11 September 2003

Tuesday, September 9, 2003
NEWS - SCIENCE 07A
By Tom Burns
For The Columbus Dispatch


As Mars continues to brighten our evening sky, it's easy for an old stargazer to get a bit cynical.

Good views of Mars are rare, and we've waited 15 years to see the Red Planet this well. However, some purveyors of popular astronomical knowledge just can't help themselves. Mars, they say, hasn't been this good for 50,000 years -- or is it 60,000?

Of course, that number represents one of those spectacular but meaningless truths that Americans gobble down like french fries. Mars is essentially as close as it was in 1988 or 1971. The real news is that you'll have to wait more than a decade to see it this well again.

People rush to public stargazing sessions expecting to see plumes from Martian volcanoes, but they will be disappointed. Mars looks like a red dot with a white polar cap and green markings on its surface.

The amazing thing is that we can see anything at all.

Don't despair, my brother and sister stargazers. The sky is full of wonders that we can see all the time. One such is the Andromeda Galaxy, or M31, the farthest object that the unaided human eye can see.

Look for it around 10 p.m. in the constellation Andromeda, low in the east-northeast sky. Binoculars will show it as a hazy, cigar-shaped patch. The light you are looking at took 3 million years to travel to your eyeballs. (One light year is 5.9 trillion miles.)

At 150,000 light years across its disc, M31 is a galaxy even larger than our Milky Way. Looking a bit like a child's pinwheel tilted halfway on its side, Andromeda contains more than 300 billion stars in a flattened disc with a bulge in its center.

Because of the way the galaxy is tilted -- at about a 45-degree angle from our vantage -- the closer edge is about 100,000 light years closer than the farther edge. We see the light from the leading edge 100,000 years earlier than the more distant edge.

In essence, M31 is stretched out in space, but it's also stretched out in time.

In a telescope we can distinguish its central bulge, and in larger telescopes even pretend to trace out the spiral arms that arc out from the bulge. But all of that is irrelevant. If you want to see intricate detail in a telescope, go buy a spotting scope and take up bird watching.

The joy in seeing Mars is just seeing it. The joy in gazing at Andromeda is knowing that you are looking at the farthest thing that human eyes can behold.

Tom Burns directs Ohio Wesleyan University's Perkins Observatory in Delaware.

Search This Blog