Cetus the Sea Monster
Whale or monster? Benign plankton-eating creature or terrifying colossus, a hybrid with gaping jaws and the powerful scaly coils of a sea serpent? This is the constellation Cetus. The monster fell to the hero Perseus, but the stars and deep sky objects are impressive.

http://www.bellaonline.com/articles/art178756.asp

This is the fourth part of my series on the constellations on the myth of Perseus and Andromeda. I still haven't done Perseuse, but there are links at the end of this article to the constellations of Cepheus (the king), Cassiopeia (his queen) and Andromeda (their daughter).

*Happy Birthday, Edwin Hubble (1889-1953)*

On November 20, 1889 Edwin Hubble was born in Marshfield, Missouri. He made two major contributions to modern cosmology. The first used Henrietta Leavitt's relationship between the luminosity and the period of Cepheid variable stars. From this he was able to calculate a distance to such a star in M31, the Andromeda nebula. There was a great debate in astronomy at the time about whether nebulae were actually distant galaxies or objects within the Milky Way. Hubble's calculation showed that M31 was much too far away to be in the Milky Way and must be a separate galaxy.

Hubble's second contribution made use of his data and that of Vesto Slipher and Milton Humason to study the redshifts of galaxies. Galaxies that are redshifted are moving away from us. From his work he determined that the universe was expanding.

You can find out more about Henrietta Leavitt and her ground-breaking work at: http://www.bellaonline.com/articles/art29166.asp

*ESO calendar*

The European Southern Observatory has a wall calendar for sale for 5 euros. (I couldn't see what the postage would be, as it varies depending on the weight of what you buy and where you are.) The pictures are beautiful. You can also get it as a free PDF for your computer. The links for either of these are on this page: http://www.eso.org/public/shop/product/calendar_cal2013/ It's worth looking at, even if you don't want to keep it.

*Thanksgiving*

I hope my American readers are having a good Thanksgiving holiday weekend, whether or not you celebrated Thanksgiving itself.

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I wish you clear skies.

Mona Evans,
Astronomy Editor

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