It’s an early show this week
In last week’s Starwatch I urged you to get out in the evening and watch the great winter constellations like Orion the Hunter and his gang of bright shiners on the rise in the Marshall eastern sky. This week I urge to get out in the early morning sky, even as early as one in the morning or at least certainly well before morning twilight. All those great winter constellations will still be out there but by then they’ll be shifted over to the western heavens because of Earth’s rotation. You’ll also be celestially greeted by a nice waning crescent moon rising in the southeastern sky.
I know it may take a little more to climb out of that warm bed of yours but it’s so worth getting past that hurdle this week because not only do we have one of the best meteor showers of the year but two bright planets are in quite a celestial hug!
The annual Leonid meteor shower is building and will peak on Friday and Saturday mornings. All this week though you will see a few more meteors or “shooting stars” than normal, especially in the darker countryside. What makes them attractive this year is that there isn’t much moonlight being cast out by the crescent moon leaving a darker backdrop in the sky for catching those “falling stars.” Away from the city lights you may see over 20 or even 30 meteors an hour.
Annual meteor showers like the Leonids occur when the Earth in its orbit around the sun plows into debris left behind a comet. Comets are more or less “dirty snowballs” of rock and ice that orbit the sun in highly elliptical elongated orbits. When their orbits take them close the sun they partially melt leaving a debris trail made up of generally tiny particles from the size of dust grains to small pebbles, about the size of small marbles. The comet that fuels the Leonid Meteor Shower is called Temple Tuttle. It last came through this part of the solar system in 1998 and won’t return again until 2031. The Earth in its solar orbit is busting into this trail from temple Tuttle at 66,000 mph and at the same time these individual comet debris particles or bullets are whizzing along in their orbit at thousands of miles an hour as well. This means that the debris can crash into our atmosphere at speeds over 150,000 mph!
With that kind of speed individual particles quickly burn up due to tremendous air friction and we see the quick streaks of light decorate the celestial dome. The light we see isn’t because of the combustion of the debris. There’s no way you could see that because these tiny particles are burning up anywhere from 50 to 100 miles high. The streak we see is the glowing column of air being chemically excited by the particle that’s ripping through it. Sometimes you see different colors in these streaks that indicate the kinds of gas in our atmosphere that are being temporarily aroused.
Meteors in a meteor shower are best seen after midnight, because that’s when you’re on the side of the rotating Earth that’s plowing into the comet debris. It’s kind of like driving cross county on a warm summer night. You get more bugs smashed on your front windshield than you do on your rear window. After midnight we’re facing the “front windshield” of the traveling Earth.
This meteor shower is called the Leonids because the meteors seem to emanate from the general direction in the sky where the constellation Leo the Lion is poised. After midnight Leo is hanging in the eastern sky and looks like a backward question mark. That makes Leo the radiant of this meteor shower.
That doesn’t mean that you should restrict your meteor hunting to just that area of the heavens. If you do you’ll miss many of them because the meteors can show up anywhere in the sky. Your know they’re part of the Leonids because their “tails” seem to point back in the general direction of Leo the Lion. The best way to watch for the Leonids or any other meteor shower is to lie back on a lawn chair with blankets sometime after midnight, preferably after 2 or 3 a.m., roll your eyes all around the night sky and see how many meteors you spot in a given hour. It’s a fun group or family activity because you can keep each other company and compare meteor sightings.
To top off the morning stargazing this week the two brightest planets we see from Earth, Jupiter and Venus are having a very close conjunction you’ll love, love, love! They’ll be almost “touching” each other. Just as morning twilight begins around 6 a.m. look for the planets in the very low eastern skies just above the horizon. You can’t miss them as they’ll look like cat’s eyes. In fact tomorrow morning they’ll be in their closest celestial hug, less than a half of a degree apart. That’s less than the width of one of your fingers held at arm’s length. Of course the planets are nowhere near each other physically but in the same line of sight. Venus is about 160 million miles away and Jupiter’s about 595 million miles.
Enjoy the early morning delights!
Mike Lynch is an amateur astronomer and professional broadcast meteorologist for WCCO Radio in Minneapolis/St. Paul and is author of the book, “Stars: a Month by Month Tour of the Constellations,” published by Adventure Publications available at bookstores at http://www.adventurepublications.net.