The risk from manmade debris orbiting Earth since the launch of the first satellite in 1957, which could potentially endanger ongoing and future space programs, has been highlighted yet again in a new video released Sunday.

Space debris is made up of spent rocket parts, defunct satellites and spacecraft parts that fall off either naturally or due to collisions. NASA has been tracking about 20,000 pieces of debris that are bigger than an apple, and a total of about half a million pieces of space junk that are larger than a marble. Albeit small, these objects travel at speeds of up to 17,500 mph and can cause significant damage to any object they collide with.

The video is a time-lapse version of an interactive visualization created by Stuart Grey, a lecturer at University College London in the U.K., and was released by the Royal Institution of Great Britain. And it provides viewers with a representation of how crowded Earth’s orbit has become, as well as how things have come to be the way they are.

Beginning with Sputnik I in 1957, closely followed by Explorer I a few months later, there were already more than 200 objects in orbit over Earth when Yuri Gagarin made the first manned flight into space in 1961. Less than 20 years later, in 1980, nearly 5,000 objects in orbit could already be tracked. As space programs extended their reach, debris began to be left farther away from Earth.

Another 20 years later, in 2000, the number of tracked debris stabilized at about 9,000 objects. However, a Chinese missile test in 2007 alone added 2,000 pieces of debris, and a collision between a defunct Russian satellite and a functioning commercial satellite in 2009 added another 2,000 pieces of junk to the planet's orbit. The largest piece of debris is about the size of a bus, according to Grey’s visualization.

In 1996, a French satellite was damaged after being hit by debris from a French rocket that had exploded a decade earlier. However, instances of disastrous collisions have been surprisingly few, given the amount of debris floating around. Scientists track space junk to ensure that it doesn’t collide with functioning satellites, and the International Space Station (ISS) has to periodically move out of the way of space debris to avoid being hit.

The risk of a piece of space debris falling to Earth is quite small. Last month, an object nicknamed “WTF” fell back to Earth but was mostly burned up in the atmosphere before falling into the Indian Ocean near Sri Lanka. But, other than the debris being tracked, there are possibly millions of other pieces that have not been tracked yet.

“The greatest risk to space missions comes from non-trackable debris,” Nicholas Johnson, NASA chief scientist for orbital debris, said in a statement on the agency's website.

Scientists are working on ways to clear up space junk to avoid the huge risk it poses to other spacecraft and satellites, such as a hole in the solar array of the ISS in 2013.

The U.S. Air Force is also working on a new radar system to track space debris that is expected to come online in 2019. And Swiss researchers are working on a spacecraft that will swallow tiny defunct satellites in orbit, like Pac-Man in space.

While work on devising new methods continue, reusable rockets, such as the one used by SpaceX in its latest launch, will reduce the number of spent rockets in orbit.