University Lowbrow Astronomers

Constellation of the Month: Cancer: The Crab.

by Mark S Deprest
Printed in Reflections: March, 2001.

The Constellation of Cancer

Cancer, the crab seems to have been put into the sky to help fill in the 12 signs of the Zodiac and to sort of tie these 12 signs to the story of the 12 labors of Hercules.  The Crab played a bit part in the second labor.  Where Hercules is to kill the Hydra, a multi-headed, giant water serpent.  The Hydra lived in the marshes Lerna in Greece.  Now there are a number of different versions to just how Hercules finally managed to overcome the Hydra, which seem to have a rather unique ability to grow two heads back each time our hero would lop off one.  Hercules finally figured out that if he put fire to the wound it would sear and seal it shut, so that new heads could not grow up through the old wound.  The Hydra was also renowned to have an extreme case of halitosis (breath that could kill), possibly caused by all that Greek food and the absence of dental floss.  While the battle raged, Juno sent a large crab to attach Hercules’ flank, possibly the first recorded case of a woman getting one of her friends to pinch the cute guy’s butt.  Hercules quickly disposed of the crab and cut off one its claws which he then used to kill the last remaining head.  Hercules dipped the tips if his arrows into the festering wounds and coated them with the Hydra’s deadly juices, so that even the smallest scratch from one of his arrows would result in death.

Transit at Midnight of Alpha Cancer: February 13th

The constellation is situated from 6 degrees North to 33 degrees North declination and is bordered on the East by Leo at 9 hours and 22 minutes Right Ascension, and to the west by Gemini and Canis Minor at 8 hours Right Ascension.  Most of the stars that make up Cancer are rather faint to the naked eye.  Alpha Cancri; Acubens is a 4.26 magnitude A3 spectral class star.  Beta Cancri; Altarf is a 3.52 mag. K2 spec. star.  Delta Cancri; Asellus Australis is a K0 spectral class star that shines at 3.93 magnitude and Gamma Cancri; Asellus Borealis shines at a meager 4.67 magnitude.  Zeta Cancri; Tegmen is a very nice triple star system where Zeta A is a 4.67 magnitude G0 class star.

Things to Check Out in Cancer:

Multiple Star Systems

Zeta Cancri; STF1196; ADS 6650

Iota Cancri; STF1268; ADS 6988

Phi 2 Cancri; STF1223; ADS 6815

Deep Sky Objects

M44; NGC 2632; Beehive Cluster; Praesepe


M67; NGC 2682; open cluster.


NGC 2775; Caldwell 48; spiral galaxy

Variable Stars

R Cancri; Mira-type


All Images on this page were downloaded from the Sloan Digital Sky Survey.

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This page originally appeared in Reflections of the University Lowbrow Astronomers (the club newsletter).
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