1. What is a Comet?
Comet: A chunk of frozen gases, ice, and rocky debris that orbits the Sun
“dirty snowball”

2. A comet has three main parts:

3. Comet Orbits vs. Planet orbits
long, highly elliptical
sometimes close to the sun; sometimes very far from the sun
Planet orbits:
more circular
distance from sun fairly constant

4. Comet Tails: point AWAY from the sun
The coma forms when the sun’s energy causes the frozen gases to “sublimate.”
The solar “winds” push the coma away to form the tail.

5. Two Main Categories of Comet:
Short-period Comets
Long-period Comets
Orbital periods of < 200 years
from the Kuiper Belt beyond Neptune’s orbit
are the ones usually seen from Earth
Orbital periods > 200 years
from the Oort Cloud on the outskirts of the solar system

7. Comets: leftover debris from the formation of the solar system 4
Comets: leftover debris from the formation of the solar system 4.6 billion years ago!
Scientists want to study comets to learn more about the formation of the solar system.

8. A famous comet: Comet Halley
Edmund Halley predicted its return
orbital period: 76 years
Last seen from Earth
When will it return….?

9. Comet Halley
Actual photograph of the nucleus of Halley’s Comet

10. Comet C/ 2011 L4 PanSTARRS – named for the telescope through which it was discovered in June 2011: Panoramic Survey Telescope and Rapid Response System (or PAN-STARRS), a telescope atop the Haleakala volcano in Hawaii.

11. Will we see it….?

12. When will PanSTARRS return. Maybe never
When will PanSTARRS return? Maybe never! It looks like this comet’s orbit might be parabolic…
If it does return, it might not be for another 100,000 years…

13. Where did it come from? Most likely from the Oort Cloud:

14. Should be visible in late November – maybe even in the daytime!
Comet C/2012 S1 (ISON)
Should be visible in late November – maybe even in the daytime!

15. Speculation: Is this the same comet as the Great Comet of 1680?????

16. http://amazing-space. stsci
1. Make your own virtual comet. 2. Read some comment myths and legends. 3. Test your knowledge with “Comet Tails.”