— The Leonid meteor shower appears to originate in the constellation Leo (Illustration: SkyTonight.com)
On 19 November, Earth's orbit will intersect a debris stream left behind by Comet Tempel-Tuttle in 1932 (Illustration: J Vaubaillon)
Sky watchers in western Europe and Africa, northeastern North America and Brazil may get a brief treat this weekend with the height of the Leonid meteor shower.
The meteors are expected to reach peak intensity around 0445 GMT on Sunday (2345 EST on Saturday). The most intense part of the shower will last only a few hours.
Under dark skies, people may spot about 100 to 150 meteors per hour, making the Leonids one of the best showers this year. But it will pale in comparison to meteor showers from 1998 to 2002, when observers counted thousands of meteors per hour.
The reason for the difference is that every year around this time, the Earth passes through a different trail of debris left behind by Comet 55P/Tempel-Tuttle on its passage through the inner solar system every 33 years. Over time, pressure from sunlight segregates the dust and rocks in these trails into separate groups.
In 1998, Earth encountered a very rocky stream, which led to bright fireballs in the sky. This year, however, Earth will encounter a dustier trail of debris that was shed by the comet in 1932 and that dustiness will translate to fainter meteors.
From Earth's perspective, the meteors appear to originate from the constellation Leo, hence the name Leonids. But the meteors can appear anywhere in the sky, so meteor experts suggest leaning back and taking in as much of the night sky as possible.
There should not be much moonlight to interfere with observing the Leonids this year, so meteor watchers will just have to hope for clear skies over the weekend.