Deep Impact Spacecraft Flies by Small Comet

A NASA spacecraft sped past a small comet Thursday, beaming pictures back to Earth that gave scientists a rare close-up view of its center. Mission controllers burst into applause upon seeing images from the flyby that revealed a peanut-shaped comet belching jets of poisonous gases. The close encounter occurred 13 million miles from Earth when the Deep Impact craft, hurtling through space, flew within 435 miles of comet Hartley 2. It's only the fifth time that a comet's core has been viewed up close.

Scientists are interested in comets because they're icy leftovers from the formation of the solar system about 4.5 billion years ago. Studying them could provide clues to how Earth and the planets formed and evolved. Thursday's flyby is actually an encore mission for Deep Impact. It set off cosmic fireworks on July 4, 2005, when it fired a copper probe that crashed into comet Tempel 1. The high-speed collision spewed a cloud of debris into space, giving scientists their first peek of the interior.

Best View of Comet Hartley 2 Coming Soon

Comet 103P/Hartley 2 was discovered by Australian astronomer Malcolm Hartley in 1986, who calculated that the object orbits the sun about every 6.5 years. Until now, however, gravitational interactions with Jupiter kept shifting the comet's path, sending it closer to the sun and thus farther from Earth during each subsequent return.

This year comet Hartley 2 is on course to make its closest pass by Earth at a mere 11 million miles on October 20—and a dark, moonless sky in mid-October will help create ideal viewing conditions, astronomers say. "Before mid-October, Northern Hemisphere observers will be able to see the comet nearly all night long in the northeast," said Anthony Cook, an astronomer at the Griffith Observatory in California. "After mid-October it can be seen as early as 11:30 p.m. [local time] but is best just before dawn."