The National Space Agency (NASA) has found a small asteroid that has been sticking around our planet for about 100 years. It’s called Asteroid 2016 HO3 but scientists have nicknamed it Earth’s mini moon because it plays around our orbit while moving relative to the sun. The rock, whose size is 120-300 feet, is also considered a quasi-satellite and was first observed by the Pan-STARRS 1 asteroid survey telescope in Hawaii last April 27.
The telescope that allowed scientists spot the mini-moon for the first time is operated by the University of Hawaii’s Institute for Astronomy and funded by the Planetary Defense Coordination Office, a NASA department tasked with monitoring near-Earth objects.
There’s nothing to worry since the asteroid is stable and represents no threat to Earth. It is not considered an actual satellite because it’s too far from our world and the closest it’s ever been to us is comparable to 38 times the distance of the moon. Still, NASA researchers like to say it’s like a mini-moon because Earth’s gravity keeps tugging at it, preventing it from wandering astray.
Paul Chodas, manager of NASA’s Center for Near-Earth Object (NEO) Studies at the Jet Propulsion Laboratory in Pasadena, California, explained that the rock’s loops around Earth tend to drift forward or backward from year to year, but our planet’s gravity is so strong that it reverses the drift when the asteroid is getting too far. In fact, the strength of Earth’s gravity doesn’t allow it to wander farther away than 100 times the distance of our actual moon.
“The same effect also prevents the asteroid from approaching much closer than about 38 times the distance of the moon. In effect, this small asteroid is caught in a little dance with Earth,” Choda added, according to the Jet Propulsion Laboratory’s website.
Asteroid 2016 HO3 takes about a year to orbit the Earth and it spends around a semester ahead of our planet before it suddenly moves to tail it for the remaining months. The object has been doing that for decades, sometimes positioning itself in front of the Earth and closer to the sun and other times approaching the earth as it jumps behind it.
NASA researchers said the asteroid’s orbit is tilted a little and that its “game of leap and frog with Earth” will most certainly last for more centuries.
Not the first asteroid that becomes trapped in Earth’s gravity
Thirteen years ago, asteroid 2003 YN107 experienced a similar dance as it became trapped in Earth’s orbit, but it followed the orbital pattern for a much shorter period of time than HO3. It eventually broke free and left our vicinity.
Another near-Earth object that has been considered as a quasi-orbital satellite of Earth is 3753 Cruithne, discovered in 1997, according to a report by Discover Magazine. It is not an actual satellite because it doesn’t loop around us in a nice ellipse way as the moon and the man-made satellites launched into orbit.
Cruithne is still around the Earth, but it takes about 800 years to complete its unstable ring shape around our orbit, which means that Asteroid 2016 HO3 is once again more significant given that it goes through the same process in just about a year.
A full list of recent and upcoming close approaches are available on the website of the Center for NEO Studies. The public can take a look at other information regarding different NEOs that have been discovered so far.
Source: NASA’s Jet Propulsion Laboratory