The meteor that exploded over the steppes of southwestern Russia sent a low-frequency rumble bouncing through the Earth , giving scientists new clues about the biggest cosmic intruder in a century . The big boom over Chelyabinsk on February 15 also produced a wave of sound thousands of times lower than a piano 's middle C -- far below the range of human hearing , according to the international agency that watches for nuclear bomb tests . The Comprehensive Test Ban Treaty Organization said that sound wave showed up on sensors from Greenland to Antarctica , making it the largest ever detected by its network . Scientists then used that wave to calculate the size of the small asteroid that plunged to Earth , said Margaret Campbell-Brown , an astronomer at Canada 's University of Western Ontario . The duration of the wave -- about 32 seconds -- let scientists estimate the energy of the blast at between 450 and 500 kilotons , the size of about 30 early nuclear bombs . From there , Brown said , they could calculate the size of the fireball ; and using an estimate of the meteor 's speed from the numerous dashboard and mobile-phone cameras that captured the scene , it was `` first-year physics '' to figure out the approximate size and weight , she said . The latest estimate is that the Chelyabinsk meteor was about 56 feet ( 17 meters ) across , weighed more than 7,000 tons and was moving about 18 kilometers per second ( 40,000 mph ) when it blew apart , she said . Opinion : A meteor and asteroid : 1 in 100 million odds . `` In terms of things we have observed , this is the largest since Tunguska , '' Brown said , referring to the suspected meteor that flattened a Siberian forest in 1908 . The nuclear test monitors pick up `` infrasound '' , or low frequency , waves from about 20 meteors a year -- `` if conditions are right , perhaps as small as a pea , '' she said . Russian authorities say more than 1,500 people were hurt , mostly by flying glass , when the Chelyabinsk meteor exploded in spectacular fashion . Amateur video footage showed a bright white streak moving rapidly across the sky before exploding with an even brighter flash and a deafening bang . Bill Cooke , head of NASA 's Meteoroid Environment Office , said scientists believe the object originated in the asteroid belt between Mars and Jupiter . It was the Apollo group of asteroids , which circle the sun in oblong orbits , that occasionally cross Earth 's . Cooke said scientists expect to study the Chelyabinsk event for months . But the dozens of fragments that have been found so far point to a fairly common , stony asteroid with traces of nickel and iron . `` The composition is not at all unusual as far as meteorites go , '' he said . `` It was just very big . '' More space and science news on CNN 's Light Years blog .
Nuclear test sensors picked up meteor 's sound wave as far away as Antarctica . Scientists used that sound to calculate the size of the space rock . Comment: