Comets and Asteroids

This month marks several anniversaries of small body encounters and events. Comets and asteroids are considered to be the pieces that were "left over" from the formation of our solar system. But images of these "left-overs" are far from being unappetizing.

Studies of these small bodies could tell us a great deal about the early days of our home solar system. And we have been studying them. Here are some missions to small bodies celebrating July anniversaries:

• Creating space fireworks just in time for the Fourth of July, Deep Impact flew by and sent an impactor into the path of the nucleus of comet Tempel 1 in 2005.
• In July 1994 comet Shoemaker-Levy 9 left its mark on Jupiter when it impacted the giant planet. This was the first observed planetary impact.
• Deep Space 1 passed by the near-Earth asteroid 9669 Braille on 29 July 1999, imaged the asteroid and found it to be 2.2 km at its longest.
• Last year (10 July 2010) Rosetta flew by and imaged asteroid Lutetia.

There are two asteroid events that you can take part in this month. Coming up on 3 July, if you live in Florida up through Montana you will be able to view with a telescope an occultation of a star by asteroid 52 Europa. For more information concerning this event and to participate in a live web chat, click here and here. Also, in just a couple weeks (16 July), the Dawn mission will encounter and orbit asteroid Vesta. Three weeks later for three days in August (5th, 6th and 7th) Vesta will be full and visible for night sky viewing with a telescope. On those days, the Dawn mission is holding and providing resources for "Vesta Fiesta!" events around the nation. Begin planning your own party for some asteroid fun, or if you happen to be in California in August, Bill Nye the Science Guy will be talking at the Planetary Society's Vesta Fiesta. (And even if you are not, you can still watch the talk streamed live.) So make plans and either create or join a fiesta near you.

Check out the tantalizing images below from past and current small body encounters. And get ready to view the Dawn mission's new data when it comes in later this summer. (8 images total)

Gaspra: The Galileo spacecraft captured this view of asteroid 951 Gaspra in 1991. It was the first time a spacecraft made a close flyby of an asteroid. The colors are highly exaggerated to bring out subtle differences in surface properties. Bluish regions represent fresher rock, while reddish regions are composed of regolith materials. Credit: NSSDC Photo Gallery

Fireworks: This breathtaking image of comet Tempel 1 was taken 67 seconds after it obliterated Deep Impact's impactor spacecraft. The image reveals topographic features, including ridges, scalloped edges and possibly impact craters that were formed long ago. Credit: NASA/JPL-Caltech/UMD

Asteroid Eros: This picture of Eros, the first of an asteroid taken from an orbiting spacecraft, is a mosaic of four images obtained by NASA's NEAR mission immediately after the spacecraft's insertion into orbit. Credit: NASA/JPL/JHUAPL

Almost There: NASA's Dawn spacecraft obtained this image on its approach to the protoplanet Vesta, the second-most massive object in the main asteroid belt. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/PSI

Close-Up: ESA's Rosetta mission returned the first close-up images of asteroid 21 Lutetia showing it is most probably a primitive survivor from the violent birth of the solar system. Credit: ESA 2010 MPS for OSIRIS Team MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA

Comet Crash: These images, beginning at lower right, chronicle the results of one collision of the 21 chunks of comet Shoemaker-Levy 9 slamming into Jupiter. The Hubble telescope recorded this spectacular event. Credit: R. Evans, J. Trauger, H. Hammel and the HST Comet Science Team and NASA

Ida and little Dactyl: Scientists found Ida's moon Dactyl -- the first discovered orbiting an asteroid -- when the Galileo spacecraft flew past the asteroid in 1994. Credit: NASA/JPL

I "Heart" Hartley 2: This stunning close-up view of comet Hartley 2 was taken by NASA's EPOXI mission during its flyby of the comet in 2010. Credit: NASA/JPL-Caltech/UMD

• Vesta Fiesta
• Asteroid 52 Europa
• Year or the Solar System's July Topic: "Asteroids: Leftovers from Planet Building"