Image courtecy of NASA/Goddard/SwRI/Johns Hopkins APL/NOIRLab
Joel Kontinen
Researchers have proposed a model for how a double moon named Selam formed around the tiny asteroid Dinkinesh. This is the first 'contact binary' moon ever discovered, scientists say.
“When NASA's Lucy
mission flew past the asteroid Dinkinesh on Nov. 1, 2023, it discovered an
unexpected companion: a pair of fused moons that scientists named Selam. Now,
researchers have proposed a model explaining how Selam may have formed.”
It seems that
space is more wonderful than we thought.
“Astronomers supervising Lucy ― a car-sized spacecraft that launched on Oct. 16, 2021 ― had
primarily intended to study Jupiter's Trojan asteroids, two swarms of
space rocks that lead and lag behind the gas giant as it careens around the
sun. However, in January 2023, they added the diminutive main-belt asteroid
Dinkinesh — affectionately called "Dinky" — to the spacecraft's
travel itinerary as its first destination. This flyby was supposed to be a
dress rehearsal, allowing Lucy's team to test a system for tracking and imaging
asteroids.
As Lucy approached
Dinky, astronomers saw signs that the small asteroid was orbited by an even
smaller moon. But when Lucy swooshed past — ultimately coming within 430
kilometres or 267 miles of the asteroid while snapping hundreds of
high-definition photos — the researchers saw the truth was even stranger than
they predicted. The images revealed that Selam wasn't one, but two
"moonlets" touching each other as they orbited Dinkinesh. “
Source:
Deepa Jain 2024 'Dinky' asteroid imaged by NASA has
ultra-rare double moon, study confirms | Live Science 30 May.