How Big is the Universe?

    Earth is remarkable isn't it? An absolutely beautiful planet we live on. Not only that, it's HUGE isn't it? Well from our standpoint, yes, it is. However, when you think about how much there is out there beyond planet Earth, it's not. Actually, Earth is microscopically, infinitesimally, imperceptibly SMALL, and then some! Was I getting carried away? Not at all. I'll Help you see why. 

    The Solar System

Orbits of the objects in our solar system.

 

 Our Solar system consists of the Sun, Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune, in that order. How large is the Solar System though? Well, the Sun is approximately 93,000,000 miles from earth. So if you were to hop in a jet plane and fly to the sun, assuming that was possible, it would take you about 17 years to get there. However, we're only the third planet from the Sun. So how far is it from the Sun to outermost planet? Astronomers speculate that it's about 4.5 billion kilometers. That's about 9 billion kilometers in diameter. WOW, right? That's nothing. The universe is so vast, there is no adjective you can use to do it justice. In fact, once we measure distances outside our solar system, we have to start using a unit of distance larger than miles or kilometers... much larger. 

Light-Years

    What is a light year? Simply put, it's the distance light travels in one year. Think about that for a minute. How far can light go in one year? Well, light travels at 186,000 miles every second. So there are 60 seconds in a minute, 60 minutes in an hour, 24 hours a day, 365 days a year. That comes out to about, five trillion, eight-hundred and sixty-five billion, six hundred and ninety-six million miles, or: 5,865,696,000,000. That's how far light can go in a year. Even measuring distances in space using light-years, however, can be compared to trying to measure the distance between New York city and the island of Madagascar, using milometers.  

Going Beyond the Solar System

    So, how much space is there between the stars? Well the closest star to our sun, Proxima Centauri, is about 4 light-years away. That's just the closest star, however. Other stars are tens, hundreds, or thousands of light-years away. Now, this brings up a very interesting facet of the cosmos. Consider Proxima Centauri, it's 4 light-years away, so it would take a beam of light 4 years to reach it from Earth. Although that is correct, think about it this way: it takes light from the star itself 4 years to reach us. So guess what? If you look at Proxima Centauri, you're seeing what it looked like 4 years ago. That same principle applies to everything you look at in the night sky. You know what this means? When you look into the sky, or through your telescope at night, you're becoming a time traveler! When you look at the star Vega, you're seeing what it looked like some 25 years ago, when you look at the Dumbbell nebula, you're seeing thousands of years into the past, or when you look at the Andromeda galaxy, you're seeing some 2.2 million years into the past.


    Remember all of this as you gaze into the night sky. Like I said before, there is no adjective you can use that effectively describes the size of the universe; it's absolutely unending.