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Leonid Meteor Shower
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Image above by George Varros NASA |
The Leonids meteor shower will return on November 19th and although it won't produce a meteor storm like last year, it will still be worthwhile to go outside and observe.
The Leonids are so named because they appear to come from the area of sky where the constellation Leo resides. Meteor showers are also associated with a comet, in this case it's comet Tempel-Tuttle, which sweeps through our part of the Solar System every 33 years and then returns out beyond Uranus.
When a comet approaches the Sun it heats up and leaves behind a river of dusty debris in its orbit. When Earth passes through the dust we have a meteor shower. Over time, the dust spreads out and this is why technically the Leonids run from November 14-20. During this entire time, Earth will pick up Tempel-Tuttle dust that's been spreading for millennia.
The Leonids are known to be very fast. This is because the comet, and therefore its debris is moving in the opposite direction as Earth. It's like two cars hitting head on as the Earth plows through the comet debris. The average Leonid slams into the Earth's atmosphere at 160,000 mph. By comparison, a bullet shot from a gun travels at about 2,240 mph.
Most meteors are caused by debris that is smaller than a grain of sand. It seems hard to imagine that such a tiny speck could make such a bright light across our skies but enough energy is released to light a 100 watt light bulb for just over two seconds. A slightly larger meteor, still just 0.003 inches would pack the power of a .22 caliber bullet.
The average fireball, like the ones we saw during the Leonids storm last year are caused by a piece of debris only about 0.035 inches in diameter. That still sounds incredibly small, however it packs the striking power of a small automobile moving at sixty mph!
It is often mistakenly said that friction with air molecules in Earth's atmosphere is what causes a meteor to burn up. It sounds logical, but simply isn't true. As mentioned earlier, the average Leonid meteor is moving at 160,000 mph and that is fast enough to compress the air in front of it, pushing it out of the way like the wake of a boat. The air itself heats up to temperatures that can exceed 3,000 F. It's the heated air that scorches the meteor.
For this year's Leonids, astronomers have detected two times during which meteor activity will peak. These are two areas of debris the Earth will pass through, both on the night of November 19. At 12:23 a.m. EST (see chart for other time zones.) Earth will be passing through a large area of debris and the shower could last as long as 24 hours. A specific denser area of debris has been pinpointed that we will pass through at 2:28 a.m. EST. At this time, the Earth will pass very close to an area of debris that was ejected from the comet in 1533. During the period around 2:38 a.m. We could see anywhere from 50 to over 100 meteors per hour.
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The good news about that night is the Moon will be a slim crescent and so not a problem. The only bad news is that the debris field seems to be very small particles and so the meteors will not be super bright, so the darker your skies the more meteors you will see.
You don't need binoculars or a telescope to watch a meteor shower. If you do happen to have one though, take a look at Jupiter, that bright object just below Leo. If you want to try other nights from the 14-21 your best bet is to go out between midnight and dawn when the Earth is turning into the debris. Happy hunting!
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