Nov 01

November 2008

What’s Up in the Sky November, 2008
By Peter Burkey

When you think of the night sky, I mean the clear, dark sky that you saw when traveling out west or visiting the Upper Peninsula, you probably remember being amazed by the number of stars. Millions of stars, shining like diamonds against a black velvet background, make a lasting impression on many. That’s probably why humans have been pondering them since earliest times.

Through the ages, many myths and legends were created to make sense of the mysterious lights in the sky. Besides the Greek mythology and constellations with which we are familiar, there exists a myriad of literature about the stars. To the Babylonians, Chinese, Persians, and Native People of North and Central America stars were an integral part of the religion and their understanding of the world.

In grade school we learn that the stars are like the Sun, but far away. The Sun is a star, but close up. And, like our own solar system, stars form out of giant clouds of gas and dust in outer space. Like a hugh cloud that condenses into a layer of rain or snow, stars form out of mainly hydrogen gas that collapses under the force of gravity.

Once a star has formed, its fate is pretty much determined by its mass. Stars like the sun shine because of the energy that is released in the core where hydrogen atoms fuse to form helium. For stars with high mass, the tremendous core temperature and pressure forces the reactions to be faster and the star “burns out” quickly (a few hundred million to a billion years). Low mass stars, on the other hand, live long, slow lives (more than 10 billion years).

In terms of actual brightness, the Sun is more luminous than the vast majority of stars. However, a few stars are extremely luminous, shining as bright as a million Suns and some emit only 5% as much energy as the Sun. This is a much greater range than that of the masses of stars. The most massive stars are only equal to about 100 Suns.

Stars vary greatly in size as well. A neutron star is only a few miles across, the sun is wider than 100 Earths, and if the Red Giant Betelgeuse were located at the center of our solar system, it would extend past the orbit of Mars.

The end stages in a star’s life are also determined by its mass. Giant stars blow up in a supernova explosion leaving behind a neutron star (pulsar) or, for the most massive, a black hole. Sun-like stars eventually shed their outer layers, leaving behind a white dwarf, and lightweights just fade away.
Now you know a little more about those lights we see up in the sky.

This month in history:
Nov. 2: 100 in. telescope at Mt. Wilson Observatory sees first light – 1917
Nov. 7: Mars Global Surveyor is launched – 1996
Nov. 12: Great Leonid Meteor Shower – 1833
Nov. 19: Hayabusa spacecraft makes first liftoff from an asteroid – 2005
Nov. 26: France launches satellite, becoming the third nation to do so – 1965
Nov. 29: Australia is fourth nation to launch a satellite – 1967

Here are this month’s viewing highlights:
Planets this month: Watch after sunset each night as Jupiter and Venus close in on each other as month progresses. Saturn is high up in the southeast before dawn.

Nov. 3: Crescent Moon appears close to Jupiter
Nov. 5: First-quarter Moon
Nov. 13: Full Moon
Nov. 19: Last-quarter Moon
Nov. 27: New Moon
Nov. 30: Crescent Moon close to both Jupiter and Venus; look also on Dec. 1