SSPPAACCEE...

space is a very huge place. so huge that in fact we had to make a new measurement just to be able to measure it without having such big numbers. most of space is measured in light years or AU (distance from sun to the earth is 1 AU). light ears are bigger and would cover most of the universe. 1 light year is 9,500,000,000,000 kilometers. a lot. 1 AU is 149597870.691 kilometers. so that means a kilometer (which i don't call walking distance) is really a very very short distance, compared to the rest of the universe.

the distance between Ganymede and the sun is measured in AU. It is about 5.2 AU. It was not far
enough to be measured in Km, and to short to be measured in light years. yet if we took a spaceship
and flew to Ganymede, it would take somewhere around a year and eight months to get there.

space is huge, so big that we will probably not know when we can have technology to be able to go out and look at other places beyond our solar system. for now be thankful we have an awesome planet to live on.