This autumn, according to scientists, planet Earth has temporarily gained a second ‘moon’. Whilst it won’t be around for long, Earth’s gravitational pull has attracted a small asteroid into its orbit, making it a second moon for a couple of months from the end of September. Unfortunately, due to its small dimensions, it won’t be visible to the naked eye and will only be able to be seen with a professional telescope.
NASA first spotted this asteroid on the 7th of August using its Alert System (ATLAS) and its trajectory was studied by scientists of the American Astronomical Society. According to these scientists, if an asteroid of this size is moving slow enough, at a speed of around 2,200mph, then our planet’s gravitational field can pull it in and temporarily trap it, making it enter our orbit. The asteroid is predicted to be about 32ft long, which is considerably smaller than the size of Earth’s moon.
Asteroids range in size, with the largest one being Vesta, which is 329 miles in diameter. It is then understandable why the ‘mini moon’ that has entered into our orbit is not visible to the naked eye. Asteroids are usually irregularly shaped bits of rock that revolve around the Sun in an elliptical orbit.
As they revolve in these elliptical orbits, the asteroids will rotate, gaining speed as they go, sometimes moving erratically. Scientists predict that it will spend about two months orbiting Earth, beginning from the 29th of September and leaving around the 25th of November. Due to the short amount of time that it will be in the Earth’s gravitational field, it will not complete a full revolution of Earth.
According to NASA, the majority of asteroids orbit the sun between Mars and Jupiter, in the asteroid belt, as both have a very strong gravitational pull. However, there are occasions where asteroids get pulled away from the asteroid belt and into Earth’s neighbourhood by the gravitational pull of planets nearby to Earth. This doesn’t happen that often, and it is even less common for an asteroid to enter completely into our orbit, creating a second moon for Earth.
This isn’t the first time that this has happened, with ‘mini-moons’ being spotted in the past, and NASA scientists predict that many, even smaller ‘mini-moons’ will have never been spotted. These ‘mini moons’ will sometimes re-enter Earth’s orbit, and scientists are predicting that this asteroid will return to orbit the Earth again in 2055. Keep an eye out for pictures of this ‘mini moon’.