In the visualization above, each of the white dots is a piece of orbital garbage in Low Earth Orbit (1,240 miles above the planet) that NASA is currently tracking. ScienceNews posted an article about "the largest junkyard in the solar system," explaining how the trash is monitored and why it can be incredibly dangerous. The feature is in their "For Kids" section but I found it quite informative myself. From ScienceNews:
There are some unusual things up there, like a camera that floated away from astronaut Sunita "Suni" Williams in December 2006. Other astronauts have lost tools like wrenches and screwdrivers. In 1965 astronaut Ed White even lost a spare glove. Most of the junk, however, comes from large satellites and rockets that fell apart after they stopped working.
Together, all the space junk would weigh about 11 million pounds on Earth, or more than 3,000 cars. The largest piece is a part of a rocket about the size of a minivan. The smallest piece would fit on your pinkie fingernail with room to spare…
Space junk races around the Earth at breakneck speeds. Most pieces fly through space at more than 20 times the speed that sound travels on Earth. Going that fast, even the smallest pieces mean big trouble for spacecraft. For example, a tiny marble in orbit around the Earth can have as much energy as a bowling ball going 500 miles per hour, or a car going 30 miles per hour.
"The Solar System's Biggest Junkyard" (ScienceNews)