Really far! As you probably know, the closest star to Earth is none other than our friendly sun - and that's almost 93 million miles away! To give you an idea of how far away that is, if you were driving in a car at the same speed you go on a highway, it would take you 177 YEARS to get from here to the sun.

The next closest star to us is called Proxima Centauri and that's almost 300,000 times farther away from Earth than the sun is! Because stars are so far away, measuring the distance to them in miles isn't very useful - you always get huge numbers. Instead, astronomers measure distance by how long it would take light (which can travel 186,000 miles every second) to go somewhere. So for example, since it takes light about eight minutes to get to the Earth from the sun, we say that the sun is eight light-minutes away from Earth. Similarly, Proxima Centauri is 4.2 light years away from Earth.

So those are the closest stars. What about the ones further away? Well, as a star gets farther and farther away, it gets dimmer, so the farthest stars you can see with your eyes when you look out at the night sky are about 4,000 light years away. That means it takes light 4,000 years to travel from those stars to your eyes!

How about even farther? Well, the solar system lives in the Milky Way galaxy, which is a huge blob of stars. The center of the Milky Way galaxy is 27,000 light years from Earth, while the entire galaxy is about 100,000 light years across. But you can only see stars that far away with a telescope.

What about even further? Sure! The Milky Way is just one of tons of galaxies - one of the closest galaxies to us is the Andromeda galaxy, which is about 2.5 million light years away. It's so far away that you can't see individual stars in it - you just see an glowing blob. The very farthest galaxies we can see with our fanciest telescopes are about 13 BILLION light-years away - that means that the light that we see from those galaxies left them not very long after the universe was born! So when you look at galaxies that are very far away, you're also looking back in time at what the universe used to look like. It is the closest we've got to a time machine!

It varies drastically. The closest star is the sun, which is about 93 million miles away. Farther than that, we use the term "light years" to tell distance. A light year is the distance light can travel in a year. Although it looks instantaneous to us, light actually has a speed, about 300,000,000 meters every second. That's fast enough to get to the moon in about 1.2 seconds. We haven't been able to build anything that can travel nearly as fast as light, but it is a good way to measure distance. Pluto is about 6 hours away by light. The nearest star is four light years away, or about 23,500,000,000,000 miles. The galaxy is about 100,000 light years across, or about 588,000,000,000,000,000 miles (588 quadrillion miles). This sounds ridiculous but is true. That means that if you were to drive a car from one side of the galaxy to the other (assuming someone built that road), at 80mph it would take 839,000,000,000 years. Since the universe is 13,000,000,000 years old approximately, it would take well over the entire lifetime of the universe to travel that distance by car.

The short answer is REALLY REALLY FAR away. The distance between galaxies is even larger, so some stars in other galaxies are millions or billions of light years away. Space is big.

The closest star to Earth is the sun, which is 92,960,000 miles from earth. The furthest group of stars visible to the naked eye is the Andromeda Galaxy, which is 2.3 million light years away [1]. The furthest stars found by astronomers in 2013 was 13.1 billion light years away [2].

[1] Dunbar, B. (2006, October 3). Amazing Andromeda Galaxy. Retrieved October 3, 2014, from http://www.nasa.gov/vision/universe/starsgalaxies/spitzerf-20061003.html

[2] Croswell, K. (2013, October 23). Farthest confirmed galaxy is a prolific star creator. Retrieved October 3, 2014, from http://physicsworld.com/cws/article/news/2013/oct/23/farthest-confirmed-galaxy-is-a-prolific-star-creator

There is a wide spectrum of distances that a star might be from Earth. For instance, our solar system's sun, which is just shy of 150 million kilometers away from the Earth, is the closest star to us. After the sun, though, the next closest star is 4.3 light years away, where 1 light year is about 10 trillion kilometers! And the farthest stars that have been measured are around 13.1 billion light years away (around 10²³ kilometers away)!

Some stars are closer than others. The sun, the nearest star, is 150 million kilometers, or eight light minutes (that is, it takes light from the sun eight minutes to reach the Earth, due to the distance from the sun to the Earth). The nearest star in the sky other than the sun, Proxima Centauri, is four light years away.

I don't know how far away the "average" star in the night sky is. There are many many stars that are far, far away, but are too faint in the sky for the human eye to see them.