Scientists have demonstrated that the universe is expanding in size, with galaxies moving farther from one another (objects within a alaxy, like the planets in our solar system, donít move away from each other, however, because they are held together by gravity). Because distances in space are so huge, scientists often use the measurement of light-years instead of miles to describe them. A light-year is the distance that light can travel through space in one year, which is 5.88 trillion miles (9.46 trillion kilometers). The farthest galaxies that can be seen from Earth are thought to be 12 billion to14 billion light-years away. That means that the observable universe has a diameter of up to 28 billion light-years. And thatís just the galaxies we can see imagine if we could stand at the edge of one of the farthest galaxies, look through a telescope, and see galaxies extending 14 billion light-years from there. The potential size of the universe is mind-boggling. It is nearly impossible to imagine the distance of one lightyear, let alone 14 billion of them!