NASA Spacecraft Discovers Tiny Moon Around Asteroid (apnews.com) 18
During a close flyby of the asteroid Dinkinesh, NASA's Lucy spacecraft discovered a mini moon a mere one-tenth-of-a-mile (220 meters) in size. For comparison, Dinkinesh is barely a half-mile (790 meters) across. The Associated Press reports: NASA sent Lucy past Dinkinesh as a rehearsal for the bigger, more mysterious asteroids out near Jupiter. Launched in 2021, the spacecraft will reach the first of these so-called Trojan asteroids in 2027 and explore them for at least six years. The original target list of seven asteroids now stands at 11. Dinkinesh means "you are marvelous" in the Amharic language of Ethiopia. It's also the Amharic name for Lucy, the 3.2 million-year-old remains of a human ancestor found in Ethiopia in the 1970s, for which the spacecraft is named.
And they're going to call it... (Score:2)
( Not my joke )
Re:And they're going to call it... (Score:4, Funny)
A news site providing the original measurements (Score:2)
Shock-horror, the sky is falling!
Been a nice surprise how common doubles are. (Score:3)
Nothing new about moons of asteroids (Score:4, Insightful)
There is nothing new about moons of asteroids. Their existence had been predicted by Tom Van Flandern, who advanced an "exploding planet" explanation for the orbits of comets. Early confirmation of moons of asteroids from lunar occultation observations was regarded as sketchy, but hard confirmation (of asteroids having moons, not exploding planets) came later from spacecraft fly by photos.
I read Van Flandern's Dark Matter, Missing Planets, Missing Comets. Interestingly, the Astronomy library here at the U has a copy, but the book is replete with fringe science that had resulted in Van Flandern being "separated" from his position at the US Naval Observatory.
To my reading of this book, Van Flandern had good explanations of what is possible and what is if possible highly unlikely in orbital mechanics, especially mechanisms by which asteroids might be captured as moons by planets. The moons of Mars as well as the smaller moons of Jupiter are hypothesized to be captured asteroids, but capture of an isolated asteroid from the standpoint of orbital mechanics is an exceedingly unlikely event. Much more likely is the capture of an asteroid from a small swarm of asteroids, maybe even a binary pair of asteroids, where the encounter of multiple bodies with the gravitational field of a planet can result in one of the bodies being captured and the remaining bodies being flung away, accounting for where all the angular momentum went. Or at least that is my short summary, otherwise, one can read his book.
There are a number of mysteries about the Solar System, including how asteroid-like bodies can be captured as moons, let along enter nearly circular orbits around a planet, the unstable orbit of Phobos that will crash it into Mars in a 100 million years, the retrograde orbit of a moon of Neptune, the more-than-90 deg inclination of the rotation axis of Uranus along with the orbital plane of its moons, the stable Neptune-crossing orbing of Pluto, the Oort Cloud comets where it is unlikely that they formed out in that sparse expanse and others. Van Flandern even questions the accretion of planets from asteroidal bodies in the early Solar System because of the tendency of bodies in similar, circular orbits to encounter each other with a square-dance do-si-so rather than smash into each other.
Now mainstream science has been chipping away at least some of these questions with a hypothesis that the "planetoids" from which the planets accreted before the Solar nebula fully dissipated. The combination of gravity and gas dynamics allowed considerable migration of the orbits of even large Jupiter-sized bodies, so where an object is right now doesn't have to be where it formed. A lot of this science has been driven by the discovery of the "hot Jupiters" orbiting close to other stars.
Now you can pick apart my summary of what I call unanswered questions about the Solar System, but one can read Van Flandern's book to find out what concerns he raised and debunk them directly rather than my paraphrasing. What I am trying to say is that his work appears to start on a scientific foundation, especially on what was known at the time before the discovery of the "hot Jupiter" exoplanets and the resulting advances in theories of planetary formation to explain them. From there, Van Flandern dives deeper and deeper into pseuo-scientific speculation.
He offers an interesting observation that the orbits of comets show an "explosion signature" seen in the debris of exploded upper stage rockets in Earth orbit. In his role at the Naval Observatory, he probably knew a lot about the orbits of fragments of upper-stage rockets. It is the business of Naval Observatory and other government agencies to know about the hazards to crewed and un-crewed spacecraft from "space junk." So if he wrote that the comet orbits show an "explosion signature", I will go with that he knew what he was talking about.
But it is a leap from this explosion signature to claim this proof of a very implausible event, na
Re: Nothing new about moons of asteroids (Score:2)
Is Wegener's story sad because of him, or the pompous reaction of the scientific establishment to him?
Re: (Score:3)
Wegener's story is also sad because he died on an expedition before his theory being vindicated.
In terms of the parallels to Van Flandern, Wegener also advocated a theory in the absence, at the time, of a plausible physical basis. Van Flandern's exploding gas-giant planet, however, seems much more remote from vindication than Wegener's drifting continents.
What is sad, to me, about Van Flandern's life is that if he had left things the way Wegener did, here are the trajectories that fit an explosion pro
Re: Nothing new about moons of asteroids (Score:2)
What if the current scientific consensus is as Bozo-the-clowny as epicycle theory, or the theory that what you can't see can't hurt you (which is why President Garfield's doctor refused to wash his hands before operating), or the more recent pronouncement that Covid-19 was not airborne?
Regarding mechanisms, why did geologists refuse to entertain continental drift because it had no physical mechanism, while physicists have accepted dark matter and dark energy without requiring a mechanism?
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In 1974, I found myself "sitting on the dock of the channel" on Catalina Island during "Frosh Camp" when a genial man wearing a bola or shoestring tie walks up to me. For some reason, geologists are required to wear this type of tie. He introduced himself as Gene Shoemaker, and he proceeded to explain how the rock I was sitting on was once part of Long Beach, CA, got shoved underground and came up on the other side of the channel.
Here I was, Gene Shoemaker was telling me all about plate tectonics, and
That's no moon (Score:2)
Its a space station
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Its a space station
I came here for this comment.
Re: That's no moon (Score:1)
This is cool (Score:2)
It sounds like this would be really cool to see in person.
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Isaac Newton would be delighted ... but not surprised.
The rock is trying to take a shit (Score:1)
...give it some privacy.