PopSci attribution given to New Scientist.
“the moon may have formed from the debris of a collision between Earth and a Mars-sized body”
Complete nonsense.
I try every day but I haven’t gotten it to shake out this way yet. In fact stable near circular orbits seem relatively uncommon in this simulator.
http://www.nowykurier.com/toys/gravity/gravity.html
How can they be sure the two planets are orbiting at exactly the same distance from the sun? I know that would present an even more remarkable set of circumstances, but this universe is remarkable.
A low speed collision tears my world apart.
I love it.
But I'm gonna wait for the paperback...
The planet in front has a bumper sticker that says “I brake for asteroids!”
Pardon my confusion, but wouldn't one of the pair always be smaller?
Or did they want to mean that the smaller body always determines the orbital characteristics?
Long as they’re going the same direction...
Some of the issues with the Theia hypothesis:
The ratios of the Moon’s volatile elements are not explained by the giant impact hypothesis. If the giant impact hypothesis is correct, they must be due to some other cause.
There is no evidence that the Earth ever had a magma ocean (an implied result of the giant impact hypothesis), and it is likely there exists material which has never been processed by a magma ocean.
The iron oxide (FeO) content (13%) of the Moon, which is intermediate between Mars (18%) and the terrestrial mantle (8%), rules out most of the source of the proto-lunar material from the Earth’s mantle.
If the bulk of the proto-lunar material had come from the impactor, the Moon should be enriched in siderophilic elements, when it is actually deficient in those.
The presence of volatiles such as water trapped in lunar basalts is more difficult to explain if the impact caused a catastrophic heating event.
The Moon’s oxygen isotopic ratios are essentially identical to those of Earth. Oxygen isotopic ratios, which can be measured very precisely, yield a unique and distinct signature for each solar system body, If Theia had been a separate proto-planet, it would probably have had a different oxygen isotopic signature than Earth, as would the ejected mixed material.
These spots, known as Lagrange points, are 120 degrees in front of and behind whichever body is smaller. The discovered co-orbiting planets, located in the four-planet system KOI-730, are always 120 degrees apart, permanent fixtures in each others’ night skies.
From the link in the linked article.
http://www.newscientist.com/article/dn20160-two-planets-found-sharing-one-orbit.html?DCMP=OTC-rss&nsref=online-news
Gravitational "sweet spots" make this possible. When one body (such as a planet) orbits a much more massive body (a star), there are two Lagrange points along the planet's orbit where a third body can orbit stably. These lie 60 degrees ahead of and 60 degrees behind the smaller object. For example, groups of asteroids called Trojans lie at these points along Jupiter's orbit.
Which is it, 60 or 120 degrees? I can't finish my school project until I find out!
The L4 & L5 points are stable. The other three are not.
Garde la Foi, mes amis! Nous nous sommes les sauveurs de la République! Maintenant et Toujours!
(Keep the Faith, my friends! We are the saviors of the Republic! Now and Forever!)
LonePalm, le Républicain du verre cassé (The Broken Glass Republican)
Maybe John Norman wasn’t as crazy as we thought (nah).
Our moon is pulling away from the sun, our sun has a time predicted when it will die, earth will not last forever, so the spinning of these planets MUST be a finite point, no?
So when the finite is changed a bit, then what?
