Though we can't see it from the ground, there are hundreds of items floating around Earth, most of them debris or "space junk."
Now the European Space Agency's Space Debris Office is urging governments to start working to remove the debris, as it could become a serious problem for satellites in a few decades.
Space junk has been orbiting the planet since 1978. It has tripled since then and is growing at an increasing rate.
"There is a wide and strong expert consensus on the pressing need to act now to begin debris removal activities," Heiner Klinkrad, head of ESA's Space Debris Office said.
"Our understanding of the growing space debris problem can be compared with our understanding of the need to address Earth's changing climate some 20 years ago."
ESA and NASA estimate that there are about 23,000 items in orbit that are bigger than 10 centimeters (four inches) across. There are hundreds of thousands more that are smaller, at 10 centimeters or less.
But even those small items pose a risk for collision and damage to satellites due to kinetic energy.
Junk travels an average of 15,600 miles per hour. A tiny object going at that speed could potentially disable a satellite or make a hole in the International Space Station.
Most of the debris comes from disused rocket stages, failed launches and broken down satellites.
Bigger items crash into each other and make smaller ones.
At the Darmstadt conference, 350 experts from around the world proposed ideas to remove large debris from the orbit at the rate of five to 10 items a year.
Some people suggested that the debris be removed by harpooning them from a robot vessel or hitting them with an ion cannon to put them on a different orbit.
There was also the idea of attaching a "solar sail" to big items which would gently encourage the pieces to go on a different course, guided by solar wind.