The Leonid Meteor Shower

The Leonid Meteor Shower
Sunday evening, 18^th November 2007

This month, we are lucky to have a good chance to view the yearly Leonid meteor shower. Comet Tempel-Tuttle orbits the Sun once every 33 years, and creates a dusty wake of small particles that spreads out along its orbital path. The Earth passes through the remains every November, and once every 33 years we pass through the thickest portion. Meteors are created when these pebble-size grains strike Earth's atmosphere at high speed (the Leonids will arrive at a blistering 44 miles per second), creating streaks of superheated air along their paths.

Eight years ago the Leonids peppered the skies over Europe and the Middle East with 3,000 meteors per hour (nearly one every second). In 1966, residents of the western USA saw a storm of shooting stars raining down at a rate of 100,000 per hour during the peak. While this year's observations will not equal the 1966 extravaganza, they should offer a good viewing experience, with tens of meteors per hour raining down upon us.

Your task is a simple one: go out Sunday evening and watch the meteor shower! This should be a beautiful event, one which illuminates the true motivation for astronomy. This so important that we have decided to value it as 1 extra credit if you write up your observations as described below.

The meteor shower should become most intense for roughly an hour, starting at 11:00pm and trailing off by 12:30am (it will probably peak at 11:30pm). Allow plenty of time for your eyes to fully dark-adapt before beginning to observe (15 minutes after leaving a well-lit room), and use a dim, red flashlight when outside. The duration of an individual meteor is often less than one second - this requires exceptional concentration and quick reactions on the part of the observer!

Before starting your observations you should look for a dark-sky site, since this will considerably improve the experience (your backyard might be fine). You might want to insure a dark sky by driving a little way out of town to a scenic viewpoint, a campsite, or an empty parking lot. Choose a place where you will not be disturbed by street lamps or lit windows. Consider observing with classmates, as this will be safe and fun. If you have children, please consider letting them watch with you.

Comfort is essential for good observations. You might find the following useful:

warm, loose-fitting clothes

a deck chair, air mattress, sleeping bag or blanket, and a pillow; a ground sheet to protect bedding

food and drinks to consume while taking breaks

Your observing equipment could consist of the following:

a watch (ideally with a faintly lit dial)
a dim red flashlight
a pen and paper, and a clipboard
a camera (try using 800-speed film with 10 minute exposures)

If you wish, record the following data for the meteors that you observe:

Time: Record the time when you see each meteor.
Brightness: Compare the brightness of each meteor with nearby stars. Is it brighter than a few, most, or all of the stars you can see?
Colour: Note the colour of each meteor (white, bluish, reddish).
Wake: If you observe a wake (trail) that persists after the meteor has disappeared, time its duration (in seconds).
Rate: Track the number of meteors that you see per minute / ten minutes (depending on how many fall at once).
Point of Origin: Trace the path of the meteors. See whether you can pinpoint a common origin, with respect to background stars.

Summarize the results of your observations, noting the total number of meteors seen, the peak time and rate of the shower, and other important details (brightest meteor, most impressive colours, longest wake). Record your observing site (location), the ambient light level, whether the Moon obscured the sky, the amount of cloud cover, and the direction in which you saw the most meteors (do they all come from the same constellation?). You might want to include a chart, showing how the number of meteors per unit time increased and decreased over the course of the evening. If you manage to take pictures, please share them with the class! Observing meteors is fun, and I encourage you to try it!