from observing the comet or atmosphere. [Surprising Comet Discoveries by Rosetta and Philae (Infographic)]

As Rosetta observes 67P from up close, the spacecraft will see how much gas is coming out, what dust the gas is dragging out and how big the gas particles are, Parker said. Weissman added that these particles could be a centimeter (0.4 inches) across or larger, which is big enough for the comet's imaging instruments to resolve the individual particles and potentially, track their movements.

The team will also be observing how the solar wind, the constant stream of gas from the sun, interacts with the comet's surface and causes changes, Weissman said. The researchers will additionally watch how the coma of the comet - the dusty envelope around its nucleus - flexes when the solar wind hits it.

Rosetta's current mission ends on Sept. 30, 2016, when the mission will be operating at about four astronomical units or AU from Earth. (One astronomical unit is the Earth-sun distance, about 93 million miles or 150 million km.) At that point, the spacecraft will be so far from the sun that it will be difficult for its solar panels to collect the energy required to continue operating, so further work after that is unlikely, Weissman said.


Historic double comet flyby coming Monday and Tuesday: Here’s what you need to know

When does an asteroid become a comet? When it has a tail. These two images, taken by Michael Kelley and Silvia Protopapa confirmed “asteroid” P/2016 BA14 was actually a comet. The comet is at the center of the frame.

Two comets are headed for a historic flyby of Earth this week, and you don’t want to miss them.

The bigger of the two bodies, known as 252P/LINEAR, is about 750 feet in size and surrounded by an emerald green cloud of gas. It is expected to make its closest approach to our planet on March 21 at 5:14 a.m. PDT.

At that time, it will come within 3.3 million miles of Earth, or about 14 times farther from our planet than the moon on March 21.

The next day, at 7:30 a.m. PDT, a second, smaller comet known as P/2016 BA14 will come even closer --flying within 2.2 million miles of our planet or 9.2 times farther from the Earth than the moon.

That will make it the closest comet to fly past Earth since 1770, according to Sky & Telescope, and the second closest comet to zip past Earth in recorded history.

“There are many more asteroids in near-Earth space than comets, which are significantly more rare,” said Michael Kelley, an astronomer at the University of Maryland. “When a comet does come this close to Earth it is something to get excited about, and take advantage of to learn whatever we can.”

It is possible that comet 252P/LINEAR will be visible to the naked eye eventually. It is expected to grow brighter as it flies toward the sun and more gases sublimate out of its nucleus. However, it will be too far south in the sky to be visible in the northern hemisphere at the time of closest approach.

P/2016 BA14 appears to be quite small and may never grow bright enough to be easily spotted without a telescope, experts said.

If you want to see live video of the comets as they zip past Earth online, the astronomy website The Virtual Telescope is planning two live broadcasts on March 21 and 22.

The bigger comet, 252P/LINEAR, was discovered in April 2000, but the smaller comet was only spotted two months ago in late January. Astronomers using the Pan-STARRS telescope in Hawaii originally had it pegged as an asteroid rather than a comet because they could not yet see a tail.

Russian astronomer Denis Denisenko of Moscow State University noticed that little P/2016 BA14 had a remarkably similar orbit to 252P/LINEAR and wondered whether the two bodies might be related. He shared this observation on the Yahoo Comets mailing list where international professional and amateur comet-watchers trade information.

Kelley and his colleague at the University of Maryland, Matthew Knight, saw Denisenko’s post and were intrigued.

March 20, 11:18 p.m.: A previous version of this story incorrectly identified University of Maryland astronomer Matthew Knight as Michael Knight.

“What are the chances of such an unusual comet and a random asteroid having a similar orbit and Earth close approach?” Kelley wrote on his blog in February. “Probably very small! A lot of suspicion was starting to be cast on this so-called asteroid.”

That same month, Kelley and Knight were able to take images of P/2015 BA14 using a 4.3-meter telescope in Arizona. Both observations showed that the small “asteroid” did indeed have a tail. It was a comet after all.

“It was a really exciting moment,” Kelley told The Times. “I study comets all the time, but I never get the chance to discover them. This was the closest I’ve come.”

Now the astronomy community is trying to determine the relationship between the two bodies. It is extremely improbable that two totally independent comets would fly so close to Earth at almost the same time, Kelley said. Although their orbits are not identical, they are close enough to suggest that they may be two pieces of the same comet that broke apart in the recent past.

To find out, astronomers around the world plan to closely observe the two comets with a variety of instruments, including the Hubble Space Telescope and the Goldstone Deep Space network, to see how similar their orbits are and whether their gas clouds have the same spectral fingerprint.

Kelley said a comet might fracture in two for a a number of reasons. It is possible that the larger body began to rotate too fast and needed to shed mass to stay together. It might be that energy from the sun causes the ices in the nucleus to warm up so rapidly in a particular area that pressure builds up and causes an explosion. Or, it could be that the comet got too close to a planet and the planet’s gravity caused it tear apart.

The researchers hope to learn more after the two comets, or possibly two pieces of a single comet, speed by this week.

No matter what they learn, it should be interesting.

Do you love science? I do! Follow me @DeborahNetburn and “like” Los Angeles Times Science & Health on Facebook.


Closest Asteroid To Ever Pass By Earth Without Hitting Us Has Just Been Recorded

An asteroid the size of a car zoomed by Earth this past weekend and it was the closest fly-by without hitting our planet. The asteroid, called ZTF0DxQ or 2020 QG, passed by us on Sunday, August 16 th at an extremely close distance of just 1,830 miles away. This gives it the title as being the closest non-impact asteroid that’s ever been recorded.

What’s even more amazing is that nobody saw it coming and the Palomar Observatory located in San Diego County, California, didn’t detect it until around six hours after it passed by. Paul Chodas, who is the director of NASA’s Center for Near Earth Object Studies, told Business Insider, “The asteroid approached undetected from the direction of the sun,” adding, “We didn’t see it coming.” “[Sunday’s] close approach is [the] closest on record,” he went on to say, “If you discount a few known asteroids that have actually impacted our planet.”

Space objects that travel from the direction of the sun are extremely hard to see so experts have to look for them in the night sky. But NASA is currently working on a space telescope with an infrared camera called the Near-Earth Object Surveillance Mission that would be able to detect asteroids coming from the direction of the sun that could be launched as early as 2025.

The car-sized asteroid (possibly between 10 and 20 feet in diameter) zoomed by us in a massive hurry as it was travelling at a speed of 27,600 miles per hour. Based on its size, it probably wouldn’t have caused any major damage to our planet or the current population as it more than likely would have exploded in our atmosphere, causing a large fireball in the sky. If any part of the asteroid would have crashed down on Earth, they would have been small pieces that wouldn’t have caused any significant harm.


Closest asteroid circling the sun is a new class of objects in the solar system: Astronomers

A team of astronomers has discovered an asteroid that orbits the sun very closely. Most asteroids orbiting the Sun fall into the asteroid belt, which is located beyond Jupiter, at the outer edge of the solar system.

The newly-discovered asteroid, however, has an orbit between Mars and Venus. Dubbed 2020 AV2, the newly-discovered asteroid has an orbit between Mercury and Venus. It has a diameter between one to three kilometers.

Astronomers have described the space rock as an entirely "new class of solar system objects." What with it being so close to the Sun, it has the smallest axis and aphelion of any objects known so far, they added.

The path of asteroid 2020 AV2 around the sun.

NASA's Jet Propulsion Laboratory revealed that the asteroid will make its close approach to the earth on 14 October 2020, when it is expected to be some 11 million km from Earth.

The team of astronomers at Zwicky Transient Facility clarifies that this doesn't yet mean that 2020 AV2 is the closest asteroid to the Sun. Many asteroids make close approaches of the Sun — often, these approaches are brief, and last only a small portion of the asteroid's full orbit.

For instance, Icarus is the asteroid that comes closer to the sun than Mercury once every 13 months. Yet, is spends a very brief period of time in such close range, before its orbit whisks it away again. Last year, a comet was seen making a suicidal plunge right into the Sun, with all the action caught in video by the SOHO observatory.

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Asteroid makes closest flyby of Earth on record at just 1,800 miles – and Nasa didn’t see it coming

AN ASTEROID the size of a car has zipped past Earth in what scientists say is the closest flyby on record.

Nasa has admitted it didn't see the space rock coming ahead of a near-miss on Sunday that took it within 1,830 miles (2,950km) of our planet.

That's more than 130 times closer to Earth than the Moon (230,000 miles), or less than the distance between Los Angeles and New York City (2,400 miles).

"The asteroid approached undetected from the direction of the Sun," Nasa's Dr Paul Chodas told Business Insider. "We didn't see it coming."

The Palomar Observatory in California first detected the rock, now known as 2020 QG, six hours after it flew over the southern Indian Ocean at 5:08am BST (12:08am ET) on August 16.

At between 6 feet (2m) and 18 feet (5.5m) wide – a little larger than the average sedan – the object posed no threat to Earth.

If it had crossed paths with our planet, QG would have burned up harmlessly in the atmosphere.

The flyby has soared into the record books, however, beating the previous holder of 7,800 miles (12,600km) set in 2019, according to Nasa's Jet Propulsion Laboratory.

“It’s really cool to see a small asteroid come by this close, because we can see the Earth’s gravity dramatically bend its trajectory,” said Dr Chodas.

“Our calculations show that this asteroid got turned by 45 degrees or so as it swung by our planet.”

Nasa constantly tracks asteroids and other "near-Earth objects" to watch for those on a collision course with our planet.

The space agency has been tasked with finding 90 per cent of rocks that pose a significant threat to Earth.

Those "killer" asteroids are typically 460 feet across (140m) or bigger and are easy to spot from a distance.

QG's size and speed – roughly 27,000mph (43,000kph) – were calculated using images captured by the Zwicky Transient Facility at Palomar.

What's the difference between an asteroid, meteor and comet?

  • Asteroid: An asteroid is a small rocky body that orbits the Sun. Most are found in the asteroid belt (between Mars and Jupiter) but they can be found anywhere (including in a path that can impact Earth)
  • Meteoroid: When two asteroids hit each other, the small chunks that break off are called meteoroids
  • Meteor: If a meteoroid enters the Earth's atmosphere, it begins to vapourise and then becomes a meteor. On Earth, it'll look like a streak of light in the sky, because the rock is burning up
  • Meteorite: If a meteoroid doesn't vapourise completely and survives the trip through Earth's atmosphere, it can land on the Earth. At that point, it becomes a meteorite
  • Comet: Like asteroids, a comet orbits the Sun. However rather than being made mostly of rock, a comet contains lots of ice and gas, which can result in amazing tails forming behind them (thanks to the ice and dust vapourising)

The telescope constantly takes pictures of the night sky. Asteroids often form streaks across these images, which are then passed on to researchers.

Only a handful of asteroids of this size pass this close to Earth each year, Nasa said, and they're extremely hard to detect.

“It’s quite an accomplishment to find these tiny close-in asteroids in the first place, because they pass by so fast,” Dr Chodas said.

"There’s typically only a short window of a couple of days before or after close approach when this small of an asteroid is close enough to Earth to be bright enough but not so close that it moves too fast in the sky to be detected by a telescope.”