We go about our daily lives; we work, we spend time with loved ones, run errands, pay our taxes. We have many good days and some challenging days. In the midst of it all, we might glance up at the sun or moon from time to time, or notice the stars on a clear night. However, we're usually too enmeshed in our daily activities to give such things more than a passing glance.
We see our earth as big, and in a relative way, it is. The earth is 24,901 miles in circumference, and it would take a jet plane about 40 hours to fly around it. However, our planet only seems large until we take a look at the rest of the cosmos around us.
Our Most Familiar Star
Let's start with the sun, the closest star to our home planet earth and one of the main reasons there is life here. Our sun is 92,960,000 miles away and about 109 times larger than the earth. That means you could fit around 1.3 million earths inside of the sun, and it would take a jet plane around six months to travel around it.
Yes, our sun seems big, but it's actually considered a dwarf star -- on the smaller end of things as far as stars go. By contrast, UY Scuti is the largest star we humans are aware of; it is a hypergiant around 1.7 billion miles in diameter. UY Scuti is around 5 billion times larger than our sun.
The Solar System and Beyond
The diameter of our solar system is around 5,580,000,000,000 miles -- that is, about five and a half trillion miles across. The Voyager 2 spacecraft took about 12 years to get across most of our solar system, and it was traveling at around 35,000 miles per hour.
Expanding outward from here, we have to start talking about things in terms of light years, as the scale is just too massive to discuss in miles. A light year is the distance that light can travel in one year. Light travels very fast -- 186,282 miles per second -- so that would make one light year 5.88 trillion miles.
From Galaxies to Superclusters
Astronomers estimate that our Milky Way Galaxy -- home to our solar system -- could be home to tens of billions of other solar systems. Our Milky Way Galaxy is about 100,000 light years in diameter.
The closest galaxy to ours is the Andromeda Galaxy, which is over 2.5 million light years away from earth. Andromeda is around 220,000 light years in diameter.
The Andromeda Galaxy, our Milky Way, a smaller galaxy called the Triangulum, and a few dozen even smaller galaxies comprise our Local Group of galaxies. This Local Group is on the edge of a supercluster called the Virgo Cluster, which is comprised of thousands of galaxies.
Astronomers believe there are around 10 million superclusters like the Virgo Cluster in our observable Universe.
What's Really Out There?
The Hubble Space telescope began observing and photographing a tiny sliver of outer space regularly around 2002 until 2012. (The size of the area could be likened to the size of a pencil eraser if an orbiting astronaut had held one out in front of him.) The area observed looked completely dark and black at first, but after numerous exposures spanning a decade, this is what emerged:
It is estimated that this tiny sliver of the cosmos shows around 10,000 galaxies. This image is about one 24-millionth of the entire night sky visible from earth.
Indeed, the size of our own earth is relative -- and perhaps so are the challenges we face here. Knowing the true scale of things is at once humbling and empowering. It's all about perspective, and the next time you glance up at the night sky after a busy day, you just might see things a little differently.