Ray Bower, age 12, of Gary, Indiana, for his question:
What is the fuzzy star in the constellation Andromeda?
The constellation we call Andromeda represents a legendary Greek princess. The ancients who made her immortal may have noticed the pale, fuzzy blur near her head. But in their wildest imaginings they never dreamed what it really is. Powerful telescopes were needed to show that it is a distant galaxy of billions of stars.
In this part of the sky there are six constellations named for characters in the Greek legend of Andromeda. Her parents, King Cepheus and Queen Cassiopeia, are circumpolar constellations that circle the North Star all through the year. The other four begin to rise in our skies in the fall. Andromeda is a crooked triangle constellation just south of Cassiopeia. She was sacrificed to a sea monster and chained to a rock to await her doom. The doom is Cetus, the Whale, over in the southeastern sky. But the hero Perseus arrived in the nick of time to save her. His constellation is close behind her in the northeast. Andromeda's head shares a bright star with the Great Square of Pegasus, a constellation that represents the fabulous winged horse that belonged to the hero.
The bright star that links the head of Andromeda to the tail end of Pegasus is named Alpheratz. Near it, if the sky is very clear and your eyes are very sharp, you may see a dim object that looks like a fuzzy star. When you spot it, you are seeing light that has travelled about one and a half million years to reach the earth. Giant telscopes are needed to reveal its true picture. But they must photograph it section by section. When the pieces are assembled, we have a portrait of a stupendous galaxy of more than a hundred billion stars.
This staggering star system is a sister of the Milky Way, the star studded Galaxy that happens to be our own home in the heavens. Our Galaxy is a flattish circle of cartwheeling stars. It has a thick, crowded hub with spiraling arms thinning out toward its rim. From side to side, it measures about 80,000 light years and it is the home of an estimated hundred billion starry suns. Because of its shape, it is classified as a spiral nebula. Andromeda's galaxy is also a spiral nebula. But its estimated width is 127,000 light years. Big sister is much greater than our Milky Way.
The cosmic scope of size and distance are stunning. But photographs of the Andromeda spiral nebula are even more stunning. In a cosmic beauty contest it would be named Miss Universe. Our view is edgeways and we see the vast system as an oval. The center is bright with crowded stars and the spiraling edges are paler. Altogeth¬er, it looks somewhat like a cosmic sized daisy dipping its star studded head in the rain.
Astronomers catalog the great beauty as M 31. Its light, traveling at 186,000 miles per second, takes more than 1,500,000 years to reach us. And each light year equals almost six million years which is 6 plus 12 zeros. On a cosmic scale, the two star studded beauties are next door neighbors.