In context of spaceflight, a satellite is an artificial object which has been intentionally placed into orbit. Such objects are sometimes called artificial satellites to distinguish them from natural satellites such as Earth's Moon. 

In 1957 the Soviet Union launched the world's first artificial satellite, Sputnik 1. Since then, about 6,600 satellites from more than 40 countries have been launched. According to a 2013 estimate, 3,600 remained in orbit. Of those, about 1,000 were operational; while the rest have lived out their useful lives and became space debris. Approximately 500 operational satellites are in low-Earth orbit, 50 are in medium-Earth orbit (at 20,000 km), and the rest are in geostationary orbit (at 36,000 km). A few large satellites have been launched in parts and assembled in orbit. Over a dozen space probes have been placed into orbit around other bodies and become artificial satellites to the Moon, Mercury, Venus, Mars, Jupiter, Saturn, a few asteroids, and the Sun. 

Satellites are used for many purposes. Common types include military and civilian Earth observation satellites, communications satellites, navigation satellites, weather satellites, and space telescopes. Space stations and human spacecraft in orbit are also satellites. Satellite orbits vary greatly, depending on the purpose of the satellite, and are classified in a number of ways. Well-known (overlapping) classes include low Earth orbit, polar orbit, and geostationary orbit. QUESTIONS:

Q1:
1. What sorts of objects are satellites?
2. What is the definition of a satellite?
3. What kind of thing is a satellite?
Q2:
1. What was an accomplishment of the Soviet Union in 1957?
2. What did the USSR do in 1957?
3. In 1957, what was the Soviet Union able to do?
Q3:
1. What did the Soviet Union call their first satellite?
2. What was the name of the first Soviet satellite?
3. What name did the Soviets give to their first satellite?
Q4:
1. What is the number of satellites in orbit?
2. How many satellites currently orbiting the planets?
3. What is the number of satellites in space?
Q5:
1. What planets do satellites orbit around?
2. What are the planets with satellites around them?
3. Which planets are orbited by satellites?
Q6:
1. Do satellites ever become debris?
2. Does it ever happen that satellites become debris?
3. Are satellites ever turned into debris?
Q7:
1. How fast do satellites go?
2. What is the speed of satellites?
3. At what speed do satellites travel?
Q8:
1. What is the usage of satellites?
2. What is the function of satellites?
3. What's the main purpose of a satellite?
Q9:
1. What are some usages of satellites?
2. What are a couple functions of satellites?
3. What's some main purposes of a satellite?
Q10:
1. What is one usage of satellites, besides observation?
2. What is a function of satellites, other than observation?
3. What's a main purposes of a satellite in addition to observation??
