Dec. 16, 2011 — -- Take a look at the video that goes with this story. It shows a celestial close call -- a comet, called Comet Lovejoy, appearing to plunge headlong into the sun, but finally missing by only 87,000 miles (about a tenth of the sun's diameter) and emerging from behind it. (Update: Another video, shot from the International Space Station Dec. 22, shows the comet streaking away from the sun.)
Comets are devoured by the sun frequently. They are essentially flying snowballs, clumps of rock, dust and ice hurtling through space, and they are easily vaporized by the sun's fierce heat.
Lovejoy survived -- and it was all captured by the SOHO spacecraft, hovering in solar orbit about a million miles from Earth. SOHO, the Solar and Heliospheric Observatory, was launched by NASA and the European Space Agency in 1995. Its images are shot through different filters, which is why the Comet Lovejoy images appear blue; others are in red, green or gold. The sun itself is blocked by a disc in the camera so that its light will not drown out the outer layers of the solar atmosphere, the violent flares and the passing comets that SOHO watches.
Sun-skimming comets are not unusual, but they are rarely as large as Lovejoy. This one was only discovered on Dec. 2 by an Australian amateur astronomer, Terry Lovejoy. Many comets lurk in the outer reaches of the solar system, diverted sunward by the gravity of other objects they pass.
"This is by far the biggest and brightest one that we've observed in 15 years. In fact, it would appear to be the brightest and biggest one in the last 41 years," said Douglas Biesecker of the Space Weather Prediction Center in Boulder, Colo.
The comet, its head about 150 yards wide, just missed a direct impact and passed behind the sun as seen from Earth. It emerged, as one scientist put it, "still bright, still wagging its tail."
As it got closer to the sun, the tail of the comet stretched about 4.5 million kilometers (2.8 million miles) behind. Scientists expected that even though the comet wasn't actually falling into the sun itself, it would dissipate as its dust and vapor streamed into space.
But early this morning a wispy comet was seen racing away from the sun. SOHO and a second NASA spacecraft, the Solar Dynamics Observatory, caught images of it -- much diminished, but still very much there.
"It's still ridiculously bright," wrote Karl Battams, who runs the Sungrazing Comets website at the U.S. Navy's Office of Naval Research. "It will be back in a few hundred years."