Comet Leonard photo

This weekend and early this coming week, the morning skies over Butler are definitely worth waking up and bundling up for to enjoy the annual Geminid meteor shower, one of the best in the year. It reaches its peak early Tuesday morning, but it’s also a pretty show this weekend in the predawn hours.

Meteor showers occur when the Earth runs into a debris trail of dust and small pebbles as it orbits around the sun. Most debris trails are left behind by passing comets that wander into our part of the solar system.

The Geminids are unusual because the debris trail was left behind by a messy asteroid dubbed by astronomers as 3200 Phaethon. This asteroid was discovered in 1983 and may have a diameter of around 3 miles. 3200 Phaethon is a real cosmic litterbug!

It has a highly elliptical orbit that swings it by our part of the solar system every year and a half. Each time it passes by, the debris trail is richly refreshed.

All meteor showers are best seen from midnight to morning twilight, especially about two to three hours before that twilight. That’s because our part of the Earth has rotated into the direction of Earth’s orbit and the debris trail. A good analogy is driving on a warm summer evening; you get many more bugs meeting their demise on your front windshield than on your rear window. After midnight we’re facing the “front windshield.”

This year, the Geminids will be especially good because the moon sets by around 3 a.m., leaving us with darker skies. You’ll have ample time to watch for meteors as twilight kicks in.

On Tuesday morning, during the peak of the Geminids, try to get out to the darker countryside if you’re not already living there. You may see well over 50 to 100 meteors an hour. Even if you’re stuck with more lit-up urban skies, it’s possible to see 20 to 30 “shooting stars” an hour.

Some of these meteors are slamming into our atmosphere at over 40 miles a second. These bits of dust and pebbles get incinerated and vaporized anywhere from 40 to 60 miles above our heads. There’s no way you would be able to see the actual combustion of tiny debris that high up.

The light you see results from tiny columns of air becoming temporarily destabilized and excited as the debris slams through it. Electrons from the atoms get bounced away and then quickly return to their stable orbit.

These streaks can often stay visible for a second or two after the meteor passes while the column of air gets its act back together. Meteors can and do sport different colors depending on what kind of gases they run into, how large they are, and how fast they’re moving. In general, the reddish-tinged meteors tend to be slower meteors, and faster meteors are more bluish.

This shower is called the Geminid meteor shower because all of the meteors appear to be coming from the general direction of the constellation Gemini the Twins, which is in the early morning western sky.

By no means should you restrict your viewing to that part of the sky, however, because the meteors will be all over the heavens. I don’t want you to miss any!

The best thing to do is to layer up in clothes, coats and blankets and lie back on a fully reclining lawn chair, rolling your eyes all around and keeping count of how many meteors you see.

Above all, be patient and vigilant. Meteor shower watching is especially fun with a group of people because the more sets of eyes you have scanning the sky, the more meteors you’ll see collectively.

While you’re lying out watching for meteors, think about this: 3200 Phaethon could be a potential killer asteroid and wipe out most life on Earth if it hit us at just the correct angle. It’s not expected to do that in the foreseeable future, but in 2093, it’s going to miss the Earth by less than 2 million miles. Circle that on your calendar. Happy Geminid watching!

Mike Lynch is an amateur astronomer and retired broadcast meteorologist for WCCO Radio in Minneapolis/St. Paul. Contact him at mikewlynch@comcast.net.