Orbits explained: Space is surprisingly close, but it's really hard to stay there

Space is closer than you might think -- about 62 miles up, only a little farther away from you than San Jose is from San Francisco. Heck, you can get halfway to space in a balloon. But the hardest part about space, isn't so much getting there as staying there. That's where the idea of orbiting comes into play. Once you accomplish the hard work of getting a spacecraft into orbit, you can get years of use out of it as it loops more or less effortlessly around the planet on its own invisible track. More

(Source: CNET - Jul 22)