Soon, Earth will host a space visitor, and no, it is not an asteroid or a comet-this going to be a mini-moon. For stargazers, this rarest of astronomical events will arrive very soon, but this tiny celestial object will orbit the Earth only for a short while.
Everything you need to know about the impending mini-moon and why the scientific community is up in arms.
What Is a Mini-Moon?
A mini-moon, simply put, is an asteroid or small piece of space rock that is temporarily captured by Earth’s gravitational field, hence turning it into an orbiter for a little while. Unlike Earth’s full-time moon, which has been orbiting our planet for millions and billions of years, mini-moons are short-term visitors. They’re much smaller in size—vary from a few feet to a few meters across—and usually just remain in Earth’s orbit for a few months to a couple of years, at which point they escape again into space.
How is a mini-moon captured?
Even though the Earth’s gravity is very strong, it is not strong enough to hold a large asteroid or a space rock inside its orbit. However, when a small asteroid passes within a reasonable distance of Earth, its gravity catches the small object and keeps it within its orbit for a short period of time due to the high force. Such objects largely come from the Asteroid Belt located between Mars and Jupiter; however, sometimes a space rock drifts close enough to Earth to become a mini-moon.
The process is very much sensitive to the size of the object, the velocity, and the trajectory. A mini-moon tends to arrive without notice, and just as erratically, it departs our orbit as soon as its speed and distance from Earth change enough to break free of Earth’s gravitational attraction.
What makes this mini-moon special?
Although mini-moons had been spotted before, they are so rare. The most recent well-documented mini-moon is known as 2020 CD3, captured by Earth’s gravity in 2020 and orbiting the Earth for about three years before drifting off into the immense emptiness of space. The new mini-moon promises scientists an opportunity to study these transients and to gain insights into how the satellites of a more transient nature might impact the Earth’s gravitational field.
This mini-moon has not been named to date, and its size is estimated to be quite small although between 1 to 3 meters across in diameter. Its temporary stay will offer astronomers a rare opportunity to study the behavior, composition, and even trajectory, which could lead to insights into how such objects get stuck into Earth’s orbit in the first place.
Why Mini-Moon Stay Here for Only a Short While?
Mini-moons do not stay with us for very long because their orbits are unstable. Also, often, their orbits cross over the Earth in such a path that they make it look kind of chaotic to be along with the Earth’s orbit; and since mini-moons are so small and light, they come easily under the influence of other forces in space, like the gravity of the Sun. They end up by pulling the mini-moon away with their force, sending it back into its original orbit around the Sun or out into space.
This mini-moon will probably orbit Earth for a few months up to a year before breaking free from our gravitational hold. While we still have this guest with us, astronomers will closely observe it and extensively study the available data that this visiting object can provide them with during its short stay.
Can Mini-Moons be a threat to Earth?
One of the very first questions that would occur to your mind when you hear about a “new moon” orbiting Earth is whether it is dangerous for Earth. Luckily, mini-moons are much too small to do anything bad. If they were to enter Earth’s atmosphere, they would burn up completely, and what we would see is a harmless but impressive ball of fire in the sky.
