* Impossible to scale small enough on-screen vs the size of the Universe.
** Impossible to scale small enough on-screen vs the size of the Milky Way Galaxy.
Our solar system comprises the sun and all the planets that orbit it, along with countless asteroids, moons, and dust. The Milky Way galaxy is made up of hundreds of billions of stars like our sun, many with their own planets and moons. In basic terms, the universe is just all of the galaxies; billions and billions of galaxies. Each planet in each solar system in each galaxy is unique. Understanding the scale of the universe is not easy, so let’s break it down.
The Solar System
As most people know, our solar system contains the planets Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune, all connected by gravity and orbiting the sun. Five dwarf planets, including Pluto, can also be found in our solar system (see also Planet sizes in the Solar System). While many people recognize Neptune as being the furthest star from the sun, our solar system does not end there. The end of the solar system can be defined by two different characteristics; the sun’s magnetic field reaches to the heliosphere (18 billion km from the sun) and its gravitational effect can be felt up to 2 light years away.
How big is the solar system?
Most commonly, our solar system in its entirety is said to have a diameter of 287.46 billion km, a length which could fit 36 billion Earths. As large as this number sounds, our solar system compared to the Milky Way galaxy is about 160 million times smaller.
The Milky Way
The Milky Way is a galaxy composed of approximately 400 billion stars. So far, scientists have discovered 2500 stars that have planets orbiting around them, and more are discovered all the time. The Milky Way has a staggering diameter of at least 100,000 light years. All those stars take up a lot of space! While the Milky Way is not the smallest galaxy found in the universe and is in fact slightly above average in size, it is not nearly as large as the largest galaxies. The stars in the Milky Way are also on the smaller side; our Sun is larger than 90% of the stars found in this galaxy. The Milky Way is approximately 890 billion times the mass of the Sun. Believe it or not, the Milky Way galaxy is around 930,000 times smaller than the observable universe.
The Universe
The universe as it is currently understood measures around 93 billion light years in diameter. Countless billions of galaxies make the universe their home (potentially up to 2 trillion), and that is only the observable universe. The observable universe is home to roughly 10-billion superclusters and an estimated 350-bilion large galaxies similar in size to the Milky Way. The observable universe houses a mind boggling 30-billion-trillion stars. Even trying to imagine the size of the observable universe is nearly impossible, but that doesn’t even consider the size of what we don’t know. The size of the unobservable universe is obviously and unfortunately unknown. The universe is so large that several quintillion milky ways could fit inside it. It is almost impossible to comprehend just how many galaxies, stars, and planets are found in our universe!
Bonus Comparisons
The IC 1101 galaxy is the largest galaxy identified in the known universe, found almost a billion light years away from Earth. The M87 Black Hole is galaxy 55 million light-years away; at its center you’ll find a supermassive black hole. The Hercules A galaxy is found 2.1 billion light years from Earth. It is a bright radio source near the constellation Hercules.
IC 1101 Galaxy
The IC 1101 galaxy is the largest known galaxy at 60 times the size of our Milky Way galaxy. It is estimated that the IC 1101 is as wide as 6 million light years in diameter, and it contains about 100 trillion stars. It is proposed that this galaxy was formed by the collision of many other galaxies similar in size to the Milky Way. The IC 1101 galaxy is so bright that it would be matched by a minimum of one trillion suns!
M87 Black Hole
The M87 black hole has a mass between 3.5 billion and 7.2 billion times that of the sun. The diameter of this galaxy is estimated to be 240,000 light-years, roughly double the size of the Milky Way. The black hole is so large that it would take 2.98 million Earths in a row to span its entire length. As crazy as it sounds, the M87 black hole could fit our entire solar system inside of it. It’s a good thing we are 55 million light years away!
Hercules A Galaxy
The Hercules A galaxy is almost 1000 times more massive than the Milky Way. It contains a central black hole that is also 1000 times larger than the black hole in the Milky Way. Visualizing this galaxy is virtually impossible since it dwarfs everything we can observe in our solar system.
Connecting It All Back to Earth
Perceiving the size of the universe, solar system, and milky way galaxy is tricky since we can’t really compare them to anything that we can actually visualize. Comparing them to our Earth may help put things in perspective, so here are some interesting approximations:
- If our Solar System (from the Sun to Pluto), was a Soccer/Fútbol field, the Earth would be the size of a small marble on it.
- If our Milky Way Galaxy was the size and volume of the Pacific Ocean, our Solar System would be like a kid's bucket of water and the Earth would be like a small grain of sand in it.
- If the observable Universe was the size of an Olympic swimming pool, the Milky Way Galaxy would be the size of a pin head thrown in it.