Double Star or Binary Star Systems

Two Stars in the Sky

Is this what Earth's sky would look like with two suns?

We humans have evolved on the planet Earth knowing only one sun lighting our sky.  Did you know that there are double star systems out there in the Universe?

Double Star or Binary Star systems contain two stars that rotate around their common center of gravity.  In these systems, the brighter or larger star is referred to as the primary star and the smaller or dimmer star is referred to as the secondary star.  Sir William Herschel discovered binary star systems in 1802 and was the first person to refer to them as binaries.  Believe it or not, these types of systems are not very rare and since the invention of the telescope many have been identified.

Binary Star System

A White Dwarf Binary Star System

The Washington Double Star Catalog, which is a database of visual double stars published by the United States Naval Observatory contains over 100,000 pairs of double stars.  Some of the better known binary stars include Mizar – which can be found in the Big Dipper, and Acrux – which can be found in the Southern Cross.

So how do these systems form?  One thought is that a double star system could be formed by the gravitational attraction of a large star capturing a smaller star.  Given the vast distances between stars in our universe, this not a very likely explanation.  A more common belief is that they are created by fragmentation of the molecular cloud during the accretion stage of stellar formation.

Do you think that planets could also exist around these double star systems?  What would our sky look like if we orbited two stars?

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3 Responses to “Double Star or Binary Star Systems”

  • Noe Caperon says:

    I think it is grate &thank you for sharing


  • Terry says:

    Would`t it be wonderful to have two sun instead of one. TThis would solve all our energy problems. We would no longer have to rely on nuclear power and fossil fuels just to heat and cool our homesetc, etc,etc.


    Tatyana Amelina replied:

    A great phenomenon. Two suns would save the world a lot of money, but at the same time they would double or triple the cases of skin cancer and many other types of cancer especially bone cancer. Cystic fibrosis also will be on the list


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