How much space junk is out there? Q/A from Old Farmer's Almanac Question of Day (June 18, 2014)

"Moon Question of the Day" (Wed. 18 June 2014): Question: How much space junk is out there? Answer: Tons of space junk is orbiting the Earth and sitting on the surfaces of the Moon, Venus, and Mars. The Moon alone has 20 tons of it. These are man-made items that space explorers have left behind. Since 1957, when the Russians launched the first artificial satellite, we've left our junk in the skies and on other planets--sometimes on purpose, sometimes by accident. Among this debris is a glove somebody lost on the first space walk, from Gemini 4; a camera from Gemini 10; and miscellaneous pieces of rocket boosters and spacecraft. Some of these objects will eventually fall to Earth, others will burn up as they enter Earth's atmosphere, and still others will remain in space for many, many years. [www.almanac.com]