Polar Ring Galaxies: Strange Galaxies Indeed!


NGC 4065A

NGC 4065A

It’s not unusual to come across strange things in the universe.  The unbelievably enormous size of the universe makes it a sure bet that we will continually find oddities!  In my opinion, Polar Ring Galaxies fall into the category of not only odd, but quite rare as well.

According to the Astronomical Institute at St. Petersburg State University in Russia, there have only been 157 Polar Ring Galaxies identified.   A Polar Ring Galaxy (PRG) is type of galaxy where an outer ring of gas and stars rotates over the poles of the galaxy.  A good example of this is NCG 4065A.  This is odd because you would expect that these rings of gas and stars would occur along the axis of rotation like our galaxy, the Milky Way (a spiral galaxy).  In order to help you visualize this, think of the rings of Saturn – they rotate above the equator, not the poles!

NGC 2685

NGC 2685

OK, PRGs occur on a galactic scale, not on a planetary scale like Saturn – so what could cause something like this to happen?  The leading theory is that this is the collision of two distinct galaxies in the distant past.   During the collision, which by the way takes millions of years to unfold, the ring material is stripped from the passing galaxy to form the perpendicular ring – ONLY if the galaxies collide at right angles (orthogonally) to each other! 

What objects to you find odd in the universe?  Let us know.



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