SIMply the Farthest
One of the great thrills for many novice skywatchers is seeing the full glory of the Milky Way for the first time. This hazy band of light is so faint that it's not visible from light-polluted cities - only from dark locations far from city lights.
The Milky Way is the combined glow of millions of stars in the disk of the Milky Way galaxy. Astronomers can see these stars with their telescopes. Most of the stars are so far away, though, that astronomers can't measure their distances.
But that may change in the next decade with a satellite called SIM. It should be able to measure the distance to any star in the band of the Milky Way - and to the brightest stars on the far side of the galaxy.
SIM will compare the positions of stars as it orbits the Sun. The stars will appear to shift back and forth just a little bit. Astronomers use this same technique today with telescopes both on the ground and in space. But they get good measurements only out to about a thousand light-years.
Unlike other space observatories, SIM will have more than one telescope. Scientists will combine the light from these telescopes to see the universe with unprecedented clarity. They expect SIM to measure the distances to stars that are up to 80,000 light-years away - stars on the far edge of the Milky Way.
The Milky Way is in fine view tonight, arcing high across the east at nightfall, and directly overhead around midnight.
Script by Damond Benningfield, Copyright 2005
For more skywatching tips, astronomy news, and much more, read StarDate magazine.
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