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Astronomy Picture of the Day 11-17-02
NASA ^ | 11-17-02 | Robert Nemiroff and Jerry Bonnell

Posted on 11/17/2002 12:03:53 AM PST by petuniasevan

Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2002 November 17
See Explanation.  Clicking on the picture will download
 the highest resolution version available.

Leonids from Leo
Credit: Credit & Copyright: Chen Huang-Ming

Explanation: Is Leo leaking? Leo, the famous sky constellation visible on the left of the above all-sky photograph, appears to be the source of all the meteors seen in last year's Leonids Meteor Shower. That Leonids point back to Leo is not a surprise - it is the reason that this November meteor shower is called the Leonids. Sand-sized debris expelled from Comet Tempel-Tuttle follows a well-defined orbit about our Sun, and the part of the orbit that approaches Earth is superposed in front of the constellation Leo. Therefore, when Earth crosses this orbit, the radiant point of falling debris appears in Leo. Over 100 bright meteors can be seen in the above half-hour exposure. The intensity of the Leonid Meteor Shower in 2002 is uncertain but may approach one per second for some locations on November 18 and 19.

TOPICS: Astronomy; Astronomy Picture of the Day; Science
KEYWORDS: astronomy; comet; debris; exposure; image; leo; leonids; meteor; photography; sandgrain; shower; sky; storm; templetuttle
Astronomy Fun Fact:

Why do we see meteors better after midnight?
Because then the Earth's rotation is TOWARD its direction of revolution (orbit).
We then are facing the "front", so to speak, and plowing into the debris.

Have you noticed that the Leonid Meteor Shower has been a subject of discussion at the APOD 5 times in 2 weeks?

This is a not-to-be-missed event. Check back in the APODs to find a webcam if your weather doesn't cooperate.

So how do we see sand-grain-sized particles burning up in the atmosphere miles up? Speed has a lot to do with it. Leonid meteors are some of the fastest; they can enter our atmosphere at speeds of 160,000 miles an hour. At these speeds, the light emitted from collision with air molecules is quite striking. Color can range from red to white to blue and even green. Watch out for larger meteors - fireballs are a sight to see!

Got camera? Some meteors leave a trail of glowing gas for several minutes!
See the Leonids 2001 Meteor Gallery for amazing photos!

If you have meteor-related questions, this site might have the answers:
American Association of Amateur Astronomers: About Meteors and Meteor Showers. Enjoy!

1 posted on 11/17/2002 12:03:55 AM PST by petuniasevan
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To: MozartLover; Joan912; NovemberCharlie; snowfox; Dawgsquat; viligantcitizen; theDentist; ...

2 posted on 11/17/2002 12:04:50 AM PST by petuniasevan
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To: petuniasevan
Good morning & thank you
3 posted on 11/17/2002 1:18:28 AM PST by firewalk
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To: petuniasevan
4 posted on 11/17/2002 6:42:43 AM PST by Joan912
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To: petuniasevan
speeds of 160,000 miles an hour

That would be of an object travelling in the opposite direction than earth. Earth's speed plus the asteroid's speed plus gravitational effects = 160,000 mph maximum.

5 posted on 11/17/2002 11:15:20 AM PST by RightWhale
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To: RightWhale
Very true. "Head-on collision" is the phrase that comes to mind.

I think I'll be clouded out here in WI. Again!
6 posted on 11/17/2002 4:51:14 PM PST by petuniasevan
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