Could Mercury have been a Moon in Past ?

[AztecastroMcJ]

ok here goes

i realise Mercury is orbiting Sun but am wondering if in its past it was possibly Moon of say planet Venus

reasons for thinking this

mainly due to how similar it seems to our Moon in apperance n size

also Mercury and Venus don't have any Moons yet all other planets in our solar system do

Mars has very small Moons in comparison to others but Mars is also much smaller planet

hence my reason for thinking Mercury may have been Moon of Venus in past-

also they're very close to each other,

think that Mercury if it was Moon of Venus was possibly hit by some impact to send towards Sun's Orbit

Could Mercury have been Venus's Moon ?

Has Venus ever had Moon in Past ? (if not why not?)

also when viewing Jupiter and its 4 Main Moons my 1st thought was they were linked to banding detail on planet

if the Earths Moon effects Tides, what effect do Jupiters Moons have on it ?

what would effect be if Earth had more than one Moon ?

say 4 Moons like Jupiters ?

Any comments appreciated

(Pic is Mercury)

James

[brianb]

If so you have to explain how it got free.

Mercury & the Earth's Moon may appear superficially very similar, but Mercury is so heavy it must have a massive iron/nickel core whereas the Moon is deficient in the "heavy metals". Assuming that the origin of the Moon is by impact of the Earth with another protoplanet, the lunar deficiency is understandable as it would be made material which was once part of Erth's mantle; whereas Mercury would be much more likely to always have been king of its own zone of the solar system.

[brianb]

if the Earths Moon effects Tides, what effect do Jupiters Moons have on it ?

Not much, Jupiter is far too massive to be much affected by tiddlers like his moons. The tides Jupiter causes on the moons, and which the moons raise on each other, do however have profound effects, e.g. the vulcanism on Io.

what would effect be if Earth had more than one Moon ?

say 4 Moons like Jupiters ?

They'd have to be small ones, more than one the size of the one we have would be incredibly unliklely to form an orbital system which would be stable over centuries, let alone thousands of millions of years. Even if say 500 miles in diameter they'd be active bodies because of tidal heating; the tide tables would be incredibly complex, and astronomers wanting dark skies would be far less happy bunnies even than they are at present.

[AztecastroMcJ]

Not much, Jupiter is far too massive to be much affected by tiddlers like his moons. The tides Jupiter causes on the moons, and which the moons raise on each other, do however have profound effects, e.g. the vulcanism on Io.

They'd have to be small ones, more than one the size of the one we have would be incredibly unliklely to form an orbital system which would be stable over centuries, let alone thousands of millions of years. Even if say 500 miles in diameter they'd be active bodies because of tidal heating; the tide tables would be incredibly complex, and astronomers wanting dark skies would be far less happy bunnies even than they are at present.

think that 'moon' astronomers would b very happy tho having 4 moons to view

not sure i agree with the Moon Earth Impact theory

think something must have hit mercury out of Venus's orbit which sent it towards and into its own current orbit

thanks for ur points tho cleared few things up on mysteries of Moons

do u think its strange Venus doesn't have Moon?

[gman]

It would take one heck of a lot of energy to knock something the size of Mercury from a Venus orbit to one around the sun. Easily enough to destroy both bodies concerened.

[AztecastroMcJ]

understand ur points on such a large impact would destroy both bodies,

Mercury does have two of the largest named impact craters out of top 5 largest, in our Solar System

funnily enough others in top 5 are Mars n our Moon(Mercury,Mars,Moon)

MMM..........

[George]

think that 'moon' astronomers would b very happy tho having 4 moons to view

DSO imagers would be tearing their hair out

[MeerkatinBKK]

Mercury does have two of the largest named impact craters out of top 5 largest, in our Solar System

funnily enough others in top 5 are Mars n our Moon(Mercury,Mars,Moon)

MMM..........

But these are bodies upon which we can see craters. Venus and the gas giants have such thick atmospheres that we can't, so your theory based upon named craters doesn't really hold any water. Even on Earth, tectonic shifts have hidden what would have been huge holes in the ground (and don't forget water too).

Still, an interesting posit all the same . Personally I'd love to know how people here think the moon ends up, given that it's slowly drifting away from us. Could it be caught by Venus? How will the earth (particularly its life) be affected by being moonless?

Nick

Edited to add: Before a Daily Mail journo reads this and then reports that the moon is deserting us, er, it won't happen for a "while".

[vhbelvadi]

If so you have to explain how it got free.Mercury & the Earth's Moon may appear superficially very similar, but Mercury is so heavy it must have a massive iron/nickel core whereas the Moon is deficient in the "heavy metals". Assuming that the origin of the Moon is by impact of the Earth with another protoplanet, the lunar deficiency is understandable as it would be made material which was once part of Erth's mantle; whereas Mercury would be much more likely to always have been king of its own zone of the solar system.

Let's say Mercury had been the natural satellite of the Earth, itself. Then, the impact of an object - if it was sufficuent enough - could have pushed Mercury away. This object may then have become our moon.

Also, this means Venus might have once been our moon too.

The mass of Mercury is ~0.3X(10)power24, Venus is ~4.8X(10)power24, and Moon is ~7.36X(10)power22; which means that the mass of the protoplanet (of which the moon was a part) must have been far greater. Great enough to push Mercury and Venus - which had, by now, accumulated enough of their Iron and Ni-Fe cores (respectively) in parallel to the Earth - away.

_ _ _

It would take one heck of a lot of energy to knock something the size of Mercury from a Venus orbit to one around the sun. Easily enough to destroy both bodies concerened.

Right you are!

_ _ _

understand ur points on such a large impact would destroy both bodies,

Mercury does have two of the largest named impact craters out of top 5 largest, in our Solar System

funnily enough others in top 5 are Mars n our Moon(Mercury,Mars,Moon)

MMM..........

Guess you can explain that those craters are the result of the phenomenon I've explained in my reply to brianb (see the top of this reply).

Satisfying?

[Sparrow]

From what I've seen, early in our solar system the surplus debris gradually clumped to form many planets/planetoids - far more than there are today. They would have all been continually reacting with each other's orbit and it would have all been far more chaotic than it is now. Planet's would have been colliding, blowing each other apart, amalgamating, and trapping smaller bodies in to "moon" orbits. Our very own Earth and Moon set up fits in to this theory very nicely. It's easy to forget that the planets continue to evolve and grow on a daily basis as they collect more debris (meteors). I think it's quite feasable that Mercury might once have been a satellite of Venus, but with its density, Venus just couldn't hold on to it and the pull from the Sun pulled it out of orbit until it settled in its own orbit around the Sun.

The latest theory I heard recently is that Saturn and Jupiter's orbit were once the other way round. I can't remember the reasoning why it changed but apparently Saturns orbit continues to grow away from Jupiter.

As for the question of what the Earth would be like after the moon escapes its orbit - I gather that the moon is a stabalising influence on the Earths axial tilt which keeps out rotation steady and gives us the seasons. Without this, the tilt could become very unstable leading to chaos in the seasons and an environment far less friendly to life - particularly human life.

One other influence of the moon which fascinated me when I first heard about it was how it is slowing the Earth's rotation - whilst the Earth's orbit round the Sun has remained stable, and therefore the length of the year is stable, on the other hand, its rotation on its own axis is gradually slowing leading to longer days, and fewer of them per year. The proof for this apparently comes from studying ancient fossilised stromatolites - thanks to their tendency to build up in the direction of the sun, and the sun's position near the equater moving from north to south, they can count the layers in the stromatolites each year and make estimated guesses as to how many days the were - I've seen figures of 500+ days a billion years ago with days lasting about 17 hours. I think this is still a controversial area and there is some disagreement over the figures but there appears to be a broad agreement that there were more days and they were shorter.