How Far Away is the Nearest Asteroid from Earth?

The distance to the nearest asteroid can vary significantly and is typically determined by the specific asteroid involved and the current time. The closest known asteroid to Earth as of now is 2020 CD3, a temporarily captured object discovered in February 2020. 2020 CD3 orbits Earth and usually remains within a few thousand kilometers to tens of thousands of kilometers from our planet.

Many asteroids pass close to Earth, with some coming within a few million kilometers, which is still considered close in astronomical terms. Near-Earth Objects (NEOs) often approach Earth at varying distances. If you're interested in a specific asteroid or a particular time frame, feel free to let me know!

The Greatest Distance of a Known Asteroid from Earth

We can reasonably assume that not all asteroids have been discovered, so we cannot conclusively answer the question about the farthest an asteroid has ever been from Earth. The greatest distance of a known asteroid from Earth is reported to be that of the asteroid '2012 UP113', which reaches a maximum distance of 80.4 astronomical units (AU). This is just over eighty times the average distance from Earth to the Sun.

The Furthest an Asteroid Has Ever Been from Earth

The furthest an asteroid has ever been from Earth is difficult to determine, as asteroids can have highly elliptical orbits that bring them close to and far from the Earth. However, the asteroid 2018 VG18, also known as Far-out, is currently considered the most distant object in the solar system. Its aphelion (farthest distance from the sun) is 175.51 astronomical units (AU), which is over 26 billion kilometers or 16 billion miles away from Earth.

Proximate Asteroids and Our Atmosphere

While searching for the nearest asteroids, it's worth noting that small asteroids can enter Earth's atmosphere quite frequently. It's possible for one to be under a meter in size to enter Earth's atmosphere even as you are reading this. Earth regularly scoops up tons of asteroid material daily, contributing to the cosmic dust layer we find in our atmosphere.

Near-Earth Asteroids

A near-Earth asteroid is defined as an asteroid whose perihelion is less than 1.3 Astronomical Units (AU). This category includes asteroids that do not actually cross Earth's orbit at aphelion (farthest point from the Sun) at 1.017 AU. The concept of this arbitrary perihelion distance reflects the potential for future orbital disturbances, such as collisions or near passages to Mars, or by an asteroid of sufficient mass that could alter its orbit into an Earth-crossing one.