August 10, 1972
This is Linda Baker's footage of the meteoroid.
The Great Daylight 1972 Fireball (or US19720810) is an Earth grazer meteoroid which passed within 57 km of the surface of the Earth at 20:29 UTC on August 10, 1972, or 1.01 Earth radii from the centre of the Earth. It entered the Earth's atmosphere in daylight over Utah, United States (1430 local time) and passed northwards leaving the atmosphere over Alberta, Canada. It was seen by many people, recorded on film and by space borne sensors.
By comparison, the Otto C. Winzen developed balloon reached 51.8 kilometres in 1972 and Low Earth Orbit satellites orbit from about 200 kilometres from the surface of the Earth.
Analysis of its appearance and trajectory showed it was a meteoroid about 2 to 10 metres in diameter in the Apollo asteroid class in an orbit that would make a subsequent close approach to Earth in August 1997. In 1994 Zdenek Ceplecha re-analysed the data and suggested the passage would have reduced the meteoroid's mass to about a third or half of its original mass.
The meteoroid's 100 second passage through the atmosphere reduced its velocity by about 800 metres per second and the whole encounter significantly changed its orbital inclination from 15 degrees to 8 degrees.
This was the first Earth grazing fireball observed. As of 2006 only two subsequent Earth grazers have been seen: the Earth-grazing fireball of October 13, 1990 passing at around 100 kilometres altitude over Czechoslovakia; and the possible Earth-grazing fireball on March 29, 2006 over Japan.