IT SEEMS comet Wild 2 lives up to its tough-guy name, at least in one respect. Turns out it鈥檚 made of a hard, rocky material rather than the fluffy dust typical of comets.
In 2004, NASA鈥檚 Stardust mission swung by Wild 2 to capture particles shed by the object and return them to Earth. Hope Ishii and colleagues at the Lawrence Livermore National Laboratory in California analysed these microscopic fragments and found the comet is much closer to an asteroid in composition ().
It is unlike an asteroid in that it throws off gas and dust as its surface ice evaporates. So Wild 2 should still be classified as a comet, she says, but the new finding 鈥渋s a good indication that there is a continuum鈥�.
Advertisement
Comets and Asteroids 鈥� Learn more about the threat to human civilisation in our .
