In this blog post – the size of space: relatable context – we’re going to break down the vastness of space and make it more understandable in human terms. We’re going to be discussing some HUGE numbers here, so ready your mind.
Let’s get the obvious out of the way first; space is big. How big exactly? Well, that’s something that we often underestimate. To put it into perspective, in 1995, scientists managed to point the Hubble Telescope at the sky near the Big Dipper. This was a small spot that wasn’t bogged down by light pollution from the other stars in the area. The telescope collected 150 hours of data and found over 3000 galaxies in a magnificent picture that’s now known as the Deep Field Image.
Now, to put that into perspective, raise a ballpoint pen to the night sky. The tip of the pen compared to the entire night sky is what the Hubble Telescope captured. This means that 3000 galaxies were present in that relatively small speck of the universe. These galaxies were present in an area that was approximately one two-millionth of the entire night sky as seen from Earth. Later, the Hubble Telescope received a few adjustments, and a long exposure image was taken over four months. Ten thousand galaxies were observed in the same area. Mind = Blown, right? And we’re just getting started.
The Size of Space: Putting Things into Perspective
The average human is around 1.7 meters in height. The diameter of Earth is around 12,700 kilometers, which means that nearly 7.5 million humans will need to lie down head to toe to line the circumference of the planet. That is the entire population of Bangkok, Thailand.
The astronauts of Apollo 11 had to travel over 380,000 miles to reach our moon. It doesn’t seem like a lot on paper, but get this; you will be able to fit all the planets in our solar system between Earth and the moon (yes, even that monster that we know as Jupiter). Even then, you will have 4,392 kilometers left over. Saturn, the second biggest planet in our solar system, can fit around six Earths side by side in just the area of its rings.
Our Solar System
The Sun in our solar system is a relatively small star compared to others in the galaxy. It still has a diameter of 1.4 million kilometers and is around 109 times the size of Earth. It weighs 333,000 times more than the Earth and is so large that it can fit 1.3 million planets the size of Earth. The Sun makes up 99.86% of all the mass in the solar system.
But, as we mentioned earlier, the Sun is still minuscule compared to some of the other stars in the galaxy. For example, the star Arcturus is 16,000 times the volume of the Sun. The Alpha Scorpii A star is 690 million times the volume of the Sun. VY Canis Majoris is 2.9 billion times bigger in volume than the Sun!
Considering that Sun is just a small star in our galaxy, we should look at the more massive Milky Way too. The Milky Way holds around 100 to 400 billion stars. And there are probably billions of galaxies in the observable universe (more on that later). But why have we used the word “probably” there? Why are we not sure about the numbers?
Well, simply put, it’s because the data we receive is based on the time it takes for the light to reach our telescopes, and some of this light that’s reaching us now is billions of years old. This means that we are studying the stars and galaxies in their infancy right now. Some information from certain galaxies is actually dated at a billion years after the Big Bang occurred. This means that we’re effectively looking back in time!
Measuring Distances in Space
We know by now that our solar system resides in a galaxy known as the Milky Way. But what’s the size of the Milky Way?
What Are Lightyears?
First, we should learn what lightyears are so that we can understand the distance and size of space properly. We measure distances in space through lightyears since that is easier to measure than miles and kilometers. A lightyear is basically what the name suggests. It’s how far light travels in a year. We know that the speed of light is 299,792,458 meters per second. When we multiply this by all the seconds in the year, we come to the conclusion that in one year, light travels 10 trillion kilometers. Let that sink in for a moment.
On a more relatable scale, light from Sun takes 8 minutes to reach Earth. This means that the Sun is 8 light minutes away from the Earth.
To put that into perspective, consider the fact that the diameter of the Sun (the biggest object in our solar system) is 1,391,000 kilometers. Well, the Milky Way is approximately 100,000 lightyears in diameter. That is roughly 950,000,000,000,000 kilometers!
The Milky Way
But, even the Milky Way galaxy is small compared to many other galaxies in the universe. The IC 1011 galaxy is six times the size of the Milky Way at 600,000 lightyears across. Even imagining all that could exist inside the galaxy can blow our minds! As we discussed above, a single image of the Hubble Telescope in 1995 captured 3000 galaxies. Each galaxy has millions of stars, and each star may have its own solar system of planets revolving around it.
Our Cosmic Neighborhood
Astronomers also have a good idea as to what our cosmic neighborhood of galaxies looks like. If you look at our surroundings, around one billion lightyears around the Earth, you will be able to see some superclusters. Each supercluster holds different groups of galaxies that are strung together by gravity. The Milky Way belongs to the Virgo Super Cluster and is basically a small side character to the larger group. The massive Virgo Cluster dominates in our supercluster with 1,300 galaxies.
The “nearby” Coma Supercluster is an unfathomable size of 500 million lightyears across and 300 million lightyears in width. The biggest supercluster of galaxies in our surroundings is the Horologium Supercluster. It stretches to an insane half a billion lightyears!
Now, what is the exact size of space in its entirety? No one knows exactly how vast the universe is since it could very well be infinite. Want to know something really crazy? Some scientists think that the universe could actually loop in on itself, which means that there is no “beginning” and no “end” of the universe!
Scientists have been able to see the universe to about 13.7 billion lightyears away and have calculated that the universe is at least 13.7 billion years old. However, the universe is still expanding (another topic for another day, but just know that space is constantly expanding), which means that the exact size of the universe is still unknown. However, taking the expansion of the universe into account, and if we place ourselves in the center, we can say with a degree of certainty that the observable universe is about 93 billion lightyears across.
Even after all these things are put into perspective, it is still hard to imagine the proper scale of the universe in our minds. The best part is that we continue to learn new things as we continue to gaze out at the stars from our humble abode here on Earth. In this blog post – the size of space: relatable context – we’ve tried to explain the size of the universe in understandable terms, but let’s face it, the universe is just too big for our mortal brains to comprehend. However, we owe it to ourselves to continue to learn as much as we can about this massive expanse we know as “space.”