d_dhankhar
Member
AT THE EDGE OF SPACE: this photo taken on July 22nd by astronauts onboard the International Space Station. The space station was located some 320 km (200 miles) above Mongolia at the time of the display. Astronauts pointed their camera out a north-looking window where the midnight sun illuminated the clouds. The black expanse of Earth at the base of the snapshot is Russia.
The electric-blue band, a noctilucent cloud, lies approximately 83 km (51 miles) above Earth's surface. The sky at that altitude is space-black. It is the realm of meteors, high-energy auroras, and tiny crystals of ice that glow blue when struck by sunlight. Noctilucent clouds (NLCs) are made of those crystals; how they form in the extremely-dry upper reaches of Earth's atmosphere is a mystery.
The view from the ISS is stunning, but space travel is not required to see NLCs. These mostly-polar clouds have been sighted in recent years from Earth's surface as far south as Oregon, Washington, Iran and Turkey.
Noctilucent clouds really do hover "at the edge of space."
The electric-blue band, a noctilucent cloud, lies approximately 83 km (51 miles) above Earth's surface. The sky at that altitude is space-black. It is the realm of meteors, high-energy auroras, and tiny crystals of ice that glow blue when struck by sunlight. Noctilucent clouds (NLCs) are made of those crystals; how they form in the extremely-dry upper reaches of Earth's atmosphere is a mystery.
The view from the ISS is stunning, but space travel is not required to see NLCs. These mostly-polar clouds have been sighted in recent years from Earth's surface as far south as Oregon, Washington, Iran and Turkey.
Noctilucent clouds really do hover "at the edge of space."