Question

what is thermosphere

Answer 1

1. The lowest & densest layer of the earth's atmosphere. 

2. The extents of this layer is about 18km above the 
equator ,but only about 8km above the two poles. 

Answer 2

the region of the atmosphere above the mesosphere and below the height at which the atmosphere ceases to have the properties of a continuous medium. The thermosphere is characterized throughout by an increase in temperature with height.