Cancer (Pronounciation:Can-sir, Abbrev:Cnc, Latin:Cancri) is a constellation, one of 88 constellations that the night sky is divided into. The sky is not divided up equally between the constellations. Cancer takes up 505.872 sq. degrees of the night sky which equates to 1.23% of the night sky. The constellation gets its name as it name means The Crab . The constellation is one of the original constellations that was devised by the Ancient Greco-Egyptian astronomer Ptolemy who lived between 90 A.D. and 168 A.D.
Cancer is a member constellation of the Zodiac grouping, a group of 12 star signs that astrologers use to predict someones future based on their date of birth and which constellation appeared when the Sun set. The Zodiac year may be divided up equally between the twelve signs but when they appear in the night sky no longer conforms to the Zodiac calendar. Cancer is an equatorial constellation that can be seen by countries nearest the Equator.
The brightest star in Cancer is Altarf. There are 30 Extrasolar Planets (Exoplanets) in this constellation that are detailed on this site. There is a dedicated page for exoplanets in Cancer. For a list of named stars, that is stars that don't start HD or HIP, please visit Cancer Star List Page.
The number of stars that have been catalogued as part of the Hipparcos Star Catalogue from Cancer is 1186. The number of stars that are of magnitude 6.0 or lower in the constellation is 48. The number of stars in the constellation that make up the outline is 5.
There are 2 deep space objects that were identified by Charles Messier in this constellation. There are no non-Messier deep space objects in this constellation that are covered at present on this site.
The nearest star to Earth is HIP 41824 which is roughly about 36.09 Light Years from the Earth. The nearest star to the Earth with an exoplanet is Copernicus which is about 40.25 Light Years. The furthest star that can be located in the constellation is HIP 44539 which is located about 163081.7 Light Years away from the Sun. The furthest figure is derived from either the 1997 or 2007 Hipparcos star catalogue parallax figure and it has been known to produce distances that are wrong.
The dimmest star that can be seen in Cancer with the naked eye is 5 Cancri. The dim star has an apparent magnitude of 5.99. The dimmest star that a person is able to see with their naked eye is 6.0 magnitude based on the table in the reference. Ref: University of Michigan
The caveat of these stars are that they are catalogued on this site. If you know of a star that is nearer or further then do let me know in the comments and I'll add it to the site. The stars mentioned are from the Hipparcos catalogue or have been added because of their special status.
There are 18 Meteor Showers that occur during the year within this constellation based on information gathered from Adam Mickiewicz University (Poland). The ones listed as the ones I've been able to find a date range for. For others if you have the time, you can visit the AMU site, obtains the SL value then use IMO tables to calculate the date. A lot of the Meteor Showers are weak and you need to do a lot of stargazing to spot them.
|Name||Activity||Peak Activity||Closest Star|
|Delta Cancrids||14-Dec - 14 Fen||17-Jan||Asellus Australis|
|Tau Cancrids||Oct 9-25||Oct 17||Tau Cancri|
|Is a Zodiac Sign||Yes|
|Area||505.872 sq. deg.|
|Percentage of Night Sky||1.23%|
|Site Exoplanet Count||30|
|Meteor Shower Count||18|
|Nearest Star||HIP 41824|
|Nearest Star with Exoplanet(s)||Copernicus|
|Dimmest Star||5 Cancri|
|Furthest Star||HIP 44539|
|Bright Star Count||48|
|Hipparcos Star Count||1186|
|Main Star Count||5|
|Messier Deep Space Object Count||2|
|*Non-Messier Deep Space Object Count||0|
|Bordering / Neighbouring / Surrounding Constellations||Lynx|
*Note: The number of Non-Messier Deep Space Object Count relates to how many are covered on this site not how many there are.
The map was generated using Night Vision, an awesome free application by Brian Simpson.
|Messier 67 - King Cobra Cluster||Open Cluster||2.61-2.93 kly||+11:49||08h 50m 4|
|Praesepe, the Beehive Cluster (M44, NGC2632)||Open Cluster||5770||+19:59||08h 40m 1|
|Max Activity Date||17 Jan|
|Activity Period||14-Dec - 14 Fen|
|Max Activity Date||17 Oct|
|Activity Period||Oct 9-25|