How scientists found Earth's new minimoon and why it won't stay here forever


Oct 22, 2019
A weird "minimoon" found circling Earth likely won't be there long.

How scientists found Earth's new minimoon and why it won't stay here forever : Read more
Interesting images and video. As the report stated "The newly identified object, now known as 2020 CD3, was very faint when it was discovered, at only about magnitude 20. (The lower the magnitude, the brighter the object.) That faintness stretches the capabilities of Catalina and is beyond what most amateurs can see in their telescopes. (Since then, the object has faded to magnitude 23, making it visible only to the largest professional telescopes.)...2020 CD3 has a "chaotic" orbit, he said, because it is pulled between the gravity of the moon and the gravity of Earth. Its distance to Earth varies between the equivalent of 0.2 and 4.5 Earth-moon distances (The average distance to the moon is roughly 239,000 miles, or 384,000 kilometers.) When Wierzchos last observed the minimoon, on Wednesday (Feb. 26), it was roughly 2.5 lunar distances away, he said. Because the object's distance to Earth varies, so does its orbital period, or the time it takes the minimoon to circle Earth. Wierzchos said the object's orbital period is difficult to measure precisely, but it seems to be about a month."

It is a very small object and very faint as reported mv+20 on the apparent magnitude scale. As comparison my 10-inch telescope can see down to about mv+14.5 in very dark skies. Over the years, radar measurements record small asteroids moving past Earth at relatively close distances too measured in lunar distances. There is a population of small objects, NEA/NEOs, these orbit farther out but can cross inside Earth location, have short lifetimes in their present orbits, commonly <=2E+6 years. The solar system features many objects that indicate youth so reconciliation with radiometric ages for the Earth and solar system based upon meteorite dating is required.



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