Earth grabbed its second minimoon this year that was orbiting the planet for 2.7 years and now, scientists have revealed intricate details of the cosmic visitor.
Using data collected with the Lowell Discovery Telescope, astronomers determined 2020 CDE, or CD3, is nearly five feet in diameter – about the size of a car – and came within 8,100 miles of Earth at its closest approach.
The team studied CD3's changing brightness, allowing them to see its rotation rate was about three minutes.
These observations helped clarify that the object was indeed an asteroid and not a relic of human-made space junk, as another object that was found to just months ago.
Grigori Fedorets of Queen's University Belfast said: 'The rotation rate was probably the largest unanswered question of this research. The Lowell team showed that it rotates slower than anticipated for objects of this size range.'
2020 CD3 was spotted in February by the NASA-funded Catalina Sky Survey.
However, initial observations estimate it to be much larger – experts said it was up to 12 feet in diameter.
The minimoon was seen on February 15 by astronomers Kacper Wierzchos and Teddy Pruyne and then again the team saw it four more times two days later – this was enough evidence to announced Earth had a new visitor.
'BIG NEWS. Earth has a new temporarily captured object/Possible mini-moon called 2020 CD3. On the night of Feb. 15, my Catalina Sky Survey teammate Teddy Pruyne and I found a 20th magnitude object,' Wierzchos shared in a tweet on February 25th, after the Minor Planet Center, a branch of the International Astronomical Union classified the asteroid as a temporarily captured object.
Now, a new study reveals more details of the minimoon that has since traveled back into space - it left in March.
Lowell Observatory astronomer Nick Moskovitz and former Lowell postdoctoral fellow/current Arecibo Observatory scientist Maxime Devogele participated in the effort, assisted in observing on the Lowell Discovery Telescope (LDT) by the University of Maryland's Quanzhi Ye.
Astronomers used the Large Monolithic Imager on the LDT to observe CD3's rotation, which revealed a number of characteristics of the asteroid.
'Observing objects this small is challenging and requires a telescope big enough to see them. In addition, their transient nature means the window of time to observe them can close quickly, the team shared in a statement.
However, LDT is designed for such events.
'This object wasn't bright enough to study for very long,' said Moskovitz.
'The fact that we have this telescope in our backyard and were able to rapidly respond really made a difference.'
Although minimoons are rare, the team predicts more to appear over the next decade.
According to Fedorets, 'Minimoons are expected to be discovered in high numbers in the following decade, with the opening of the Vera C. Rubin Observatory expected in 2023.'
The first minimoon was discovered in 2006 and astronomers believed there would be a third this year when the spotted an object with an incoming trajectory towards Earth.
Dubbed 2020 SO, the entity has been on an Earth-like orbit for more than a year and is set to become trapped in our planet's gravity starting in October and stay until May 2021.
However, it was later determined to be a discarded part of the Surveyor 2 Centaur rocket that launched in 1966.
This article has been adapted from its original source.
© Associated Newspapers Ltd.