The NASA Orbital Debris Program Office at the Johnson Space Center released this video on October 28, 2014. The animation shows the orbits of the known debris 10 cm or larger. The database includes over 21,000 objects in that size range. There is more information below the video.
Three views are illustrated with these frames from the animation. Images courtesy of NASA.
LEO | Low Earth Orbit
The vast majority of orbiting debris is within 2000 km of the surface of the Earth. The dots in the image below show the location of each piece of debris being tracked. The orbital debris dots are scaled larger than actual size to increase their visibility. They are not scaled accurately to the size of the Earth. The images show clearly where the most orbital debris exists.
It is estimated there are more than 500,000 particles between 1 and 10 cm in diameter. Their may be as many as 100 million smaller than 1 cm. These smaller sized particles of debris are not tracked or illustrated in this model.
GEO | Geosynchronous Earth Orbit
Taking a more distant view in the animation, we see a distinct ring of objects. The left viewpoint is obliquely above the plane of the equator. The right viewpoint is from above the north pole. The distance out to the ring of objects is a little more than 6 Earth radii. Objects near the Earth must travel very fast to remain in orbit. Farther away, they can go slower and remain in orbit. At the distance of the ring, the orbital speed is such that it takes 24 hours to complete each orbit. That is the same time as one rotation of the Earth. These objects appear to be over the same location due to that synchronization. Hence, we call them geosynchronous orbits.
The Office has a list of FAQ.
1. Debris are man-made objects in orbit than serve no purpose.
2. Dead spacecraft, stages of launch vehicles, pieces released during spacecraft separation or during a mission, result of explosions or collisions, flecks of paint, etc, to name a few sources.
7. Orbital debris nearest the Earth travel speeds of 7 to 8 km/s. A small piece of debris involves much energy.
8. The International Space Station will have its orbit adjusted if the odds of a collision with debris are as high as 1 in 10,000. This happens about once a year.
12. The higher the orbit, the longer the debris stays in orbit. Debris below 600 km normally returns to Earth within a few years. At 800 km, it may stay up for decades. Above 1,000 km, it could continue for a century or more.
13. Over the past 50 years, a tracked piece of debris fell back to Earth each day with no serious injury or significant property damage yet confirmed.