The Friday File: According to some astronomers, space begins at the exosphere, the outermost layer of the atmosphere, about 435 miles high. According to most, it’s the Karman Line, 62 miles above Earth, and beyond which lift from the air can no longer keep winged craft aloft. To the FAA, it’s just 50 miles. Branson’s 90-minute trip took him 50 miles high. Bezos reached the Karman Line, 11 minutes roundtrip.