Wednesday, August 7, 2013
Good Meteor Shower Starts This Weekend
Whenever small chunks of cosmic dust or dirt hit the Earth's atmosphere at high speed and heat up, they make a flash of light that's visible from the ground. We call these meteors or "shooting stars." When the Earth encounters an organized swarm of cosmic material, we call it a meteor shower.
The Perseids (one of our most reliable meteor showers) is best this year the night and morning of Sunday Aug. 11 to Monday Aug. 12, and the night and morning of Monday Aug. 12 to Tuesday Aug. 13th.
Watching for meteors is easiest for most people’s schedules in the evenings (before midnight). However, the meteor display is generally better after midnight (making night owls and early risers happy.)
The Perseids are better after midnight for two reasons this year:
a. The Earth turns after midnight to face the shower (so that the meteors are coming more directly at us)
b. The crescent Moon will set by then, so its light will not bother meteor shower fans. (On Aug. 11, the Moon sets at 10:32 pm, while on Aug. 12th the Moon sets at 11:10 pm.)
Whenever during those two nights you decide you want to watch, here are Fraknoi’s Friendly Meteor Shower Tips for best viewing:
1. It’s more important to decide WHERE to watch them, than WHEN to watch them. The crucial issue is that meteors are faint, so you need a location where the sky is DARK. That means getting away from city and car lights as much as possible. The darker your site, the more you will see.
2. Of course, if it’s foggy or cloudy, you won’t see a thing. So make sure you get to a place where the sky is not only dark but CLEAR.
3. Don’t use a telescope or binoculars. (Meteor showers are one of the most democratic of sky shows; those of us in the 99% can enjoy them as much as those in the 1%!).) Your eyes are the best tool, because the flash can be anywhere in the sky. So restricting your view to a small part of the sky makes it more likely you will miss many of the meteor flashes.
4. Dress warm for night-time temperatures and be patient. Meteor showers are far more subtle than fireworks. You will need to relax and wait for time to pass. First, it takes a while for your eyes to get adapted to the dark (I recommend at least 15 minutes) and, second, a minute or several minutes might pass without a single flash. Eventually, though, you should see significantly more shooting stars than on a regular night.
5. So (perhaps most important) try to take someone with you with whom you like to spend time in the dark.
The Perseid meteors are cosmic “garbage” (dust and dirt clumps) left over from a regularly returning comet, called Swift-Tuttle (after the two astronomers who first discovered it). When comets get near the Sun, their ice evaporates, leaving behind some of the dirt that was frozen inside them. Since comets are "left-overs" from the early days of our solar system, you can tell yourself that each flash you see is the “last gasp” of cosmic material that formed about 5 billion years ago.
(Our photo, by ESO Photo Ambassador Stéphane Guisard, shows a bright Perseid meteor in 2010 over the grouping called the Very Large Telescope at the European Southern Observatory in Chile.)