Today, November 25, will be a busy day in the skies above our planet: Not one but two asteroids will be passing close enough to Earth to be considered a “near-Earth object” (NEO) according to NASA data.
One of the NEOs, dubbed 2018 VT7, is a smaller object of around 20 feet to 60 feet in diameter, which is fairly typical for the kind of objects that pass near to our planet. But the other NEO, known as 2009 WB105, is a monster measuring between 170 feet and 400 feet across. For reference, at its maximum calculated size the asteroid is longer than a football field and bigger than the Statue of Liberty.
The big 2009 WB105 asteroid came closest to Earth at 12:14 GMT on Sunday, November 25, or just after 7am in EST, while the smaller 2018 VT7 came closest at 17:24 GMT today, or midday EST. The smaller asteroid will come within 2 million miles of the Earth, which is fairly close in cosmological terms. Fortunately the larger object will stay at least 3.5 millions miles away so it won’t pose a risk to us here on the planet. For reference, the definition of a near-Earth object is a space body that is on an orbit path around the Sun within 120 million miles.
While big asteroids make for dramatic news headlines and good movie script fodder, NASA are more interested in the objects as artifacts of the early solar system. Because they move through space and are left relatively unchanged over long periods of time, asteroids can be studied for clues about the formation of the solar system around 4.6 billion years ago. Asteroids are usually formed of debris from dramatic events like the birth or death of stars and planets, and most of the asteroids in our solar system are remnants from the formation of the inner planets of Mercury, Venus, Earth, and Mars.
Another potential use of near-Earth asteroids is exploiting them for resources, as they can contain minerals which are difficult to find on Earth. Although it is currently not cost effective to send teams or robots to asteroids to mine them, in the future this could be a way of acquiring materials for generating rocket fuel and developing new space structures.