Credit: ESA/H. Richer and J. Heyl/NASA

From the grains of sand on all the beaches on Earth to the number of stars in the sky, our universe is teeming with big numbers. Miles beneath our feet, there could lie a quadrillion tons of diamonds. With the addition of only a few zeros, big numbers transform from "countable" to the subject of guesswork. Eventually, their existence pulls at our imagination and requires the crafting of intricate scenarios. They may or may not have a presence in the universe. From the tiniest specks in the universe to the biggest numbers humanity has ever conceived, here are some of the numbers that make up our universe. Note: The numbers in this slideshow follow the U.S. numbering system, not the European one, which has different names.

Giant numbersZeroHalf a million1 Million18 Billion
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Zero

Credit: Shutterstock

The total energy that makes up the microbes, plants, oceans, planets, stars and galaxies — in other words, our entire universe — is probably … zero. That's because the negative energy in the universe most likely cancels out the positive energy, Live Science previously reported. Physicists consider light, matter and antimatter to be positive energy, while all the gravitational energy between particles has a negative charge. So, everything balances out. A ball at rest on a table has no energy, but if the ball falls off the table, it gains positive energy that is exactly canceled out by negative gravitational energy. As Live Science reported, the Big Bang threw the universe off the "table" where it was resting, as light and matter began moving. And now we are falling. But all the positive energy we gain while falling is balanced out by the negative gravitational field created by these moving particles.

Half a million

Credit: NASA

There are over half a million pieces of space junk — both meteors and artificial particles — larger than the size of a marble that orbit the Earth, according toNASA. Millions more are too small to track. This computer-generated image illustrates space junk in thegeosynchronous region, or around 22,235 miles (35,785 kilometers) in altitude above Earth's equator. And 95 percent of the objects in this picture consist of orbital debris (discarded human-made objects or pieces of objects like non-functional satellites), most of which is concentrated within 1,200 miles (2,000 km) of Earth's surface, according to NASA.

1 Million

Credit: S. Smartt/ESA/Hubble & NASA

One million planets, all capable of supporting life, could theoretically orbit a supermassive black hole, Space.com reported. Astrophysicist Sean Raymond calculated that a black hole that has a mass 1 million times that of the sun and a ring of nine sun-like stars around it could hold 400 rings of planets. Each ring would have 2,500 Earth-mass planets. In such galaxies, "You would never feel alone," Raymond told Space.com. "Other planets would loom huge in the sky." This is, of course, just one scenario of possible planetary systems in the universe — and a very cramped one at that.