Help support TMP

"WHAT IF Earth And Mars' Orbits Were Much, MUCH Closer" Topic

36 Posts

All members in good standing are free to post here. Opinions expressed here are solely those of the posters, and have not been cleared with nor are they endorsed by The Miniatures Page.

For more information, see the TMP FAQ.

Back to the SF Discussion Message Board

Back to the Utter Drivel Message Board

850 hits since 26 Sep 2017
©1994-2018 Bill Armintrout
Comments or corrections?

Personal logo Cacique Caribe Supporting Member of TMP26 Sep 2017 8:47 a.m. PST

But not so close as to threaten a collision …

What effect, if any, would that have had on the development of human civilizations and belief systems?

PS. Not THIS close, of course, but close enough to see Mars more often and as a much larger object in our skies, visible day or night. :)


Vigilant26 Sep 2017 8:53 a.m. PST

Depends on how close. Could effect tides and atmosphere due to competing gravity which would have a pretty terminal effect for life on Earth.

Personal logo Cacique Caribe Supporting Member of TMP26 Sep 2017 8:56 a.m. PST

I mean close enough to become ever present but not close enough for serious physical effects on our planet.

I'm looking at how having a much closer "brother" would have affected our psyche, and the development of our religions, aspirations, etc, even our Sci-Fi literature?


Winston Smith Supporting Member of TMP26 Sep 2017 9:00 a.m. PST

What about the Moon? Where does that fit in?

Winston Smith Supporting Member of TMP26 Sep 2017 9:02 a.m. PST

Dudes with better math than me can come up with a stable tri-planet orbit around the Sun. Just stay away from Jupiter.
Want to throw Venus into the mix too?

Personal logo Cacique Caribe Supporting Member of TMP26 Sep 2017 9:12 a.m. PST

Lol. A planetary threesome? Why not.

I can imagine our social development becoming a lot "looser" there. And that dance of planetary bodies would have spawned some pretty crazy prayers too:

"Thanks be to the Mother, to the Father, to the 'Uncle' (Bob?), and to petite 'Aunt' Selene, who always seems to be particularly close to us."


dwight shrute26 Sep 2017 9:20 a.m. PST

Dejah Thoris could visit more often :-)

VCarter Supporting Member of TMP26 Sep 2017 9:31 a.m. PST

If Mars were closer then in may well be in the Goldilocks zone (with life) and we really could have a War of the Worlds.

Personal logo Extra Crispy Sponsoring Member of TMP26 Sep 2017 9:34 a.m. PST

The Moon God versus Mars God religious wars might have prevented us getting out of the stone age….

Ghostrunner26 Sep 2017 9:44 a.m. PST

Assume that Mars is in an independent solar orbit that brings it within observation range of Earth (see a disc with the naked eye) every 14 months or so.

Cultural impacts?

This would likely be viewed as far more relevant than the summer/winter solstices to pre-historic people. In fact, I could see a very strong belief system associated whether Mars brought winter or summer with it. (How many centuries would go by before it became apparent that Mars had nothing to do with the seasons?)

Human nature being the self-fulfilling prophecy that it is, if blood-red Mars was still associated with war, you can bet many regimes would consider it good luck to launch their wars when Mars was visible.

One could hope, though, that with very clear evidence of Mars not being visible from Earth for a good part of the year, that the Copernican/Galilean model of the solar system would come into being much sooner.

Personal logo Cacique Caribe Supporting Member of TMP26 Sep 2017 10:08 a.m. PST


Geesh. That is an insanely different path for mankind! Well, assuming the KT asteroid still hit us and not Mars, of course, so assuming we still had mankind and not lizardkind.


Personal logo Zeelow Supporting Member of TMP26 Sep 2017 10:39 a.m. PST

My good friend, Kasster the magician, said that "much much closer" would mean less transporter time from my place to Uxee Township, Zamazonia.

Personal logo Jlundberg Supporting Member of TMP26 Sep 2017 10:52 a.m. PST

Earth's orbit would have a lot more wobble in it, with potentially confusing seasons. Winter then it gets warmer due to tilt, then the warming is counteracted by moving further away. Fall could be similarly effected with the temperatures dropping off steeply or more gradually.
It would play heck with plant life and migration patterns

Personal logo StoneMtnMinis Supporting Member of TMP26 Sep 2017 10:53 a.m. PST

And, it would probably cause global warming!

Bronco Betty Inactive Member26 Sep 2017 11:35 a.m. PST

What a fascinating idea Dan.

If we were to be realistic(no fun, I know), Mars would probably be as barren as the Moon. This is because Mars has a much weaker gravity which causes its atmosphere to be stripped away by the Solar winds. Putting it in a closer orbit would only speed the destruction of its thin atmosphere,

If we were give close Mars a stronger gravity core to retain an atmosphere, then as Jlundberg said, there would be seasonal and orbital impacts on the Earth.

Sometimes reality is just no fun!

Ottoathome26 Sep 2017 11:36 a.m. PST

Dear Dan

Leaving the science aside with regard to atmosphere, tides, techtonics orbits, I am keying my remarks on your requirement that Mars would be a visible disk. Mars is pretty small and that would mean it would have to be much closer to get a disk out of it, and depending how much or big a disc would bring it to a distance not much farther than the moon. This would impose the categories we would like to leave aside as listed above. But assume that it was just on the side where it could be seen as a disk, that would make it the third most important object in the sky, the first being the sun and second being the moon.

You have specified what would be the effect on human BELIEF systems so I will address that. I suppose that importance would be on size. That is according to the SIZE of the martian disk compared that of the sun and moon and the relative brilliance, it would have been an effet that would be rather marginal given size. Maybe the personification of a particular God or the idea of a nemesis God, but I think it would have fitted in rather easy.

But no matter how close it was it would not convince the "Flat-Earthers" that they were wrong.

Consider even at the proximity of your illustration you would still not be able to see any effects of life on the other planet or detect anything till radio waves and signals came along on either sphere, it is hard to prognosticate what the other sphere may be.

Winston Smith Supporting Member of TMP26 Sep 2017 11:36 a.m. PST

I'm still not willing to make the Moon go away. grin
Bring on Mars. Let's compare diameters.
Mars is roughly half of Earth. The Moon is roughly a quarter.
Astronomers have found many triple stars in stable orbits with each other.
Then put that trio in orbit around the Sun.
Tidal forces stabilize orbits, sometimes adding heat energy to all bodies.
So, let's assume that all this stabilizes a half billion years before "life" emerges. Maybe simultaneously on Mars and Earth, with random meteor strikes spewing early amino acids into Space.
Or our system is a 14th Grade Science Project for some Aliens somewhere.

Life would have evolved to deal with any orbital peculiarities. Orbits are stable, life copes. Earth abides. Mars abides.
We have the Sun, obviously the most powerful. We have red Mars ( will it still be red, if life forms?), white Moon. I guess Mars comes on after the Moon forms from some collision or other, but a lot of scenarios are viable.

My point is that life is unlikely to evolve anywhere until the billiards stabilize into stable orbits. And life would evolve to cope to this unique circumstance. Doesn't it always? Look at Earth, and the strange places life thrives. Thermal springs anyone?

And humanity would have evolved with those undeniable disks in the sky. As would have civilization.

Winter is coming. grin

Winston Smith Supporting Member of TMP26 Sep 2017 11:43 a.m. PST

Neil Armstrong might have had to go in shooting.

Lion in the Stars26 Sep 2017 12:16 p.m. PST

@Bronco Betty: The big reason Mars has been stripped of most of it's atmosphere is because there's no major magnetic field to keep the solar winds away.

And there's no magnetic field because the core has solidified.

Assume a Mars with a still-hot core, you could have a Mars with life. Mars is still technically within the Goldilocks Zone, I think Mars defines the outer edge.

Winston Smith Supporting Member of TMP26 Sep 2017 12:21 p.m. PST

Maybe the heat energy absorbed by Mars to tidally stabilize its orbit would have started its innards flowing to create a magnetic field.

Consider this speculation by a guy who last took a physics course in the 1970s and browsed Scientific American since. grin

Rogues126 Sep 2017 12:31 p.m. PST

Werewolves would come out every Full Mars?

Ghostrunner26 Sep 2017 12:35 p.m. PST



Personal logo piper909 Supporting Member of TMP Inactive Member26 Sep 2017 1:52 p.m. PST

We could go there and conquer it!

Um, or vice-versa.

DyeHard26 Sep 2017 2:14 p.m. PST

Not to ride the physics too much, but for Mars to appear as large as the Moon from Earth, it would have to be just 786100 km away (or just a little over twice as far as the Moon).
If Earth's orbit is 1 AU than Mars would be 1.005 AU. And Mar's year would be about 367.8 days long. So, it would come close about every 143 years. You could have fun with the moon eclipsing Mars and even the Earth or Moon casting shadows on Mars. It would be a bit tedious to calculate how far Mars could be and still be visible during day time, but a Mars that looks 5% the Moon's diameter would be out some 9 Million km (at 1.061AU from Sun) and would come around every ten years or so.

Bronco Betty Inactive Member26 Sep 2017 2:27 p.m. PST

@ Lion in the Stars

Thank you for correcting my mis-statement(and not being creepy doing it). :)


mwindsorfw Supporting Member of TMP26 Sep 2017 3:07 p.m. PST

We could wave as Mars goes by.

Personal logo Cacique Caribe Supporting Member of TMP26 Sep 2017 3:34 p.m. PST

That would have been so cool. Waving to our cousins just as they wave back.


taskforce5826 Sep 2017 5:06 p.m. PST

DyeHard wrote:

Not to ride the physics too much, but for Mars to appear as large as the Moon from Earth, it would have to be just 786100 km away (or just a little over twice as far as the Moon).
If Earth's orbit is 1 AU than Mars would be 1.005 AU. And Mar's year would be about 367.8 days long. So, it would come close about every 143 years.

A Martian orbit of just 1.005 AU would not be a stable one. With my limited understanding of astro-dynamics (from playing too much Kerbal Space Program and spending a lot of time googling the subject), Mars would either :

i) be captured in Earth's L4 or L5 Lagrange Point and become a Trojan Planet. In laymen's term this means it would permanently occupy a position 60 degrees ahead or behind of Earth's orbit. This means from Earth's POV it would always rise/set roughly 4 hours before or after sun rise/set.

ii) Mars captured by Earth and becomes Earth's satellite. This is a much more serious scenario. Assuming the Earth-Mars distance (measured from their center) is 786,100km as DyeHard suggested:
--- Earth and Mars both orbits their barycenter, which is a point directly between the two bodies, about 76,320km from the center of the Earth (about 70,000km above Earth's surface).
--- Mars would exert slightly more than twice (about 2.1 times) the gravitational pull on Earth as the Moon does on Earth. I assume this would have a significant effect on Earth.
--- I won't even touch on how this would affect the Moon's orbit. That kind of math goes way above my head. For reference, Earth's mass is about 9.3 times that of Mars, and Mars is about 8.7 times that of the Moon.

Personal logo Landorl Supporting Member of TMP26 Sep 2017 5:12 p.m. PST

A little closer and Mars would really be suitable for life.

Winston Smith Supporting Member of TMP26 Sep 2017 6:15 p.m. PST

Thank you taskforce58.
You did it better than I could.

Winston Smith Supporting Member of TMP26 Sep 2017 8:08 p.m. PST

And if Mars is captured by Earth, to stabilize at that distance, the tidal forces would certainly warm up Mars's core. And probably Earth's a lot more. Hmmm… maybe no people on Earth, but instead on Mars! grin

Personal logo Cacique Caribe Supporting Member of TMP27 Sep 2017 2:12 a.m. PST

So maybe an inhabited Mars, but with a "post apocalyptic" Earth in a nearby orbit and often visible?

Move over Atlantis. The morality tales they would craft from Earth's demise would spawn many interesting belief systems on Mars.


Mobius27 Sep 2017 5:57 a.m. PST

The planets are fairly widely separated. This probably isn't an accident and is needed to keep their orbits stable. If they were too close they probably would affect one another and one or the other might have been kicked out of the solar system or thrown into the sun.

The distance to the orbit of Venus is about half that to Mars. So Mars could probably have a stable orbit at an distance 24 million miles closer. Since it doesn't have a strong magnetic field the suns radiation would of dried it up even faster.

DyeHard28 Sep 2017 7:56 a.m. PST

The Trappist-1 system shows that planets can very very close indeed

Just look, 1 AU is spacing from Sun to Earth:


Winston Smith Supporting Member of TMP28 Sep 2017 8:34 a.m. PST

There you go CC.
How do you like 6 visible disks in the sky?
Quite lively spectacle too.

I bet mathematics evolved quite rapidly there, particularly if the inhabitants had 5 fingers and a thumb. Base 12 is really more practical.

Personal logo etotheipi Sponsoring Member of TMP28 Sep 2017 9:23 a.m. PST

One could hope, though, that with very clear evidence of Mars not being visible from Earth for a good part of the year, that the Copernican/Galilean model of the solar system would come into being much sooner.

Cultural nothing established the relative places of geocentric and heliocentric models of the solar system. The fact that the Copernican/Galilean model is wrong was the major factor.

Sorry - only verified members can post on the forums.