The Intervenusian Asteroid '2020 AV2' Is the First of Its Kind – And Now the Second-Closest Object to the Sun
The very first "intervenusian" asteroid has been confirmed, according to reports from Live Science and The Virtual Telescope Project. Asteroid 2020 AV2 is the only known asteroid that circles the Sun completely within the bounds of Venus' orbit.
Astronomers first spotted the asteroid on January 4, 2020, with the Oschin Schmidt telescope at the Zwicky Transient Facility in California. Then, on January 8, Gianluca Masi of The Virtual Telescope Project used a robotic telescope to photograph the asteroid low in the sky on a clear night near Ceccano, Italy.
Here's what we know about asteroid 2020 AV2 so far:
It has the second-smallest aphelion (distance from the Sun) of any object in our solar system, which makes it the second-closest object to our Sun after the planet Mercury. This also means that it has the shortest orbit of any known asteroid, lapping the Sun in just 151 days. Scientists think that it's a few miles across in diameter, but nobody knows for sure: Despite having images of the asteroid, we're still struggling to get a clear look at it.
The reason, according to Phil "Bad Astronomer" Plait, is because asteroids that circle the Sun within Earth's orbit are notoriously difficult to spot. (2020 AV2 moves completely within Venus' orbit, so it falls within that category.) From our perspective on Earth, they're always close to the Sun; you can only spot them at twilight. Atmospheric conditions can also muddy the image quality, especially so low on the horizon. Fewer than 24 of these asteroids are known to exist as a result – but, clearly, there could be many more. An experienced stargazer with a good telescope and camera of their own can catch a glimpse of 2020 AV2 with a bit of luck and planning. You can calculate the ideal coordinates for your address at the NASA JPL Near-Earth Object Small-Body Database Browser.
Astronomers are also working to find asteroids whizzing between the Sun and Mercury, which will be even more difficult to spot for the same reason – perhaps that's something the Parker Solar Probe might be suited to help shed some light on.