How far is outer space?

According to international scientific standards, outer space begins 100 kilometers above sea level. The boundary of outer space is called the Karman Line, and is accepted by NASA as well as international agencies.

The legal definition of outer space is the lowest altitude at which an orbital craft can maintain one full revolution around Earth, but this altitude is not defined. This is the threshold at which territorial airspace claims are invalid. This altitude is higher than the Karman Line; a vehicle without propulsion can sustain one revolution at 150 kilometers, while a vehicle with propulsion can sustain one full revolution at 130 kilometers.