The Hubble space telescope sure has seen some strange things in deep space, but this most recent find is possibly one of the strangest. Introducing the six-tailed comet… or is it an asteroid? Or some kind of weird alien sprinkler system in the asteroid belt? 
 
 The object — called P/2013 P5 — was discovered in August by the Pan-STARRS 1 telescope in Hawaii, an observation that baffled astronomers. All they could see was a nondescript fuzzy blob. So, employing the help of Hubble, the space telescope slewed around and observed the mystery object twice in September. What it saw was something just as baffling as what Pan-STARRS astronomers originally described: it was a weird multi-tailed comet-like object. Or so it appeared. 
 
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 Apart from the fact that P5 appears to have jets of gas and dust projecting in all directions — like spokes on a bicycle wheel — between the Sept. 10 and Sept. 23, “the entire structure had swung around,” writes a Hubble science news release. This is all very un-comet-like — and, indeed, un-asteroid-like — behavior. 
 
 “We were literally dumbfounded when we saw it,” said David Jewitt, lead investigator from the University of California at Los Angeles. “Even more amazingly, its tail structures change dramatically in just 13 days as it belches out dust. That also caught us by surprise. It’s hard to believe we’re looking at an asteroid.” 
 
 So what is it? Needless to say, there are theories. 
 
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 The asteroid belt, that is located between the orbits of Mars and Jupiter, is home to a huge population of asteroids. Asteroids are known to be affected by the sun’s radiation — like their cometary cousins, they heat up. But given enough time, asteroids can undergo what is known as the Yarkovsky-O’Keefe-Radzievskii-Paddack (YORP) effect. 
 
 The uneven heating on an asteroid’s surface can cause it to “spin up.” In a nutshell, the YORP effect heats up the sun-facing side of an asteroid, but as the asteroid rotates, it radiates heat into space from the dark side. This heat radiation is carried away by infrared photons that themselves exert a tiny amount of momentum, or recoil, as they depart the asteroid. Over long periods (thousands to millions of years), this radiation acts to speed up an asteroid’s spin. 
 
 But what of P5? Could the YORP effect explain these strange spoke features? 
 
 Jessica Agarwal of the Max Planck Institute for Solar System Research in Lindau, Germany, modeled a spinning asteroid to show the tails may be caused by impulsive dust-ejection events. Basically, we could be witnessing an asteroid that has been “spun up” at such a high rate by the sun that it is starting to lose integrity — centrifugal forces are causing it to eject dusty jets into space. “Given our observations and modelling, we infer that P/2013 P5 might be losing dust as it rotates at high speed,” said Agarwal. “The sun then drags this dust into the distinct tails we’re seeing.” 
 
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 The space rock, which measures up to 240 meters wide, has probably only lost about 100-1000 tons of dust — a tiny fraction of its total mass. Although the spinning jets of dust seems the most likely explanation, follow-up observations are needed to see if the jets are being emitted in a plane, from the asteroid’s equator. 
 
 “In astronomy, where you find one, you eventually find a whole bunch more,” said Jewitt. “This is just an amazing object to us, and almost certainly the first of many more to come.” 
 
 Jewitt’s team has published a paper describing this fascinating object in the Nov. 7 issue of The Astrophysical Journal Letters (doi:10.1088/2041-8205/778/1/L21). 
 
 Image: Left: A Hubble observation of P/2013 P5 exhibiting the spoke-like dusty jets. Right: Diagram showing the spinning asteroid generating the jets. Credits: NASA, ESA, D. Jewitt (University of California, Los Angeles), J. Agarwal (Max Planck Institute for Solar System Research), H. Weaver (Johns Hopkins University Applied Physics Laboratory), M. Mutchler (STScI), and S. Larson (University of Arizona) ||||| Nov. 7, 2013: Astronomers viewing our solar system's asteroid belt with NASA's Hubble Space Telescope have seen for the first time an asteroid with six comet-like tails of dust. Designated P/2013 P5, the asteroid resembles a rotating lawn sprinkler. 
 
 "We were literally dumbfounded when we saw it," said lead investigator David Jewitt of the University of California at Los Angeles. "Even more amazing, its tail structures change dramatically in just 13 days as it belches out dust. That also caught us by surprise. It's hard to believe we’re looking at an asteroid." 
 
 This NASA Hubble Space Telescope set of images reveals a never-before-seen set of six comet-like tails radiating from a body in the asteroid belt, designated P/2013 P5. 
 
 Jewitt leads a team whose research paper appears online in the Nov. 7 issue of the Astrophysical Journal Letters. 
 
 P/2013 P5 has been ejecting dust periodically for at least five months. Astronomers believe it is possible the asteroid's rotation rate increased to the point where its surface started flying apart. They do not believe the tails are the result of an impact with another asteroid because they have not seen a large quantity of dust blasted into space all at once. 
 
 Scientists using the Pan-STARRS survey telescope in Hawaii announced their discovery of the asteroid Aug. 27. P/2013 P5 appeared as an unusually fuzzy-looking object. The multiple tails were discovered when Hubble was used to take a more detailed image Sept. 10. 
 
 When Hubble looked at the asteroid again Sept. 23, its appearance had totally changed. It looked as if the entire structure had swung around. 
 
 "We were completely knocked out," Jewitt said. 
 
 Careful modeling by team member Jessica Agarwal of the Max Planck Institute for Solar System Research in Lindau, Germany, showed that the tails could have been formed by a series of impulsive dust-ejection events. She calculated that dust-ejection events occurred April 15, July 18, July 24, Aug. 8, Aug. 26 and Sept. 4. Radiation pressure from the sun stretched the dust into streamers. 
 
 Radiation pressure could have spun P/2013 P5 up. Jewitt said the spin rate could have increased enough that the asteroid's weak gravity no longer could hold it together. If that happened, dust could slide toward the asteroid's equator, shatter and fall off, and drift into space to make a tail. So far, only about 100 to 1,000 tons of dust, a small fraction of the P/2013 P5's main mass, has been lost. The asteroid's nucleus, which measures 1,400 feet wide, is thousands of times more massive than the observed amount of ejected dust. 
 
 Astronomers will continue observing P/2013 P5 to see whether the dust leaves the asteroid in the equatorial plane. If it does, this would be strong evidence for a rotational breakup. Jewitt's interpretation implies that rotational breakup must be a common phenomenon in the asteroid belt. It might even be the main way small asteroids die. 
 
 "In astronomy, where you find one, you eventually find a whole bunch more," Jewitt said. "This is just an amazing object to us, and almost certainly the first of many more to come." 
 
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 Jewitt said it appears P/2013 P5 is a fragment of a larger asteroid that broke apart in a collision roughly 200 million years ago. There are many collision fragments in orbits similar to P/2013 P5's. Meteorites from these bodies show evidence of having been heated to as much as 1,500 degrees Fahrenheit. This means the asteroid likely is composed of metamorphic rocks and does not hold any ice as a comet does. ||||| Back in 2010, astronomers discovered an asteroid that was breaking apart due to a head-on collision with another asteroid. But now they have seen an asteroid break apart – with no recent collision required. 
 
 Asteroid P/2013 R3 appears to be crumbling apart in space, and astronomers using the Hubble Space Telescope recently saw the asteroid breaking into as many as 10 smaller pieces. The best explanation for the break-up is the Yarkovsky–O’Keefe–Radzievskii–Paddack (YORP) effect, a subtle effect from sunlight that can change the asteroid’s rotation rate and basically cause a rubbly-type asteroid to spin apart. 
 
 “This is a really bizarre thing to observe — we’ve never seen anything like it before,” said co-author Jessica Agarwal of the Max Planck Institute for Solar System Research, Germany. “The break-up could have many different causes, but the Hubble observations are detailed enough that we can actually pinpoint the process responsible.” 
 
 
 
 Astronomers first noticed this asteroid on September 15, 2013 and it appeared as a weird, fuzzy-looking object, as seen by the Catalina and Pan-STARRS sky-survey telescopes. A follow-up observation on Oct. 1 with the W.M. Keck telescope on Hawaii’s Mauna Kea revealed three co-moving bodies embedded in a dusty envelope that is nearly the diameter of Earth. 
 
 Then on October 29, 2013, astronomers used the Hubble Space Telescope to observe the object and saw there were actually 10 embedded objects, each with comet-like dust tails. The four largest rocky fragments are up to 200 meters/yards in radius, about twice the length of a football field. 
 
 The Hubble data showed that the fragments are drifting away from each other at a leisurely pace of 1.6 km/hr (one mile per hour), which would be slower than a strolling human. 
 
 “Seeing this rock fall apart before our eyes is pretty amazing,” said David Jewitt, from UCLA’s Department of Physics and Astronomy, who led the investigation. 
 
 The slowness of the speed at which the pieces are coming apart makes it unlikely that the asteroid is disintegrating because of a collision. That would be instantaneous and violent, with the pieces traveling away from each other at much higher speeds. 
 
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 Jewitt also said the asteroid is not coming unglued due to the pressure of interior ices warming and vaporizing, like comets do as they approach the Sun. The asteroid is too cold for ices to significantly sublimate, and it has presumably maintained its nearly 480 million-km (300 million–mile) distance from the Sun for much of its life. 
 
 Jewitt described the YORP torque effect as like grapes on a stem being gently pulled apart due to centrifugal force of an unusually shaped asteroid as it speeds up in its spin. This effect occurs when light from the Sun is absorbed by a body and then re-emitted as heat. When the shape of the emitting body is not perfectly regular, more heat is emitted from some regions than others. This creates a small imbalance that causes a small but constant torque on the body, which changes its spin rate. This effect has been discussed by scientists for several years but, so far, never reliably observed. 
 
 For the break-up to happen, P/2013 R3 must have a weak, fractured interior, probably as the result of previous but ancient collisions with other asteroids. Most small asteroids, in fact, are thought to have been severely damaged in this way, giving them a “rubble pile” internal structure. P/2013 R3 itself is probably the product of collisional shattering of a bigger body some time in the last billion years. 
 
 With Hubble’s recent discovery of an a different active asteroid spouting six tails (P/2013 P5), astronomers are seeing more circumstantial evidence that the pressure of sunlight may be the primary force that disintegrates small asteroids (less than a mile across) in the Solar System. 
 
 The asteroid’s remnant debris, estimated at weighing in at 200,000 tons, in the future will provide a rich source of meteoroids, Jewitt said. Most will eventually plunge into the sun, but a small fraction of the debris may one day enter the Earth’s atmosphere to blaze across the sky as meteors, he said. 
 
 The discovery is published online March 6 in Astrophysical Journal Letters. A preprint of the paper can be found here. 
 
 Sources: UCLA, Hubble ESA 
 
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 By Nancy Atkinson - 
 
 Nancy Atkinson is currently Universe Today's Contributing Editor. Previously she served as UT's Senior Editor and lead writer, and has worked with Astronomy Cast and 365 Days of Astronomy. Nancy is the author of the new book "Incredible Stories from Space: A Behind-the-Scenes Look at the Missions Changing Our View of the Cosmos." She is also a NASA/JPL Solar System Ambassador. 
 
 Asteroids, Astseroid P/2013 R3, Hubble Space Telescope
– The Hubble telescope has spotted a spectacular, perplexing object in the middle of the Asteroid Belt: a rock with six "comet-like" dust tails streaming behind it. "We were literally dumbfounded when we saw it," David Jewitt, the head of the astronomy team studying the P/2013 P5, said in a NASA release. "Even more amazing, its tail structures change dramatically in just 13 days as it belches out dust. That also caught us by surprise. It's hard to believe we're seeing an asteroid." The team hypothesizes that the sun's radiation set the 260-yard-wide rock spinning—thanks, Discovery explains, to the Yarkovsky-O'Keefe-Radzievskii-Paddack effect—so quickly that it lost structural integrity. Using modeling, one team member calculated six dates when the asteroid likely ejected dust into space. So far, it has likely ejected as much as 1,000 tons of dust into space, but that's still a tiny fraction of its mass. "This is just an amazing object to us, and almost certainly the first of many," Jewitt says. "In astronomy, when you find one, you eventually find a whole bunch more."