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Friday, Mar. 27, 2015

Astronomical rivalries and their outcomes

Thursday, September 22, 2011

Nothing like a good story where the young, handsome, hero rescues the pretty girl who is in danger. Such is the story of Perseus and Andromeda, at least in ancient mythology.

We are looking at the Pegasus/Perseus group of constellations currently rising in the east in the early evening. Last week we looked at Pegasus, the Flying Horse and now we will look at his rider, Perseus -- the young, handsome hero -- and Andromeda -- the fair damsel in distress.

We have covered the story of how Andromeda's mother, Cassiopeia, blabbed it all over about how pretty she was. That made the daughters of the sea god, Poseidon, a little unhappy.

In the interest of domestic tranquility he decreed that Andromeda should be sacrificed to the evil sea monster--played in this story by Cetus, the Whale. More about him later.

Perseus happens by while flying on Pegasus and sees said damsel in dire straits and rescues her, slays the evil sea monster and they all live happily ever after. Or, something like that.

Pegasus is rising in the east these almost-autumn evenings and can best be viewed about an hour after sunset. He is the big diamond shaped group of stars we looked at last week.

Andromeda is represented by the two lines of stars extending to the left (north) of the left-most star of the square of Pegasus. That star is named Alpheratz (pronounced ALPHA-ratz) and it is shared by Pegasus and Andromeda.

From your favorite dark-sky place, start at Alpheratz and follow the two lines of stars out, almost like two arms reaching toward her hero, Perseus, which is represented by a group of stars in the shape of a capital letter "A" just rising over the northeastern horizon.

He can best be seen after 8 p.m. MDT.

Perseus is a great object for binoculars. There is a large, wide-spread group of stars in the background when viewing Perseus. Even better, up about halfway between Perseus and Cassiopeia is a super binocular object, the Double Perseus star clusters.

Two large clouds of stars make a very nice sight in binoculars, even better if you have even a small telescope.

OK, now for the good part. Go back to Pegasus, find Alpheratz, and follow the two lines of stars reaching for Perseus out two stars length.

Estimate the distance between the two stars and go up about the same distance and look for a faint, fuzzy, something. In binoculars that faint fuzzy becomes a larger faint fuzzy but more distinct.

You are looking at the Andromeda Galaxy. Another "Island Universe" similar to our own Milky Way. Another group of billions of stars and who knows how many planets.

You are looking about as far as the human eye can see without optical aid, about 2.5 light years, or almost six trillion miles. Ever wonder if there is anyone looking back at you from there?

This is the same Andromeda Galaxy that will possibly crash into our galaxy in some three to five billion years. Great, something else to worry about.

SKY WATCH: New moon on Tuesday, Sept. 27. Autumn starts at 3:05 a.m. MDT on Friday, Sept. 23. The sun crossed the celestial equator heading south. It is bringing spring to our friends in the southern hemisphere but colder days and nights for us as the season turns. Thursday and Friday, Sept. 22 and 23, a very slender crescent moon will pass just below a glowing Mars in the early morning sky. The best view will be between 4 and 5 a.m. MDT.

NEXT WEEK: Cassiopeia and Cepheus, and more astronomical blathering.


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Vernon Whetstone
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