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What Is the Brightest Star in the Constellation Cancer?

Cancer the Crab is an inconspicuous constellation that has nothing closely resembling a bright star. The brightest of this dim collection is a star named Al Tarf, an Arab word meaning "the end." The star marks one of the back legs of the celestial crustacean.

Size
- Al Tarf is a fourth-magnitude star, meaning that on a clear and moonless night it is visible to the naked eye. It is so faint due to how far it is from our solar system. Al Tarf is 290 light years away, meaning that the light someone sees from it actually started out from the star 290 years ago.
Distances
- Al Tarf is a binary star, with an orbiting partner star of a much fainter 14th magnitude that is 65 times further away from Al Tarf than Pluto is from the Sun. This great distance causes astronomers to estimate that it circles Al Tarf just once every 76,000 years.
Considerations
- Al Tarf is actually 660 times more luminous than the Sun. If Al Tarf were where the Sun is, it would extend outwards to as far as 65 percent of Mercury's orbit.
Time Frame
- It takes nearly two entire Earth years for Al Tarf to rotate one time on its axis.
Effects
- Astronomers consider that Al Tarf is a dying star, beginning to fuse the helium within its core into carbon and oxygen.

Astronomy