Sputnik 1, was launched into orbit around Earth in 1957, and since that time more than 8,300 satellites have been launched into orbit at various altitudes, some with people aboard. Many of those satellites have long since burned up in the Earth’s atmosphere due to orbital decay. Others, mainly occupied by humans, have successfully reentered the atmosphere to either land on the ground or splashdown in the ocean.
The really cool thing is that stargazers can see many of these satellites with the naked eye. It’s hard to go more than a half-hour without seeing one zip along. Most satellites move from west to east, but some are in polar orbits. The best time to see them is in the early evening for a couple of hours after evening twilight or a couple of hours before the start of morning twilight. That’s because satellites have to reflect sunlight to be visible. Just before morning twilight, and for a little while after evening twilight, there’s no direct sunlight available to us on the ground, but high in space there’s still enough sunlight to bathe satellites, sending second-hand sunshine our way. During the middle of the night, the sun is entirely behind the Earth, so all satellites pass over in total darkness.