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.

Next Tuesday morning (August 28^th) we’ll get to see the second total lunar eclipse of this year. Early in the morning the moon will begin its passage into the shadow of the earth.

Once a month (actually every 29 ½ days) the sun, earth, and moon line up to bathe our planet in the maximum amount of moonlight, allowing moon-watchers to view all the ridges and craters on the near side of the lunar surface. But it’s only several times a year when the alignment is correct for the moon to actually enter the shadow cast by our planet.

During partial eclipses it looks as though a bite has been taken out of the moon, and that’s the way it will start on Tuesday morning. However, since this will be a total eclipse, the entire moon will pass into the shadow region, and for an hour and thirty-one minutes the sun’s light will be blocked by the earth. But the moon doesn’t actually disappear.

Even without direct light the moon will still be visible. As the sun’s rays pass through the earth’s atmosphere, they are slightly refracted (bent), and depending upon the amount of cloud cover and dust in the air, these curving rays will tint the moon in some shade of copper or red. The color is caused by the same phenomenon that gives us beautiful sunrises and sunsets. But this time the color is picked up overhead by the darkened moon.

An eclipse is one of the best times to study the moon. As the shadow of the earth rushes over the lunar surface, it will help highlight the various moon features. A pair of binoculars will make your view even better, and if you do a bit of preparation you’ll know where to look and what to expect.

You can print out a moon map from Space.com. Just point your computer to http://www.space.com/images/skywatchers_moon_map.gif and send the image to your printer. There is also a beautiful detailed topographic map of the moon, showing the seas, craters, and mountains at http://cseligman.com/text/moons/moonnear.htm.

The best show will be on the west coast, starting at 1:51 a.m. Pacific Daylight Time, with the total eclipse starting about an hour later. Add an hour for each time zone as you move east. Unfortunately on the east coast the sun will rise about half-way through the performance. The entire display will last a little over three and a half hours.

The moon image (with added labels) was taken from the Distant Suns computer program. Distant Suns has both a free and a commercial software program that will display the night sky right on your computer. It’s what I use to help me explore the heavens. Check out their website at http://www.distantsuns.com/.

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/.

You can’t actually see the wind. It’s as invisible as sound waves or thermal energy. Yet wind manifests itself in tangible, sometimes startling ways.

The other day as we walked out on the desert we heard the sound of water swirling down a manhole. Well, that’s what it sounded like. We noticed pebbles tumbling almost at our feet, and bushes trembling and grasses bending — and yet we felt no movement. It was a desert whirlwind, acting upon things we could see.

Clouds speeding across the sky give more evidence of wind, and when we see two levels of clouds traveling in opposing directions we realize that winds aloft can blow from different points of the compass. Other times we watch clouds torn into fragments and strewn across the sky, all done by the wind. (Read the rest …)

This weekend (March 3rd) there will be an eclipse of the moon — at least for those on the East Coast. The total eclipse will last for over an hour. A lunar eclipse occurs when the sun, earth, and moon line up with the earth blocking the sun’s rays from striking the moon.

Unlike a solar eclipse, you need take no special precautions to watch the moon partially disappear on Saturday night. Even a total eclipse is only a partial disappearance because some of the sun’s light will be refracted (bent) by the earth’s atmosphere.

Depending upon the amount of cloud cover and dust in the atmosphere, the moon should take on a reddish or coppery cast during the eclipse. According to the Sky Tonight website

Only in New England, Québec, and the Maritime Provinces does the sky become fully dark before the end of totality. Farther west, the eclipse is nearing its end when the Moon rises …

If you live west of the Rockies, you’ll miss this show.

But all is not lost. This year will have several total eclipses of the moon, and on August 28th those of us in the West will see the display while those in the East miss out.

Since the eclipse will already be in progress as the moon rises, take a few minutes Friday evening to mark the location on the horizon near your home. That way on Saturday evening you’ll be able to view the event without missing the opening act.

The moon image was taken from the Distant Suns computer program. Distant Suns has both a free and a commercial software program that will display the night sky right on your computer. It’s what I use to help me explore the heavens. Check out their website at http://www.distantsuns.com/.