National Geographic News

Dust Stream From Comet Tempel 1

Photograph courtesy NASA, ESA, P. Feldman (Johns Hopkins University) and H. Weaver (Johns Hopkins University Applied Physics Laboratory)

A new jet of dust streams from the icy nucleus of the Tempel 1 comet, caught in this Hubble Space Telescope image. The jet extends about 1,400 miles (2,200 kilometers)—roughly half the distance across the U.S.—in the direction of the sun. Comets frequently show outbursts of activity, but astronomers still don't know exactly why they occur.