By Amanda Cardini, Editor-in-Chief
“Home” is most commonly defined in micro terms, whether it refers to a house, city, state or even country. We rarely think about our home being the entire planet, or even our planet’s home in the solar system. But in the enormous vacuum of space, a house on Earth is quite minuscule compared to the vastness that lies within the stars. In terms of the universe, humans are mere ants to the giants that surround us.
Quote from Carl Sagan on a photo of Earth taken from Voyager 1 about 3.7 billion miles away. Courtesy of Amazon
It’s easy to forget that there’s so much out there when everything you know is confined to the same planet, but that doesn’t mean there aren’t fascinating things in our universal neighborhood. Here are 10 things you should know about our place in outer space.
1. Space is vast
The size of space is so huge that we actually aren’t exactly sure how big it is. We do know that Earth only makes up about 0.0003% of the total mass of our solar system. But scientists are fairly certain that the universe is expanding, making it almost impossible to determine how large the universe really is, as this number is constantly changing. Further complicating things, is the fact that we cannot see the entire universe; we know there is more than what we can see, but we don’t know how much more. Regardless, the space that we occupy here on Earth is microscopic compared to the size of the universe.
2. Even our neighborhood in space is massive
Our solar system sits within the Milky Way, which stretches to a total of about 100,000 light-years long, and plays host to around 400 billion stars. Zooming out a little farther is the Local Group, or the local galaxy cluster to which ours (The Milky Way) belongs. The Local Group is about 10 million light-years across, and the 47 or so galaxies within it are pretty spread out; the closest galaxies to the Milky Way (called the Magellanic Clouds) are a sizable distance away, of about 200,000 light-years. Astonishingly, there may be many more galaxies within the Local Group that are invisible to us.
Artist’s rendering of our location in the Milky Way. Courtesy of NASA
Zooming out even further shows that the Local Group is part of the Virgo Supercluster, which contains around 100 galaxy clusters similar to the Local Group. The Virgo Supercluster is part of the Pisces-Cetus Supercluster Complex, which holds about 60 superclusters of galaxies like the Virgo Supercluster, and accounts for one tenth of the observable universe. Finally, the observable universe reaches about 28 billion light-years, and is still expanding. Within the observable universe are around 10 billion superclusters like the Virgo Supercluster, and about 350 billion large galaxies like the Milky Way.
If your head isn’t spinning yet, give these paragraphs a second read to let it sink in.
It’s important to note that most of these numbers are estimates, as scientists don’t fully know how many galaxies, stars, and planets exist. And to put fact number one into better perspective, the Observable Universe is 1.9 X 10^22 times larger than Earth.
3. Scientists have determined a “habitable zone” in the hopes of finding life in other parts of the universe
Affectionately dubbed the “Goldilocks Zone,” the habitable zone is the space around a star with a temperature that is not too hot and not too cold for liquid water to be present on a planet. In other words, the area is “just right.” As far as scientists are aware, water is a necessity for life, meaning that planets orbiting a star within a Goldilocks Zone are the most likely to have the capability to support life. To date, life has not been found in even our own solar system, and simply having a Goldilocks Zone does not ensure life; Venus and Mars are both within our sun’s Goldilocks Zone, yet so far we have not found solidified evidence of life on either planet.
4. Space is old
Astronaut Bruce McCandless on the first untethered space walk in Earth orbit. Courtesy of NASA
When compared to the age of the entire universe, human life is young. Current estimates date the universe to about 13.8 billion years old, which is determined based on the age of stars. To this end, it is difficult to know if other forms of life existed in other parts of the universe before humans arrived. If, for instance, life existed in a far away galaxy and tried to communicate with forms of life in our own galaxy, it could take billions of years to reach us, just because of the sheer size of space. By the time it reaches us, the life form could already have been extinct for a long, long time.
5. The universe is changing
There’s no shortage of theories on how the destruction of the Earth will occur, and many of them are rooted in scientific fact. Asteroids, planet collisions, and black holes are all real threats, but scientists agree with certainty that one day the sun will burn Earth away. Over the coming billions of years, the sun will become brighter and brighter as it burns hydrogen. This will eventually (in about 4 or 5 billion years) result in the evaporation of water on Earth, causing it to become a dry, desolate place devoid of human life.
Andromeda (left) and the Milky Way at a potential stage in their collision. Courtesy of NASA
But also in the distant future, the Milky Way and nearby galaxy Andromeda will collide. Some four billion years from now, the two galaxies will fly through each other, and continue to come together and fly apart for a billion years. After the collision, stars will have relocated, constellations will take on different forms, and the two galaxies will have merged, creating a new giant galaxy. Nearly everything we know about our place in space will be rewritten, changed forever and remapped.
Perhaps the most fascinating thing about space is how little we really know. Yet as technology evolves, we will only continue to learn more and more about the universe. Its vastness and age may be humbling in the way it makes us feel infinitesimal, but there’s no denying the incredible talent it takes for us to learn anything about our massive vacuum of a home.
If you need any more help feeling utterly small within the universe, check out this video.