Astronomy Picture of the Day

Explanation: Approaching the inner Solar System, comet Hale-Bopp's icy nucleus is heated by sunlight, accelerating its production of dust and gas. Shrouded in the resulting cloud, known as the coma, the cometary nucleus remains hidden from direct view. However, astronomers using a 2.2 metre telescope at the European Southern Observatory in May, were able to detect an enormous jet of dust extending northward (up) from the nuclear region as seen in this false colour image. Dust jets may arise from vents on the surface of the nucleus. Early estimates of the size of Hale-Bopp's nucleus have indicated that it could be as large as 40 kilometres (24 miles) in diameter -- several times larger than comet Halley's. Hale-Bopp's copious dust production bodes well for it becoming a bright naked-eye comet in the spring of 1997.