Saturday, 09 July 2016 01:43

Location, Location, Location

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By Jim Ketchum (Master Observer Certificate #3)

If any of you have ever bought or sold a house you have heard what realtors say are the three most important factors to consider, “Location, location, location.” Although it’s somewhat a tongue in cheek saying, it holds a lot of truth. The same could be said about our little corner of the universe. You probably have heard the expression “life-habitable zone.” These “zones” are extremely important to sustain life as we know it. And they are extremely rare. If Earth were any closer or farther away from the sun, life would not exist on this planet. That’s just one of over a hundred factors that determine our existence on this “pale blue dot.” If any of these factors were to change, conditions would be unfavorable to sustain life on Earth. A side benefit to our location is that we reside in a very dark place, the Earth’s moon not withstanding. In fact, Earth’s solar system resides in the darkest part of the Milky Way Galaxy’s life-habitable zone. Even more interesting, the Milky Way resides in the darkest life-habitable region of its galaxy cluster, which lies in the darkest life-habitable region of its supercluster of galaxies.


So, why is this dark location important? For an astronomer, light can be an enemy. Because of where we reside, the lights of the universe don’t blind us or limit our views. Astronomers can see virtually all of the night sky wonders, including the entirety of cosmic history. Like all galaxies, the Milky Way is filled with bright astronomical objects. If we were close to any of them, astronomical research would be seriously hampered. The brightest areas are the galactic core and spiral arms. Dust shields us from the brightness of the core. Plus, we are located hallway between two spiral arms, which themselves are partially blocked by dust clouds.


Yet, these dust clouds don’t block significant regions of the cosmos from our view. As a result we can learn a lot about the origin, structure and history of the galaxy and the universe. If we had star clusters or large objects like the Orion Nebulae in close proximity to our solar system, we wouldn’t be able to view large portions of the night sky. Imagine if the Double Cluster (NGC 884/869) were as close to us as the Pleiades (M45). It would cover one fourth of the night sky. Plus, it contains several stars that are fifty thousand times brighter than our sun. Many of its 600 stars would shine as bright as Vega. Astronomical observations would be significantly hampered.

So, the next new moon when you go out to observe the night sky, consider how lucky we are to have settled into a dark life-habitable location.


Information for this article was taken from the book Why The Universe Is The Way It Is by Hugh Ross Cosmologist Ph.D. and from “The One Minute Astronomer” by the editors of The One Minute Astronomer. Note: One-Minute Astronomer is now publishing articles at its new website

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