August 10, 2010
This is an incredible week for sky watching - and you don’t need a telescope!
The annual Perseid Meteor shower is already beginning. Last night sky watchers were reporting seeing up to 10 meteors per hour. We found this photo on SpaceWeather.com, shot by Pete Glastonbury of Devizes, Wiltshire, UK, last night. This photograph shows a meteor whizzing past planet Jupiter.
The big show, however, is happening on Thursday night, and it is going to be a beauty.
The spectacular sights begin at sundown, when the crescent moon, Venus, Saturn and Mars will all appear together in a tight circle less than 10 degrees in diameter. You will be able to see this with your own eyes (even better if you have binoculars) - just look to the western sky at twilight. 
This diagram will help you identify which is which, or if you have an Android phone, use your Google Sky Map app. Mercury is there, too, but will be too dim to see with the naked eye.
And if that weren’t enough, Thursday night will be the peak night for viewing the annual Perseid meteor shower. And, since there is just a sliver of a moon this year, the sky will be dark for optimum viewing. From 10pm until dawn you can see meteors streaking across the night sky. Look toward Perseus - in the northern sky. The meteors seem to be shooting out of that constellation, which is why astronomers named it the "Perseid" shower.
Kids often ask me why the Perseid meteor shower happens at the same time every year. The answer is simple. Earth takes one full year (precisely 365 days, 6 hours and seven seconds) to orbit the sun. So every August our planet passes through a big debris field created by the Comet Swift-Tuttle. Every 133 years the huge comet passes through our solar system and leaves a messy trail of dust and gravel behind it. When Earth passes through this cloud of space debris, pieces of it hit our atmosphere at about 140,000 mph and disintegrate in flashes of light that we call meteors.
So get outside as the sun sets this week, imagine that you are an astronomer (actually, if you are watching, you are!) and enjoy the sights.
Posted by: Seymour Simon
