Astronomers discover an asteroid that's closer to the Sun than any other
Asteroid 2020 AV2has the smallest semi-major axis and smaller aphelion of any known asteroid.
- Zwicky Transient Facility deems this to be a
new class of asteroid.
- Its orbit falls entirely within the Earth's but does not cross the orbit of any other planet in the Solar System.
However, astronomers At the Zwicky Transient Facility ( ZTF) have discovered a new asteroid that does neither of those things.
Instead of being located in the
"Currently 2020 AV2 has both the smallest semi-major axis and smallest aphelion of any known asteroid," as per the International Asteroid Warning Network's ( IAWN) notification.
The semi-major axis is a useful way to measure how far an asteroid is from the Sun on average. If 2020 AV2 has the ‘smallest semi-major axis', this means — on average — its closer to the Sun than any other asteroid in the Solar System.
The aphelion is the point when the orbit of an asteroid is the furthest from the Sun. So if every asteroid known to man was put in a line-up of their distance from the Sun at aphelion, 2020 AV2 would be the closest to Earth's star.
It's not a threat to Earth
2020 AV2 has a diameter of between 1 to 3 kilometres — about half the height of Kilimanjaro — and it doesn't pose a threat to Earth. The Jet Propulsion Laboratory ( JPL) estimates that the 2020 AV2 will be at its closest point to the planet on 14 October 2020.
Even then, it will be nearly 0.35 AU away from Earth. That's over 11 million kilometres more than how far Venus is from the planet at its closest point.
Icaruses of the Solar System
The discovery of 2020 AV2 doesn't mean that other asteroids don't come even closer to the Sun. They do — but only for a very small fraction of their entire orbit.
However, the asteroid named after the Greek myth of the boy who flew too close to the Sun also crosses the paths of Venus and Mercury in doing so.
Since Icarus' discovery in 1968, astronomers have found other asteroids that fly even closer to the giant flaming ball of gas at the centre of our Solar System. The asteroid with smallest known perihelion — the point when the orbit of an asteroid is the closest to the Sun — is 2005 HC4.
It flies within 0.071 AU of the Sun, that's 23% closer than Mercury, but also goes out as far that 3.562 AU away from the Sun — well beyond the orbit of Mars. It may not always be the closest to the Sun, but the large divergence between its perihelion and aphelion, makes it the fastest asteroid discovered so far travelling at 565,000 kilometres per hour (kph).
In doing so, its orbit crosses the orbits of Mercury, Venus and Mars.
Only 20 asteroids spotted so far have orbits that fall entirely within Earth's dubbed Atira asteroids. And, even they cross the paths of other planets.
2020 AV2 is the only asteroid so far that orbits the Sun within Earth's, and doesn't cross any other planet's orbit.
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