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How Are Galaxies and Constellations Alike and Different?

Leonard Kelley holds a bachelor's in physics with a minor in mathematics. He loves the academic world and strives to constantly explore it.

Telling the Difference

When you look up at the clear night sky, do you know what you're looking at? There's a lot of bright lights, sure... but which of those lights is an entire galaxy, and which is just a star? What's the difference between a galaxy and a constellation? Read on to find out.




Before modern astronomy, a constellation was a shape in the sky that reflected a character from mythology. Various cultures had their own labels for those creatures in the sky, but it is from the Greek/Roman tradition that the Arabic astronomers of the past made common nomenclature. These shapes are made of stars, hot balls of plasma that radiate heat from several thousand degrees Kelvin to millions of degrees. While it may appear from our viewpoint on the Earth that these stars are in the same area of space and distance, their actual distance from us varies with each star. As modern astronomy advanced, the areas of a constellation's influence were murky. Eventually, the constellations would be given a specific area of space that was under their domain. Today, 88 constellations are recognized by astronomers.




Until the 1930s, galaxies were not known as such, but as patches of stars residing in our galaxy. But when the distance to these patches was discovered, it quickly became apparent that they were a new type of object. These objects contain billions of stars that orbit around what is called a supermassive black hole, a singularity that has a mass equivalent to millions of stars and absorbs matter, even light. Some galaxies have arms, where local clusters of stars rotate around the center at the same rate. Older galaxies are elliptical, containing no discernible arms. Others are completely irregular, perhaps the result of a merger of galaxies. Galaxies are held together by dark matter, a not fully understood substance that does not interact with light but has gravitational interactions.

Now You Know

Galaxies and constellations have one item in common: stars. Other than that, they are separate objects. Sometimes a galaxy may appear to reside inside a constellation, but this is because of our vantage point on Earth. The distance between them is millions of light years at times. Someday, constellations will no longer be in the shape that we take for granted, nor will the galaxies be in their place, for the universe is expanding and changing as time progresses forward. Our place in the cosmos moves and it moves in return. Who knows what possible constellations of the future there will be.

© 2011 Leonard Kelley


Achal dubey on July 01, 2020:

Very nice

Leonard Kelley (author) on December 18, 2017:

Can you be more specific?

Leonard Kelley (author) on December 17, 2017:

Can you be more specific?

Did NOT HELP!! on December 17, 2017:

Did not help!!

Leonard Kelley (author) on November 04, 2015:

Happy to hear, thank you!

Aarya Vanjari on November 04, 2015:

This has been a very useful guide to me!!!!!!!!!!!!!!!!

Leonard Kelley (author) on October 09, 2014:

I am glad I could help!

norlyncasulay on September 02, 2014:

#thank you so much! im finish answering my homequiz.

Leonard Kelley (author) on October 14, 2011:

Very true, but then this would not be much of an article and more of a chart.

aradhna malhotra on October 10, 2011:

differences are always written in columnar form despite in paragraphs, always remember it.