Neptune may have eaten a planet and stolen its moon

New Scientist ^ | March 22, 2010 | David Shiga

[SunkenCiv]

Neptune's own existence was a puzzle until recently. The dusty cloud that gave birth to the planets probably thinned out further from the sun. With building material so scarce, it is hard to understand how Uranus and Neptune, the two outermost planets, managed to get so big.

But what if they formed closer in? In 2005, a team of scientists proposed that the giant planets shifted positions in an early upheaval (New Scientist, 25 November 2006, p 40). In this scenario, Uranus and Neptune formed much closer to the sun and migrated outwards, possibly swapping places in the process.

That would have left behind enough material just beyond their birthplace to form a planet with twice the Earth's mass, according to calculations published in 2008 by Steven Desch of Arizona State University in Tempe.

Neptune's peculiar moon Triton may once have been paired with this hypothetical super-Earth, Desch and colleague Simon Porter now say. Triton is larger than Pluto, and it moves through its orbit in the opposite direction to Neptune's rotation, suggesting that it did not form there but was captured instead.

For Neptune to capture Triton, the moon would have had to slow down drastically. One way to do this is for Triton to have had a partner that carried away most of the pair's kinetic energy after an encounter with Neptune. In 2006 researchers argued that Triton was initially paired with another object of similar size that wound up being gravitationally slung into space after the pair ventured near Neptune (New Scientist, 13 May 2006, p 8).

[SunkenCiv]

• NASA Finds Another Solar System Mystery based on Stardust mission
• Large moon of Uranus may explain odd tilt

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[John-Irish]

Triton rotates counter-clockwise as a result of it ‘’drifting’’ into Neptunes orbit.

[Talisker]

[DannyTN]

I hate when that happens.

[mlocher]

Speaking of Neptune, thanks for the picture of Uranus.

[kimmie7]

Bad Neptune! Bad!

Did you rub its nose in it?

[imjimbo]

Hillary is scummier than we realize-!

[Talisker]

Speaking of Neptune, thanks for the picture of Uranus.

Not mine... ours...

[neverdem]

Thanks SunkenCiv

[SunkenCiv]

Isn’t that Pluto? ;’)

[SunkenCiv]

Thanks John-Irish.

[SunkenCiv]

My pleasure.

[screaming eagle2]

ok

[kimmie7]

lol

[Lucius Cornelius Sulla]

Sounds like billiards.

[Zeppo]

Neptune may have eaten a planet...

I'm getting hungry just reading about it...

[John-Irish]

I saw Neptune once, years ago through a very powerful scope. Faint as it was it was a beautiful Robins -egg blue.

[PIF]

Then again some have postulated that the solar system until recently was radically different from what we see today - Earth, Mars and Venus being moons of Saturn...

[SunkenCiv]

That should get the party started. :’)