Sirius: Brightest Night Time Star

Jan 2, 2020


Sirius is also known as the Dog Star. It lies at a distance of only 8.6 light years in the constellation Canis Major or the Big Dog. Sirius is the fifth closest star to the earth and brighter than all of them.
Credit NASA, ESA, H. Bond (STScI), and M. Barstow (University of Leicester)


Of the thousands of stars humans can see at night with our eyes alone, Sirius is the brightest star we can see. 

Sirius is also known as the Dog Star.  It lies at a distance of only 8.6 light years in the constellation Canis Major or the Big Dog. Sirius is the fifth closest star to the Earth and brighter than all of them. 

Sirius is bright because it is so close to the Solar System. Other stars like Canopus are brighter but appear dimmer because they are farther away. 


The ancient Egyptians watched the rising of Sirius which warned farmers of the annual flooding of the Nile River.  


To the unaided human eye Sirius appears as one star. Astronomers know it is a binary system of two stars where the brighter star is known as Sirius A while the much fainter star is Sirius B, also known as the “Pup." The two stars orbit each other in 50 years and are separated by a distance 20 times the distance of the earth and Sun.  


Sirius is about twice as massive as our Sun and 25 times more luminous, while the fainter Sirius B is 10,000 times less luminous and is about the size of the Earth.  The age of this binary system is estimated to be about 200 to 300 million years.   


Along with the stars Procyon in Canis Minor and Betelgeuse in Orion, Sirius forms what is known as the Winter Triangle. The easiest way to locate Sirius is to use the three stars in the constellation Orion’s belt as pointers. 

Sirius can be seen for the next month rising in the southeast evening skies between 8:30 and 9:00 p.m.   


Sirius is well known for its strong twinkling as its light passes through our atmosphere.  So go out some clear evening and enjoy the show.