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Proper NameBrahe
DesignationsCopernicus c, Rho1 Cancri c, 55 Cancri c, HD 75732 c
Also sometimes specified as Rho1 Cancri A c, 55 Cancri A c, HD 75732 A c
ClassificationGas Giant
Orbital Period44 days, 10 hours
Mean Distance from Copernicus35.5 million km
0.24 AU
Mass0.16 x Jupiter
DiameterNot known
TemperatureNot known
Parent starCopernicus (Rho1 Cancri, 55 Cancri), yellow dwarf in Cancer
Other planets in this systemGalileo (Copernicus b), gas giant
Harriot (Copernicus f), gas giant
Janssen (Copernicus e), super Earth
Lipperhey (Copernicus d), gas giant

Copernicus (also designated Rho1 Cancri or 55 Cancri) is a relatively Sun-like yellow-orange star in the constellation of Cancer, some forty-one light years from the Solar System. This is a binary system, in which the yellow primary is orbited by a red dwarf, and also notably by a system of five known planets. The primary star and its planets are each named for important figures in the history of astronomy, and one of these is a probable gas giant named for the sixteenth-century Danish astronomer Tycho Brahe.

Imagery provided by Aladin sky atlas

Four of the five planets of the Copernicus system orbit close to their star, within the radius of the Earth's orbit around the Sun, and Brahe is the third of these from its star. The planet has more than fifty times the mass of Earth, which equates to about 0.16 that of Jupiter, making Brahe most likely a rather small gas giant. Brahe's orbit has a semi-major axis of 0.24 AU (placing it closer to Copernicus than Mercury is to the Sun, even though two other Copernican planets follow closer orbits). A 'year' on Brahe - that is, the time taken by the planet to complete a single orbit - would last a little over fourty-four days.


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