PDA

View Full Version : If Earth were the only planet



laurele
2007-Nov-09, 02:18 AM
in the solar system (and would still have our Moon), would that affect its ability to produce life, its seasons and weather, etc. in any way or would there be absolutely no difference in conditions here if Earth were the only planet to orbit the Sun?

Jens
2007-Nov-09, 02:44 AM
I'm fairly sure that it would have basically no effect. Except that a lot of astrologers would go out of business!

Neverfly
2007-Nov-09, 02:45 AM
This question sent my mind reeling.
The implications are a bit tougher than just the gravitational effects of the other planets.

Mostly I would say that there wouldn't be any major differences...

However, current theory suggests that our moon was made from an impactor that seperated it fom Earth long ago.

Also- the formation of the solar system includes all the gravity wells created by all the planets- I wonder if the Earth would be in an entirly different orbit- Had the formation of the solar system included them- or not.:neutral:

ETA: Without Jupiters gravity tug on a comet throughout the eons- maybe a near miss comet would have struck- :p

Captain Kidd
2007-Nov-09, 02:56 AM
ETA: Without Jupiters gravity tug on a comet throughout the eons- maybe a near miss comet would have struck- :pOr not have struck.

Neverfly
2007-Nov-09, 02:57 AM
Or not have struck.

I think it struck my head...:doh: It hurts now...

Ronald Brak
2007-Nov-09, 03:24 AM
Assuming earth could form the same as it is now, I'd say no real change. The Malkovitch cycles (small changes in earth's orbit and tilt that can affect climate to a limited degree, but which can trigger shifts to different climate equilbriums) would be kind of boring.

Jupiter might protect us from some comets, but it endangers us with asteroids. Whether the big red spotted one is an overall benefit or menace I'm not sure. Of course if you extend no other planets to include no asteroids there would be no asteroids to menace us with.

ArgoNavis
2007-Nov-09, 03:27 AM
I have read that without Jupiter to clear out the debris of solar system creation, there would be a lot more minor rocks floating around. These would, over time, impact the Earth. No good for any life forms.

Also, the Moon is asserted to stabilse the obliquity of the ecliptic so that our seasons are stable and weather moderate. It also creates tides that may have a role in the development of advanced forms of life.

All of these are inimical to the development of life as we know it.

Ronald Brak
2007-Nov-09, 05:12 AM
Jupiter contains most of the non solar mass of the solar system. Now we can imagine a solar system the way it is but magically without Jupiter, but to say that without Jupiter there would be a lot of minor rocks floating around is problematic as it's difficult to say how the solar system would have formed without Jupiter. Above a certain amount of minor rocks and without Jupiters gravity affecting them these rocks would tend to form a planetary body. And if there were a lot of rocks and no Jupiter then without Jupiter to affect them there orbits would tend to be more stable.

And I certainly wouldn't say that Earth without a moon would be inimical to the development of life as we know it. It might be helpful to the development of life as we know it. For one thing it would help protect the earth against ice ages by helping to prevent large permanent ice caps from forming on land at the poles.

Noclevername
2007-Nov-09, 09:37 AM
The night sky would be a bit more boring. Astronomy as we know it might not have developed, or would have been delayed from developing for a very long time, as historically it sprang out of astrologies and religions which observed the movements of planets. If it did so at all, it would be quite different from what we know today. Science fiction would have also taken an entirely different path.

grant hutchison
2007-Nov-09, 01:01 PM
The Malkovitch cycles ...
Just in case anyone is trying to do a search for more information about these, that's Milankovitch, or Milanković.

Malkovich is the actor. :)

Grant Hutchison

Ronald Brak
2007-Nov-09, 01:24 PM
Dang, and I googled it to check I spelt it right and there it was, Malkovitch cycles. Probably the name of a motorcycle store.

Noclevername
2007-Nov-09, 01:27 PM
The Malkovitch Cycles is the sequel to Being John Malkovitch.

Ivan Viehoff
2007-Nov-09, 02:31 PM
If you google Malkovitch Cycles, the top reference is this page. The other two are the same malapropism.

Ronald Brak
2007-Nov-09, 03:02 PM
I see where I got it from now. The link I looked at goes to a page that suggests ice ages are caused by changes in John Malkovitch's moods.

laurele
2007-Nov-09, 04:44 PM
Just in case anyone is trying to do a search for more information about these, that's Milankovitch, or Milanković.

Malkovich is the actor. :)

Grant Hutchison

Are the Milankovitch cycles influenced at all by the other planets in the solar system?

grant hutchison
2007-Nov-09, 05:39 PM
Are the Milankovitch cycles influenced at all by the other planets in the solar system?Caused, to a large extent, by Jupiter and Saturn, with a contribution from Venus*. (Which I think is the point Ronald Brak was making about how the Milankovitch cycles would be boring without other planets to drive them.)
Perturbations from the gas giants and Venus drive the eccentricity cycle, the obliquity cycle and the steady movement of the perihelion. Precession of the Earth's rotation axis is driven largely by the Sun and Moon, and it interacts with the perihelion movement to produce a third cycle.

Grant Hutchison

*Edit: Do I mean Jupiter and Venus, with a contribution from Saturn? I think I probably do. :)

aurora
2007-Nov-09, 07:00 PM
Without Jupiter, the solar system would be totally different. Jupiter really cleaned out a lot of the system, and had an impact far beyond its current orbit.

Noclevername
2007-Nov-09, 08:59 PM
The OP doesn't specify what size bodies would be absent. Does it include dwarf planets/planetoids? Asteroids and comets? Or just the Big Seven?

John Mendenhall
2007-Nov-09, 10:10 PM
The OP doesn't specify what size bodies would be absent. Does it include dwarf planets/planetoids? Asteroids and comets? Or just the Big Seven?

I think I've just invented a new phrase of exasperation!

Or maybe a really bad pun on 'Oh, Susanna'.

neilzero
2007-Nov-09, 11:57 PM
While we are assuming, we might as well assume our solar system had most of the stuff it has now 4.5 billion years ago, but arraged, differently. A pair of mid sized black holes, remove all the planets except Earth and it's moon, when it passed though our solar system. Neil

Noclevername
2007-Nov-10, 12:13 AM
While we are assuming, we might as well assume our solar system had most of the stuff it has now 4.5 billion years ago, but arraged, differently. A pair of mid sized black holes, remove all the planets except Earth and it's moon, when it passed though our solar system. Neil

They'd have to move in some pretty funky patterns to remove every planet entirely, without affecting our orbit, and without scattering debris from their devoured meals across the system.

Neverfly
2007-Nov-10, 12:16 AM
While we are assuming, we might as well assume our solar system had most of the stuff it has now 4.5 billion years ago, but arraged, differently. A pair of mid sized black holes, remove all the planets except Earth and it's moon, when it passed though our solar system. Neil

http://picayune.uclick.com/comics/ch/1987/ch870113.gif

KaiYeves
2007-Nov-10, 12:38 AM
Just in case anyone is trying to do a search for more information about these, that's Milankovitch, or Milanković.
Malkovich is the actor.
And Cat Stevens is not the same as Kat Williams.

Ronald Brak
2007-Nov-10, 04:37 AM
And Cat Stevens is not the same as Kat Williams.

But if they got married they could have kittens.

laurele
2007-Nov-10, 06:04 AM
The OP doesn't specify what size bodies would be absent. Does it include dwarf planets/planetoids? Asteroids and comets? Or just the Big Seven?

The OP, who would be me, does not recognize the "dwarf planet" category as divergent from "planets," so the original intent of the post was the big eight or nine, as it now is including Eris. However, this leads to several related questions. What would be the affect on Earth if we had the asteroid belt but no planets? What if we had neither the asteroid belt nor the planets, or if we had random rocks floating around in various orbits but not located in any particular belt or region (is this last concept even possible?)?.

Noclevername
2007-Nov-10, 06:12 AM
The OP, who would be me, does not recognize the "dwarf planet" category as divergent from "planets," so the original intent of the post was the big eight or nine, as it now is including Eris. However, this leads to several related questions.

Plus Ceres.


What would be the affect on Earth if we had the asteroid belt but no planets?

We'd be bombarded more frequently than we are without Jupiter there to divert them.


What if we had neither the asteroid belt nor the planets,

Less major meteors. Dinosaurs might still be the dominant species in the food chain. Who knows where we would be, or if we would be.


or if we had random rocks floating around in various orbits but not located in any particular belt or region (is this last concept even possible?) Since there are many asteroids that aren't in the Main Belt region, it certainly is possible.

laurele
2007-Nov-10, 06:15 AM
"Plus Ceres."

I'm fine with that; make it the big ten. Thanks for addressing all these possibilties.

Ronald Brak
2007-Nov-10, 08:06 AM
We'd be bombarded more frequently than we are without Jupiter there to divert them.

Or less frequently than we are without Jupiter to divert them.

Noclevername
2007-Nov-10, 08:08 PM
Or less frequently than we are without Jupiter to divert them.

I'm not so sure; Comets gravitationally disturbed by Jupiter may be shot randomly at any direction, meaning they're more likely to be put on a vector that does not specifically cross our narrow orbit. I think.

aurora
2007-Nov-11, 06:19 PM
Or less frequently than we are without Jupiter to divert them.


That is only true in a solar system where the Jupiter sized planet cleared everything out early on.

Robert Tulip
2007-Nov-12, 08:01 PM
in the solar system (and would still have our Moon), would that affect its ability to produce life, its seasons and weather, etc. in any way or would there be absolutely no difference in conditions here if Earth were the only planet to orbit the Sun?
Ward & Brownlee in Rare Earth - Why Complex Life is Uncommon in the Universe, argue the existence of Jupiter, by vacuuming up such a lot of debris, is a key to providing the space and time for earth to have long stable ages such as those which ended with the Permian and Jurassic asteroid collisions. So, no Jupiter, no evolution of complexity. We would be pond scum, not anything more intelligent. Also, Ward & Brownlee say the moon stabilises the tilt of the earth enabling the seasons. I imagine the elemental composition of the earth is linked to its position in the primeval disk which coalesced to our solar system, so a system in which there were just sun earth and moon (three body problem!) would probably not be able to produce the same ratios of elements as we have.

Noclevername
2007-Nov-12, 08:08 PM
Ward & Brownlee in Rare Earth - Why Complex Life is Uncommon in the Universe, argue the existence of Jupiter, by vacuuming up such a lot of debris, is a key to providing the space and time for earth to have long stable ages such as those which ended with the Permian and Jurassic asteroid collisions. So, no Jupiter, no evolution of complexity. We would be pond scum, not anything more intelligent.

That's quite a bit of speculation! And a very self-assured title, too, considering how little data we actually have on the subject.

aurora
2007-Nov-12, 08:20 PM
It is a good read, though, I'd recommend it if you haven't read it.

Ronald Brak
2007-Nov-13, 02:58 AM
That is only true in a solar system where the Jupiter sized planet cleared everything out early on.

But without a Jupiter sized object their orbits would be a lot more stable.

Ronald Brak
2007-Nov-13, 03:06 AM
It is a good read, though, I'd recommend it if you haven't read it.

I have that book and I would say it's more of a headbanger than a good read. It suffers from a lack of logic and some things are just bizarre. For example on page 39 it says, "Fossil fuel and solar power could not possibly supply earth's human population, at its present rate of energy consumption, for more than a few thousand years." What the heck? Yeah I know fossil fuels are limited, but I think the sun's good for a while longer than that.