If you look up at the night sky right now, even if you don’t see it, you can greet the new mini moon on Earth. Why is it that we have a possible new satellite, but temporarily?
In the comings and goings of asteroids through the cosmos, our planet got an additional moon when one of those small asteroids was attracted and captured by Earth’s orbit, a few years ago, as announced by the Center for Minor Planets of the International Astronomical Union ( MPC).
On February 15, astronomers Kacper Wierzchos and Teddy Pruyne of the Catalina Sky Survey saw a strange streak of light on their screens. “GREAT NEWS,” Wierzchos tweeted this week: “Earth has a new temporarily captured object, a possible mini moon called 2020 CD3. On the night of February 15th, my Catalina Sky Survey teammate, Teddy Pruyne, and I found a magnitude 20 object. Here are the discovery images. “
What is this mini moon like?
The asteroid has been officially christened 2020 CD3 and is estimated to be between 1.88 and 3.4 meters in diameter (hence the mini-moon), about the size of a car. It is the second asteroid known to orbit Earth (the first was asteroid 2006 RH120, which was discovered in September 2006). And while it won’t last, it will act like a temporary mini-moon circling our planet. Our main satellite is no longer alone, it now has a small companion (but we should not become fond of it because it is likely that, at any moment, it will return to its regular trip, orbiting the Sun.
The small orbiting asteroid has an albedo, or surface brightness, similar to C-type asteroids, which are rich in carbon. According to orbital simulations created by astronomer Tony Dunn, 2020 CD3 has likely been circling our planet for about three years.
Why haven’t we seen it before?
Basically because most asteroids are really small, we don’t know where they are (so we don’t know where to look) and they usually don’t emit much light, even when they reflect sunlight. And even though some of them are dragged down by Earth’s gravity, they don’t stay long enough to become mini-moons. Typically, they head into the atmosphere and end up as fireballs or drift through a partial orbit before being fully captured.
The great thing about 2020 CD3 is that it is still around and offers astronomers a fabulous opportunity to investigate and explore asteroids.
Based at the University of Arizona, Tucson, the NASA-funded Catalina Sky Survey is part of the Near Earth Object Observation Program to scan the sky for potentially dangerous objects. This team of astronomers has the seemingly impossible goal of identifying and tracking 90% of all objects in our solar system that are larger than 140 meters.
And this is what our new mini moon looks like thanks to the Gemini Observatory in Hawaii that took this beautiful photo on February 24. What we see is the combination of three images with different filters that show us the mini moon and blurred colorful stars around it.
“Getting the images was a struggle for the Gemini team because the object is getting weaker and fainter as it moves away from Earth,” explains astronomer John Blakeslee of the Gemini Observatory. “It is expected to be fully ejected from Earth’s orbit in April.” And it will return to its heliocentric orbit, that is, circling the Sun.
Yes indeed. If you look at the night sky and see a bright object near the moon (from the original), make no mistake: that is not the mini moon. It is Venus , the third brightest celestial object that lights up the sky, after the sun and the moon.
Reference: Catalina Sky Survey
