January's Star is Rigel

This month’s star is Rigel, the blue-white star marking Orion’s left foot. Rigel is called Beta Orionis by astronomers. To appear as the 7th brightest star in the sky at a distance of 863 light years, Rigel has to be a very large and massive star. Therefore, it’s not surprising to learn that Rigel is 120,000 times brighter, 25 times more massive, and 96 times larger than the sun. If it replaced our sun, the surface of Rigel would engulf poor little Mercury. It would appear some 45 degrees across in our sky and roast Earth’s surface to death.

Like people, stars this massive don’t live long. It appears Rigel is only 8 million years old and it’s already used up its original supply of hydrogen. The star is now consuming its supply of helium ash. In star years, Rigel will not last much longer. And when it does go, it will explode as a supernova and send the heavy metals it has generated over its short life across this region of the galaxy. As a result, future stars will form with more elements like carbon, oxygen, iron, and gold.  

The star’s name comes from the Arabic word for foot (in Arabic, the star is called the foot of the great one). The oldest reference to its current name goes back to the 13th century.

Rigel can be seen in the low southeast before the sky gets completely dark in January.