Our Place in the Universe Back | Up | Next

We live on a very nice planet that goes around an ordinary star in a quiet neighborhood in one of the outer spiral arms of the Milky Way galaxy.

Our Sun is one of an estimated 100 to 200 billion stars in the Milky Way. Our galaxy is part of a cluster of about 50 galaxies called the Local Group, of which the Milky Way and Andromeda galaxy are the dominant members. Our local group is also part of a larger group called the Virgo Supercluster of Galaxies which contains about 100 galaxy groups and galaxy clusters.

Markarian's chain is a group of galaxies at the heart of the Virgo supercluster of galaxies.

Astronomers estimate that there are millions of superclusters in the observable universe containing hundreds of billions of galaxies. Recent discoveries have found that galaxies tend to cluster together with giant voids in between them, like a foam of bubbles.

Scientists are not sure how large the universe is, but the latest estimates give it a diameter of about 93 billion light years.

Since 1 light year equals about 6 trillion miles (9.65 trillion kilometers), 93 billion light years equals 6 trillion x 93 billion, which equals 558,000,000,000,000,000,000,000 miles, or 898,000,000,000,000,000,000,000 kilometers.

That would be 558 sextillion, or 558 trillion billion miles (898 sextillion kilometers).

The universe is a very big place.

Mysteries of the Universe

Measuring the mass of galaxies and their rates of rotation, astronomers have found that there must be some type of matter that we can't see exerting a gravitational influence. They have named this "dark matter". Scientists don't know what this dark matter is.

Recently, astronomers have discovered that the expansion of the universe after the Big Bang is actually speeding up. The Big Bang occurred some 14 billion years ago and created both space and time. They don't really know why the expansion is accelerating, but "dark energy" has been given as a possible reason. They also don't know what this dark energy might be.

One of the oddest things that we have discovered about the universe is that visible light and ordinary matter make up only about 4 percent of the "stuff" that makes up the universe. 22 percent is believed to be dark matter, and 74 percent dark energy. This means that 96 percent, or the overwhelming majority, of the universe is made of something unknown, and we have no idea what it is.

Our Place in the Universe - The Bottom Line

The universe is a really big place. And the truly amazing thing about it that we are made up of the same stuff as the stars, and that this stuff has developed a consciousness and ability to contemplate itself.

Back | Up | Next