Comets and Forces Comet Hyakutake

Comet McNaught, 2005 From Australia…. …and from space (STEREO)

Comets orbit the Sun and are sometimes consumed by it.

Comet cores are mostly ice, rock, and organic compounds. Precise content unknown until the spacecraft Stardust landed on (crashed onto) comet Wild 2.

March 1994, D. Levy and the Shoemakers discover a strange kind of comet. (the lines on the rightmost picture are satellites crossing the field of view)

Comet Shoemaker-Levy 9 had been captured by Jupiter’s gravity, which had also broken the comet up into many pieces. These pieces were in a direct collision course towards its captor. This pic is a combination of two pictures (comet and Jupiter). Notice the moon Io and the shadow it casts.

This is a movie made of the pictures the Voyager spacecraft took as it approached Jupiter.

The fragments collided with Jupiter from July 16 to July 22, 1994, at a speed of approximately 60 kilometers per second. These are pictures of the fireballs produced during some of these impacts.

Jupiter after impacts

The above is a sequence, from bottom right to upper left, of Jupiter shots as comet fragments crashed onto it. To the right is a post-impact shot in UV.

Jupiter seen in the infrared. Note the impact sites and the Red Spot above. Upper right shows Io as well. Why do you think is it so hot? To the right, the view two months later gives evidence of how much the impact sites were heated.

Infrared view of Jupiter, impact points, and fragment K (at tip of arrow) 45 minutes before impact. Other bright points are stars. What was the impact force of these fragments? V i =60 Km/s V f =??? (How was V i =60 Km/s determined?) M=1x10 12 – 1x10 13 g (pick one) Some other forces to compare to: Car crash from 30 mph: ~30,000 – 100,000 N Boxer’s punch (Enzo Maccarinelli): 31,000 N F=ma