Billie’s blog – Meandering Through Cetus

This post is for those with a little bit of observing experience and a small to medium sized telescope although some of the objects here are really good binocular objects.

With all the big baubles of the night sky getting all the attention at this time of year, consider taking an evening touring the constellation Cetus – the Whale. Or as I see it, the Vacuum Cleaner. Or for that matter, after finding it, what shape does it suggest to you? That’s the fun part of looking up. And, by the way, that is how the constellations got their names in the first place! It is fun to think about the ancient astronomers, shepherds, nomads, any of the folk resting from their day labor and reclining with face upturned, under the stars. Imagine them asking each other what shape those stars over the stable look like to them. Cetus follows Aquarius and you get the impression those water related constellation names were named by sailors or fishermen, by those living on or close to the sea. Each culture interpreted the shapes to be similar to familiar objects. The romantics among them interjected a story about how that group was placed there.

But back to Cetus. In the forward part of Cetus, three stars form a large V with the bottom star being Diphda. Use the V like an arrow with Diphda as the point and look just a few degrees south to the big handsome galaxy NGC 253 also called the Sculptor Galaxy (we used to call it the Andromeda of the southern sky). This spiral galaxy has a magnitude of about 8 and can be seen well with modest binoculars from a moderately dark location.

Back to the V in Cetus, just a little bit north of the center of the triangle made by the V is a very large planetary nebula NGC 246, sometimes called the Skull Nebula. Although this is a Magnitude 8 object, it is more diffuse and you will likely need a 4-5 inch telescope to see it well unless you are in a very dark observing location. Take your time with this C shaped object and you will be able to pick out the double star in the middle of it. The fainter of the 2 stars is the one that is sending out it’s deathly final gasps and is the source of the glowing shell of gas as it nears its final state of evolution- a white dwarf. That star was very close to the mass of our own star, the Sun, so we can imagine what our sun will do about 4.5 billion years from now. The star’s expansion is blowing gases out into the space around it. The gasses react with the interstellar medium causing them to glow. The star and its nebula are both traveling in the direction of the brightest part of the C. In the less dense sector of the nebula, they say background galaxies can be seen, though I’ve only seen one little edge on galaxy.

Cetus is also home to the Wonderful Star, Mira. Mira has long been admired for the show it puts on over 11 months when it brightens and dims regularly several magnitudes (10.1 at its dimmest to 1.7 at its brightest). The class of Variable Stars tells us a lot about the life of stars. If you are looking for an introduction to Variables, Mira is a great starter. In fact, some people can get lost in looking at nothing but variables, as a true AAVSO fan will tell you (American Association of Variable Star Observers). My nightly routine in my observatory would begin by planning which variables I would log that night.

I owe all those wonderful nights to Janet Mattei, the Director of AAVSO those many years ago, when she stayed with me in Springville, CA . She was delighted to find the landscape very like her native Greece, and at night she showed me how to fall in love with a light curve.

But Cetus also holds 2 of my favorite galaxies M77 and NGC 1055.

North of Mira a few degrees, M77 is a prime example of a Seyfert galaxy, or a galaxy with an intensely active center that is obscured by gas and dust in visible light. At 9.6 magnitude you will need a telescope but worth it since it is one of the largest galaxies in the Messier catalog. It is located  at a distance of 45 million light-years from us.

Moving only 30 minutes north of M77 is the lovely edge on NGC1055. The two galaxies for a triangle with Delta Ceti.

I hope Cetus gets a chance to take you on a worthwhile cruise.

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