One of the best shows of the annual Leonid meteor shower is expected this weekend, though it won't be a spectacular in North America as it will in Asia.
The Leonids traditionally make an appearance in the pre-dawn sky this time of year as earth passes through the trail of the Comet Tempel-Tuttle, which visits our solar system once every 33 years. The bits of comet burn up as they enter the earth's atmosphere, giving them the appearance of "shooting stars."
Like most meteor showers, they get their name from the constellation from which they appear to emanate -- Leo the lion in this case.
NASA officials say they expect the meteors to dazzle thanks to a tiny sliver of a crescent moon in the sky this weekend, just a few days past the new moon.
"We're predicting 20-30 meteors per hour over the Americas, and as many as 200-300 per hour over Asia," Bill Cooke, of the Meteoroid Environment Office at NASA's Marshall Space Flight Center, said in this NASA feature on the shower. "Our forecast is in good accord with independent theoretical work by other astronomers."
Clear to mostly clear skies are in the forecast for the Baltimore area Friday and Saturday nights, keeping the show visible. The meteors are best seen in an open area away from city lights, and they appear all over the sky, so no need to find Leo. The best time to watch is between midnight and dawn.
Sky-watchers at EarthSky.org are predicting a slightly less active show than NASA expects, with 10-15 meteors per hour over the U.S. In some years, the Leonids are capable of "meteor storms", which generate anywhere from 1,000 to 100,000 meteors per hour.