Thursday, 15 November 2012

Everything you need to know: Leonid meteor shower 2012

A meteor during the peak of the 2009 Leonid meteor shower. Photo via Navicore via Wikimedia Commons.

The famous Leonid meteor shower is nearing its annual peak. Here’s all you need to know to watch the 2012 Leonid shower.

Leonid meteors, viewed from space in 1997. Image via NASA

The image at right shows Leonid meteors striking Earth’s atmosphere and creating shooting stars in Earth’s night sky. The 2012 Leonid meteor shower is happening now, day and night, as our world moves through space, crossing the orbital path of Comet Tempel-Tuttle, the parent comet of the Leonid meteor shower.

All this coming weekend will be good for watching this annual shower. The best viewing is predicted for between midnight and dawn on Saturday, November 17, 2012. Just remember, a meteor shower peak prediction is not an ironclad guarantee. If it’s clear, you might see nearly as many meteors in the predawn darkness on Friday, November 16 or Sunday, November 18. The days before and after that might feature meteors as well, as we pass through the Leonid meteor stream in space.

How many Leonid meteors will you see in 2012? The answer of course depends on when you watch, and the clarity and darkness of your night sky. This shower has been known to produce meteor storms, but no Leonid storm is expected this year. The Leonids are usually a modest shower, with typical rates of about 10 to 15 meteors per hour at the peak, in the darkness before dawn.

The good news this year is that the moon is out of the way for the 2012 Leonid meteor shower. The moon will be a thin crescent, setting shortly behind the sun. The moon’s absence from the night sky is a boon to meter-watchers.

When should you watch for Leonid meteors in 2012? Knowing what time to watch is easy this year. Just remember, typically, the best time to watch this meteor shower is between the hours of midnight and dawn. The peak is expected in the hours between midnight and dawn on November 17. That’s your surest bet for seeing some meteors. But you should watch in the hours and days around the peak as well. Start watching tonight! And watch through early next week, at least.

Where should you watch the meteor shower? We hear lots of reports from people who see meteors from yards, decks, streets and especially highways in and around cities. But the best place to watch a meteor shower is always in the country. Just go far enough from town that glittering stars, the same stars drowned by city lights, begin to pop into view.

City, state and national parks are often great places to watch meteor showers. Try googling the name of your state or city with the words city park, state park or national park. Then, be sure to go to the park early in the day and find a wide open area with a good view of the sky in all directions.

When night falls, you’ll probably be impatient to see meteors. But remember that the shower is best after midnight. Catch a nap in early evening if you can. After midnight, lie back comfortably and watch as best you can in all parts of the sky. Sometimes friends like to watch together, facing different directions. When somebody sees one, they can call out meteor! Then everyone can quickly turn to get a glimpse.

The radiant point for the Leonid meteor shower is near the star Algieba in the constellation Leo the Lion. But you don’t have to identify the radiant to see the meteors, which will appear in all parts of the sky.

Which direction should I look to see the Leonids? Meteors in annual showers are named for the point in our sky from which they appear to radiate. This shower is named for the constellation Leo the Lion, because these meteors radiate outward from the vicinity of stars representing the Lion’s mane.

If you trace the paths of Leonid meteors backward on the sky’s dome, they do seem to stream from the constellation Leo. The point in the sky from which they appear to radiate is called the radiant point. This radiant point is an optical illusion. It’s like standing on railroad tracks and peering off into the distance to see the tracks converge. The illusion of the radiant point is caused by the fact that the meteors – much like the railroad tracks – are moving on parallel paths.

In recent years, people have gotten the mistaken idea that you must know the whereabouts of a meteor shower’s radiant point in order to watch the meteor shower. You don’t need to. The meteors often don’t become visible until they are 30 degrees or so from their radiant point. They are streaking out from the radiant in all directions. Thus the Leonid meteors – like meteors in all annual showers – will appear in all parts of the sky.

Will the Leonids produce a meteor storm in 2012? No. Not this year. Most astronomers say you need more than 1,000 meteors an hour to consider a shower as a storm. That’s a far cry from the 10 to 15 meteors per hour predicted for this year. Still, even one bright meteor can make your night.

The Leonid shower is known for producing meteor storms, though. The parent comet – Tempel-Tuttle – completes a single orbit around the sun about once every 33 years. It releases fresh material every time it enters the inner solar system and approaches the sun. Since the 19th century, skywatchers have watched for Leonid meteor storms about every 33 years, beginning with the meteor storm of 1833, said to produce more than 100,000 meteors an hour. The next great Leonid storms were seen about 33 years later, in 1866 and 1867.

A meteor storm was predicted for 1899, but did not materialize. It wasn’t until 1966 that the next spectacular Leonid storm was seen, this time over the Americas. In 1966, observers in the southwest United States reported seeing 40 to 50 meteors per second (that’s 2,400 to 3,000 meteors per minute!) during a span of 15 minutes on the morning of November 17, 1966

Bottom line: Seeing even one bright meteor can be a thrill. And we have become a world of thrill-seekers. If you want to watch the 2012 Leonid meteor shower, just be sure to give it a chance. Find a dark sky location. Plan to watch between the hours of midnight and dawn. Bring along a blanket or lawn chair and spend at least an hour watching. And enjoy!

EarthSky’s meteor shower guide for 2012


No comments:

Post a Comment