Radio astronomy can be recorded and pieced together in a mosaic image. The type of instrument used depends on the strength of the signal and the amount of detail needed. Observations from the Earth's surface are limited to wavelengths that can pass through the atmosphere. At low frequencies, or long wavelengths, transmission is limited by the ionosphere, which reflects waves with frequencies less than its characteristic plasma frequency. Water vapor interferes with radio astronomy at higher frequencies, which has led to building radio observatories that conduct observations at millimeter wavelengths at very high and dry sites, in order to minimize the water
Atmospheric entry not far above it) cannot create enough velocity to cause significant atmospheric heating. For Earth, atmospheric entry occurs at the Kármán line at an altitude of 100 km (62.14 mi / ~ 54 nautical mi) above the surface, while at Venus atmospheric entry occurs at 250 km (155.3 mi / ~ 135 nautical mi) and at Mars atmospheric entry at about 80 km (50 mi / ~ 43.2 nautical mi). Uncontrolled, objects reach high velocities while accelerating through space toward the Earth under the influence of Earth's gravity, and are slowed by friction upon encountering Earth's atmosphere. Meteors are also