Aug 01

August 2007

What’s Up in the Sky August, 2007
By Peter Burkey

This month offers some great observing opportunities, including a meteor shower and a lunar eclipse.

To see the lunar eclipse you will have to get up very early on the morning of August 28. You probably won’t notice any darkening of the Moon’s surface until 5:00 a.m. with totality beginning around 6:00 a.m. As dawn approaches, the moon will set while still engulfed in Earth’s shadow.

On the night of August 12-13 Earth passes through the trail of dust and debris left by Comet Swift-Tuttle during its 130-year trip around the Sun in past centuries. Think of the times you’ve driven through a heavy snow storm and encountered snowflakes whizzing past your windshield. They seem to emanate from a single point in front of you – called the radiant when applied to meteors. Careful observation of the shower shows that the meteors also emanate from a radiant located in the constellation Perseus, hence the name Perseids.

The particles from the comet range in size from sand grains to pebbles and hit the earth’s atmosphere at 37 miles per second. This creates an incandescent trail of hot, glowing air. What you see is this trail, not the tiny meteoroids themselves.

The best way to view a meteor shower is to find a place with a good view of the entire sky far away from the glare of city lights. Bring a lawn chair, bug spray and a sleeping bag or blankets, lie back facing northeast and be patient. The best time to watch is after midnight when you may see as many as 60 to 90 meteors per hour. An added benefit this year is that there will be no moonlight to wash out the dimmer meteors. For more info check out http://stardate.org/nightsky/meteors.

While you’re at it, you may want to notice the constellations to the north, such as the Big and Little Dippers. As the night progresses you will notice that stars in this part of the sky neither rise nor set, but circle around the star in the end of the handle of the Little Dipper. This is Polaris, also known as the North Star because Earth’s axis, when extended into space, points in the direction of this star.

Next month I will talk more about Polaris, one of the most famous stars up in the sky.

This month in history:
August 2: First televised liftoff of lunar module – Apollo 15’s Falcon – 1971
August 5: Neil Armstrong born – 1930
August 10: Magellan spacecraft orbits Venus – 1990
August 18: Helium discovered in the Sun – 1868
August 20: Voyager 2 launched – 1977
August 24: Voyager 2 flies past Neptune – 1989

Here are this month’s viewing highlights:
Planets this month: Mercury visible before sunrise as August begins. Jupiter continues to dominate the southern sky, seen just above the star Antares in Scorpius. Mars high in ESE in predawn hours.

August 5: Last-quarter Moon
August 12: New Moon.
August 12: Perseid meteor shower.
August 20: First quarter Moon.
August 28: Full Moon.