Our Window on Nature

Vision at night is difficult at best, whether you are watching wildlife or searching the sky for meteor showers. But it always seems you need just a bit more light to check the settings on your camera. Or to find the position of a constellation on your star map.

The problem is that flipping on a flashlight ruins your night vision. It takes about 15 minutes for your eyes to adapt to the dark and see detail, and only a second or so of bright light to undo the process. Fortunately there is a solution.

Dim red light has only a minor effect on our vision at night, so a red flashlight allows you to check what you just wrote in your notebook and still look up to see the animals that have better night vision than we do. And the animals are less disturbed by red light.

I’ve seen advertisements for red flashlights, but a less expensive solution is to cover a light source with red cellophane or plastic. When I couldn’t find any locally, I bought a transparent reddish-pink file folder at a stationary store. Two layers did the trick. Enough light to see, but not enough to ruin my night vision.

What more could you ask? Warm summer weather — a new moon (the darkest night) — and one of the most consistent meteor showers of the year. If you’re willing to give up a little sleep, this weekend should be a wonderful show.

On the night of August 12th and the morning of August 13th the Perseid meteor shower should reach its maximum, with the potential of over a meteor a minute. The display occurs as the earth passes through the debris trail left by the Swift-Tuttle comet.

Small meteors enter the earth’s atmosphere every day, but only during a meteor shower do enough appear that you can be sure of seeing them. We actually entered the edge of the Swift-Tuttle trail back in mid-July, so the number of shooting stars has been increasing nightly. If you can’t catch the featured event on Sunday night and/or Monday morning, there are still more meteors than usual just before and after that date.

On August 12th (Sunday) the show gets a slow start around 9:00 pm with what are called Earthgrazers. According to Bill Cooke of NASA’s Meteoroid Environment Office these are “long, slow and colorful; they are among the most beautiful of meteors,” but you will probably only see several of them per hour.

The frequency of meteors keeps improving throughout the night, with the most concentrated portion of the shower occurring before dawn on Monday morning. Although some of the brightest meteors will be visible from urban locations, try to get away from city lights. Give your eyes about 20 minutes to adjust to the darkness, and then watch the darkest portion of the sky.

The photograph of the Perseid Meteor Fireball shown above was taken at Joshua Tree National Park by Wally Pacholka in 1999. Winner of both a Time Magazine and a Life Magazine “Picture of the Year” award, Wally has a spectacular web site featuring comet and meteor photography. Check it out at http://www.AstroPics.com/.

Tonight and over the weekend may be a great time for meteor watchers. It’s the middle of the Leonid Meteor shower, and this year the show could be more impressive than usual.

As a comet travels in its circular path, it drops off small particles which, over centuries, may eventually trail through the comet’s entire orbit. When the earth intersects this path you have a meteor shower. We pass through the orbit of the comet Tempel-Tuttle every November.

The picture on the left is of a Leonid fireball, taken from a DC-8 during the 2002 meteor shower. You can’t get quite that good a view from the ground, but some years meteor shows are truly impressive.

There’s almost no moon this weekend, so there won’t be much visual competition. If you can get completely away from city lights you can see twice as many meteors. The best times should be just before midnight. Just remember — dress warm.