How many satellites does NASA use to study Earth?
Last night, your brother helped you look at stars through your new telescope. While looking at the night sky, you saw a bright dot moving in a straight line over your head. You asked your brother, “How can a star move like that?” He replied that the moving bright dot was probably a satellite orbiting the Earth. Satellites are objects that travel around other objects. Our Moon is a natural satellite because it orbits Earth. Artificial Satellites carry instruments that can make measurements for scientists on Earth. Scientists are able to use these measurements to help people. There are thousands of satellites orbiting Earth. A part of NASA, called the Earth Science Enterprise (ESE), uses about 20 of these satellites. NASA’s ESE uses these satellites to study how the Earth changes today and predicts how it might change in the future. These satellites can also study how people affect Earth (such as by polluting the air or water). NASA places satellites into orbit for many private groups an
