It’s been nearly 60 years since mankind first put the first satellite into orbit, and ever since then, we’ve left a lot of junk orbiting our Earth.

The first satellite to be launched into orbit was Sputnik-1 by the Russians in 1957. That has since expanded to hundreds of satellites by the year 2000, which included thousands of pieces of “space junk” — debris from leftover rockets and satellites. Today, that number has expanded to about 20,000 tracked space debris, according to an NPR report.

You can see a visualization of the staggering amount of space junk circling our planet in the video above.

Generally, the debris has to be over 5 centimeters, or 2 inches, to be tracked. There are millions of debris smaller than that that can’t be tracked.

A few events created a large amount of the space debris.

One was an anti-satellite missile test by the Chinese in 2007, when a kinetic kill vehicle was used to destroy a Chinese weather satellite.

A second incident happened in 2009, when two artificial satellites collided accidentally. The first was a satellite owned by Iridium Communications Inc. and the second was owned by Russian Space Forces. The Russian satellite had been out of service, but the Iridium satellite was operational. The two satellites collided at a speed of 42,120 kilometers per hour about 800 kilometers above Siberia. This collision was believed to have created 1,000 pieces of debris at least 10 centimeters in width on its own, not to mention all the many smaller ones it created.