Food for Thought: The Size of the Universe

Courtesy of http://www.windows2universe.org/the_universe/images/galaxies/m31_small.gif

 

In our hectic lives and busy schedules, it is easy to get caught up in the massive amounts of work to be done. We sometimes barely have enough time to even think. We then miss out on many things. For example, when was the last time you looked at the moon or the stars and thought about them. They look so big and yet so small at the same time. If you just reach your hand out, you may even be able to hold them in palm. Of course, the reality is that they are massive celestial bodies and much further than you could imagine.  The Universe is much bigger than just our human civilization and even the planet Earth.

The universe is so massive that it boggles human comprehension. Light which seems almost instantaneous, actually still has a finite speed of 300,000 km/s. The fastest human spacecraft was Helios 2 and it had a top speed of 4216.6 km/s and that wasn’t due to its propulsion but instead due to the acceleration of gravity caused by it falling into the Sun. The speed of light truly is   insanely fast but still minuscule compared to the vastness of space and space deserves its name.

You may have heard of the term “light-years ahead” in comparisons as a unit of time. That is incorrect. Light-years are actually units of distance. It is the distance that light travels in a year. That is approximately 10 trillion kilometer. That is 249,532,127 times the circumference of the Earth.

And yet the nearest stars to the Earth are multiples of light-years away. The closest star system to our own solar system is Alpha Centauri and that is 4.22 light years away from the Earth or 40.22 trillion kilometers away.

Even more shocking is the fact that the light, the image, of the stars we’ve seen are merely the light that star emitted in the distance past. For example the light of a star that is 15 light-years away from us is actually 15 years old. On greater scales like billions of light years away, it is possible that such stars have already ceased to exist but the image of their destruction won’t reach us for billions of years.

Furthermore, although space truly is full of empty space, the amount of things in the observable universe is absolutely staggering.

There are an estimated 100 billion stars in the Milky Way. 100 billion stars. In the observable universe, there is  an estimated 100 billion galaxies. 100 billion galaxies! mind = blown

Source

Bennett, J. O. (2008). The cosmic perspective. San Francisico, CA: Pearson Addison-Wesley.

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