New images from the VLT show that one of the two nuclei of Comet LINEAR (C/2001 A2), now about 100 million km from the Earth, has just split into at least two pieces If copyright laws applied to cosmic acts, then Comet 2001 A2 would be in court right now.
First it
broke into two pieces earlier this spring just after a rapid brightening session. Now one of those two chunks has split apart and researchers say there may be many smaller pieces flying through space. If the scenario sounds familiar, it's because this isn't the first comet to break apart in recent months. The disintegration act comes less than a year after another comet, called 1999 S4, broke into several large pieces and countless smaller ones, all in plain view of numerous telescopes. That event led to a bevy of
revealing scientific papers on comet formation that were released just last Thursday. Both of these comets have been popularly called "LINEAR," named after the Massachusetts Institute of Technology's Lincoln Near Earth Asteroid Research telescope, which was used to discover them.
The most recent LINEAR comet, 2001 A2, was discovered just this year on Jan. 3 and presumed initially to be intact. It brightened suddenly and unexpectedly back in March and April. As comets approach the Sun, their nucleus of gas and dust burns off and forms a halo, or coma, that glows with reflected sunlight.
Then on April 30th, researchers at the University of Arizona's Lunar and Planetary Laboratory photographed the comet after its nucleus had
broken into two pieces. When a comet breaks apart, more fresh material is exposed, which likely contributed to the sudden brightening.The latest split
Now the comet is about 62 million miles (100 million kilometers) from Earth, but it is no longer visible from the Northern Hemisphere. On May 14, scientists using a European Southern Observatory telescope in Chile noticed that one of the comet's two fragments appeared to be elongated.
On May 16, last Wednesday, it became clear that the comet had split into three pieces. A
colorful image of the latest breakup was released Friday.Hermann Boehnhardt of the European Southern Observatory works on the team that spotted the three large chunks. He told SPACE.com that the orbit of 2001 A2 is so different from 1999 S4 that the two comets are not likely close relatives in terms of where they were created in the disk of gas and dust that swirled around our Sun when it was born.
Depending on what the comet does in coming months, Boehnhardt said, additional observations might allow researchers to figure out where it formed and why it broke apart.
Drifting apart
When Boehnhardt and his colleagues first spotted the comet in three pieces, roughly 310 miles (500 kilometers) separated the two freshly-split chunks. The distance between this pair and the other piece was about 3,700 miles (6,000 kilometers) on May 14 and increased by about 620 miles (1,000 kilometers) within two days.
No one can yet say how big the pieces are or how large the comet's nucleus was before it broke apart.
The comet moves in an exceedingly elongated orbit around the Sun and it is making perhaps its first return trip to the inner solar system after a long hiatus in the
Oort Cloud, a halo of comets that surrounds the solar system. If it is the comet's first pass, that means it has not been in the main part of the solar system since back when it formed, likely about 4.6 billion years ago when the rest of the solar system developed. Its contents would be pristine, and researchers will be interested to study it and see if it adds to
the long list of discoveries made by observing the other LINEAR comet that broke apart last summer.Where it is, where it's going
Comet 2001 A2 can now be seen with the unaided eye by observers in the Southern Hemisphere as a faint object in the southern constellation of Lepus (The Hare).
It will pass through its perihelion -- the point in its orbit nearest to the Sun -- on May 25, at a distance of about 72 million miles (116 million kilometers). Then it will reappear in Northern Hemisphere skies at the end of June after it swings under the Sun. By then, it might be visible to the naked eye, though that is not certain and its recent further disintegration clouds that possibility.
Hal Weaver, a Johns Hopkins University researcher involved in the recent studies of Comet 1999 S4 that broke up last summer, said it's possible the same fate might await 2001 A2.
"We'll have to keep watching over the next several months," Weaver said. Meanwhile, he's working on a French-led team making plans to observe 2001 A2 with the
Hubble Space Telescope, likely in July.Click here
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