They just released a new version of blogpress on the iTunes store which is supposed to take care of the posting bug. We will find out soon I suppose.
Someone on Facebook asked me about the best location to see a meteor shower. This is a pretty broad question so I'll attempt to answer it.
First you need to know which meteor shower you are looking for. They were asking about the Leonids. It's usually advertised as happening at it's peak at a certain date. Last Wednesday and thursday we had a peak advertised for a meteor shower near Leo. The showers are often named after the constellations they are going to appear to be coming out of. This means streams of meteors will appear to be coming out of a certain area of the sky near a constellation. You need to know where the constellation is and where it will be in the sky when your looking. So you can focus on the area where the constellation is.
Leo rises and is in the east at about midnight. It's only about 40 degrees up at 3am. So you'd want to look east and up. This would be the quick answer. And you'll want to be out at 3am or even later in the morning when the constellation rises higher in the sky.
If your looking at the constellation and the shower when it's really low in the east then your probably not going to see much, because it's too low and also looking at the shower earlier in the evening will result in your seeing far fewer meteors. The reason for this is the earth rotates in such a way the it's moving away from the path a piece of rock or particle would need to take to burn up in the atmosphere before midnight. Before midnight a meteor would have to catch up to the earth to hit the atmosphere as the earth is moving around the sun in it's revolution around the sun. After midnight the nighttime side of the earth is starting to turn toward the path of revolution (not rotation) which the earth is traveling. So after midnight we are traveling into the path of space particles and they will fly into the earth not only from their motion, but the earth is flying into them. Think of the earth like a car traveling down the street crushing bugs on the windshield. How often do bugs hit the rear window of the car when your driving verses the front. Of course bugs can only hit the back window if your car is traveling at a speed slower than the bug is flying, which is unlikely. Most meteors travel faster than bugs, but they still have to catch up with the viewers position before midnight to enter the night sky. So they need to be travelling faster than earth and catch up to the earth before midnight. This is unlikely, so fewer meteors can be seen before midnight. After midnight we start seeing bugs in the eastern side of the sky which is the front of our imaginary earth car, hitting meteor particles like bugs on the front of a windshield.
The earth is traveling at about 66,400 miles an hour around the sun. So a meteor particle would have to travel faster than this or be caught up in the gravity of the earth and be sucked back into the backside of the earths path to appear before midnight in the sky. Most particles are not going to travel this path, it's much easier to plow into the earth like a bug on a windshield of a car traveling at 66000 miles an hour. So there's a lot more meteor action seen by the observer after midnight.
So the question should be when are you going to be looking for the shower and hopefully it's early in the morning hours after midnight. Once you kow the time, figure out where the constellation is. There are other meteors and these will appear anywhere in the sky. Meteors for the most part come from dust trails from comets. So they are left over clouds of particles from comets, left by comets. They are sitting in some dispersal path or trail around the sun and the earth travels through that path every year as it approaches the path as the earth revolves around the sun. Since we are in the same relative position to the sun and the stars each year, we see the particles coming from the same general area of the sky each year.
Okay now that I've covered some of the basics, what's the best place to view a shower from. Specifically the Leonids. They are about 60 degrees above the eastern horizon at 5:30am. So you want to look east and have a good view of the eastern sky with a nice dark view hopefully. They are about 40 degrees higher than Saturn. There's another more obscure shower nearby, so you may see meteors from a different shower as well. If you don't know where Leo is in the sky you might see other metoers and think they are from the same shower.
Thursday was the peak of the shower and the sky conditions were not very good out. We've had a lot of cloudy weather. You can still see some near the peak of the shower near Leo, just fewer meteors per hour.
A big field is better with less stuff on the horizon. This means someplace where you can see more of the sky. The darker the site the better. This of course brings into question other issues and how to watch meteor showers. Sometimes astronomers have meteor shower parties. Which is just a group of people sitting in lounge chairs or laying down perhaps on blankets, etc. Reclined and looking for meteors in the area of the sky where a shower is expected.
A shower is a shower but now a shower that you might expect. They have a thing called a rate of meteors expected per hour. The rate might be something like 50 meteors per hour. But that's the maximum rate expected. Your mot likely gonng to see that many. You might see far fewer. The meteors will be short and small or sometimes have a long path. They will rarely be one meteor a minute to most viewers. We call it a shower, but if your expecting to see them shower down like water droplets from a shower head, then you'll be disappointed.
Rarely are the rates so high that you'll be excited. I never looked for meteor shower in the old club, when I was in junior high or high school. The showers were best viewed after midnight and we didn't go to the school outings for astronomy after midnight. We were finished by midnight. You'll see more activity from a dark sky site and it's best to view them naked eye. Meaning without binoculars or telescopes. They travel to fast and are to random to see or track in a telescope, and they are sometimes viewed with very wide angle opera glasses which are 3 power by some astronomers who view an area of the sky where they expect the shower to come from.
In a meteor shower party you might divide up thee sky for different people to watch different sections of the sky and if your more experienced you'll be able to tell if the meteor came from the constellation that the shower is supposed to be coming from. There are meteors coming from other areas of the sky and they are generally labelled based on the location they started from.
Here's a screen capture from star walk on the iPad showing a meteor shower location.
Leo is actually up and to the right of Saturn at five o'clock in the morning. The shower would be 60 degrees above the horizon at 5:30 and you can subtract 15 degrees per hour meaning the shower is 15 degrees lower each hour earlier in the eastern sky.
- Posted using BlogPress from my iPad
No comments:
Post a Comment