Astronomy: Breaking Down Distance Beyond the Sun Through Space and Time.

With all of the latest buzz surrounding Pluto and the data that human kind has been privy too thanks to New Horizons, my family and I have picked up the conversation of space and time and their relativity to each other. I realized something through the course of these conversations, I basically knew the concepts, but had a difficult time articulating when it came to putting the concepts into words.
So, it began.
 I sat down to brush up on the basic Astronomy that I was taught in High school and college. When I was through, I was excited at the new found firm grip I had on the numbers, terms, and what they meant. In the hopes that I am not the only one on the planet who enjoys the subject yet, has a hard time keeping all the facts straight…..

….I decided to write about it.

     When we talk about the speed of light we are talking about how much distance light can go in any given time frame, i.e. seconds, hours, even years. It is the basis for which we measure out from the Earth to any given object in space. It is a constant because it is the fastest speed known to man. In one second light can travel 186,170 miles or 670,616,629 mph! That is a mind blowing rate of speed! The Earth is approximately 24,860 miles around. If you were traveling the speed of light, you could circle the globe 7.5 times in 1 second! For more perspective consider this, NASA has reported the highest rate of speed that man has ever achieved is on the Apollo 10 at 24,816 mph or 413.6 miles per second. That is 450 times slower than the speed of light! Now, think of this, the range of speed we can go from one of the slowest we know (sloth) .003 mph to the fastest we have ever gone as humans (Apollo 10) at 24,816 mph, is a wide one. It has many variations in between. Going even further past the speed of Apollo 10 we cap off at 670,616,629 mph, the speed of light. Reinforcing that the speed of light is a constant, it goes no faster or slower.

     Now that we know the basics of the speed of light we can discuss how measurements that sound like time are actually talking about distance.

     First, we will cover AU. AU stands for Astronomical Unit and refers to the distance from the earth to the Sun. 1 AU = 93,150,000 miles. To make it clear, remember that the speed of light is 670 million mph. This means, that it takes light 8 seconds to reach the earth from the sun. For example, if we were able to switch the sun off and then back on, it would take only 8 seconds for the light of the sun to reach us again after it was turned back on. Most objects in our own solar system are measured in terms of AU. Mars is 1.523 AU from the sun which is about 140 million miles or 1.523*93 million miles.

     Next, we will talk about Light Year. We have discussed the speed of light in terms of seconds (186,000 miles per second). We have talked about it in terms of hours (670 million miles per hour). How many miles can light travel in one year? 5.9 trillion miles! There are 65,555AU in a light year. Meaning, to accomplish traveling the 5.9 trillion miles it takes to cover a light year we would have to travel back and forth to the sun almost 33,000 times. To travel a light year, or 5.9 trillion miles you would have to go passed Pluto deep into the Oort cloud.

     Finally, the parsec. A parsec is 3.26 light years. 3.26*5.9 trillion. Can you imagine the size of that number? That brings us to the reason for this odd terminology. Like any other enormous numbers in math, Scientists abbreviate them to make it easier to read and get the idea. This is especially helpful in dealing with numbers that are almost too big to grasp. To give perspective to the parsec, the closest star to the sun Proxima Cetauri. It is 1.295 parsecs from the sun or 4.22 light years.

     

     I hope this article has been helpful and you are walking away with a refresher or new knowledge. If you do still have questions, feel free to ask in the comments.

Happy Space Travels!

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