There are tens of thousands of man-made objects in orbit around the Earth. Many of them are useful things, like space stations and weather satellites. However, people have left lots of unwanted objects in space too, such as parts of old rockets.These objects are known as space junk.

Since the 1950s, people have sent over 10,000 satellites into space. Many of these satellites have stopped working, but they are still in orbit because it is too expensive to bring them back to the Earth. Astronauts have also dropped things during their spacewalks, such as cameras, gloves and tool bags. These objects continue to orbit the Earth as space junk.

Space junk is a big problem, and it is getting worse. Every year, we send more and more things into orbit, and this means more and more space junk in orbit too. Most pieces of space junk are very small, but they can still be very dangerous. Objects in orbit, such as satellites and spacecrafts, are travelling very, very fast. This means a small piece of space junk can destroy a spacecraft or satellite. When this happens, the spacecraft or satellite is broken up into hundreds of pieces, and there will be even more space junk in orbit.

Scientists are very worried about space junk because it can make space missions very dangerous. If there is too much space junk in orbit, it will become impossible to travel into space. Countries around the world need to work together to solve this difficult problem.

   围绕着地球轨道上有数以万计的人造物体。很多是有用的东西，像空间站和气象卫星。然而，人们也在太空中留下了大量无用的物体，比如旧火箭的部件，这些物体被称之为太空垃圾。

   自从20世纪50年代以来，人们已经向太空发射了一万余颗卫星。许多卫星已经停止工作，但由于把它们带回地球成本太高了，所以它们仍在轨道上。宇航员在太空行走时也会掉落一些东西，比如相机、手套和工具袋。这些物体继续在地球轨道上运行，成为太空垃圾。

   太空垃圾是个大问题，而且情况越来越严重。每年，我们都向轨道发射越来越多的物体，这也意味着轨道上的太空垃圾越来越多。大多数太空垃圾都非常小，但它们仍然可能非常危险。轨道上的物体，如卫星和航天器，运行速度非常快。这意味着一小块太空垃圾就能毁坏一艘航天器或一颗卫星。当这种情况发生时，航天器或卫星会碎裂成数百块，轨道上的太空垃圾就会更多。

   科学家们非常担心太空垃圾，因为它会让太空任务变得非常危险。如果轨道上的太空垃圾太多，继续进入太空将变得不再可能。世界各国需要共同商讨来解决这个难题。