The Navajo are the second largest tribe in the U.S. and they have the largest reservation stretching across Colorado, Utah, New Mexico and Arizona with over 25,000 square miles. They were also among the largest group of Indians to migrate to Los Angeles in the 1950s and 60s.
The ionosphere is a shell of electrons and electrically charged atoms and molecules that surrounds the Earth, stretching from a height of about 50 km (31 mi) to more than 1,000 km (620 mi).
The lower part of the thermosphere, â from 80 to 550 kilometers (50 to 342 mi) â contains the ionosphere, which is so named because it is here in the atmosphere that particles are ionized by solar radiation.