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What’s the Most Earth-Like Planet In The Solar System?

11 Jul , 2013

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Life on Earth got you down? Thinking you’d like to pick up and move to another planet? I’ve got bad news for you. Without protection, there’s no place in the entire Solar System that wouldn’t kill you in few seconds.

You’re looking at scorching temperatures, poisonous atmospheres, crushing gravity, bone chilling cold, a complete lack of oxygen, killer radiation, and more.

The entire Solar System is hostile to life as we know it.

If we had to choose from a range of terrible options, what would be the most Earthlike place in the Solar System?

We would want a world that has a similar gravity, similar atmospheric pressure and composition, protection from radiation, and a comfortable temperature. Just like the Earth.

Let’s look at a few candidates:

The Moon looks good. It’s close and… well, it’s close. It’s an airless world, so you’d need a spacesuit. Low gravity is bad news for your bones, which will lose mass and become brittle. Temperatures range from freezing cold to scorching hot, and there’s no atmosphere or significant magnetic field to protect you from the radiation of space.

While we’re suggesting moons, how about Titan, Saturn’s largest Moon?

It’s only 15% of Earth’s gravity, and the temperatures dip down to minus -179 degrees C; cold enough that it rains liquid methane. Even though the atmosphere is unbreathable, the good news is that the pressure is only a little higher than Earth’s. Which means you wouldn’t need a pressurized spacesuit, just a really, really warm coat.

Turning on the Tap - Commissioned artwork - Colonist tapping into a sub-surface aquifer (©Mars Foundation)

Turning on the Tap – Commissioned artwork – Colonist tapping into a sub-surface aquifer (©Mars Foundation)

How about Mars, the target of so many colonization plans and sci fi adventures?

The gravity of Mars is only 38% the gravity of Earth; and we don’t know what effect a long stay in this gravity would have on the human body. The atmosphere is poisonous carbon dioxide, and the pressure is less than 1% of sea level on Earth. So, you’d better pack a spacesuit. The temperatures can rise as high as a comfortable 35 degrees C, but then plunge down to -143 degrees C at the poles. One big problem with Mars is a total lack of magnetosphere. Radiation from space would be a constant hazard for anyone on the surface of the planet.

Atmosphere of Venus. Credit: ESA

Atmosphere of Venus. Credit: ESA

Perhaps another planet? How about Venus?

On the surface, it’s right out of the running. The temperature is an oven-like 462 degrees C, with a surface pressure 92 times more than Earth. The atmosphere is almost entirely carbon dioxide, with clouds of sulphuric acid. On the plus side, it has gravity roughly similar to Earth, and a thick atmosphere that would protect you from radiation.

Unfortunately, you’d die faster on the surface of Venus than almost anywhere else in the Solar System.

But… there is a place on Venus that’s downright lovely.

Up in the clouds.

Cloud city of Bespin, from Stars Wars

Amazingly, if you rise up through the clouds of Venus to an altitude of 50-60 kilometers, the atmospheric pressure and temperature are the same as on Earth. The atmosphere would still be toxic carbon dioxide, but breathable air would be a “lifting gas” on Venus. You could float around the skies of Venus in a balloon made of breathable air. Stand out on the deck of your Venusian sky city in shorts and a T-shirt, soaking up the sunlight in regular Earth gravity.

Sounds idyllic, right?

So, opinions will vary. Some think Mars is the most Earthlike place in the Solar System, but in my opinion, the clouds of Venus are the place to go.

I’ll see you there.

Related Sources
Colonization of Venus
MarsOne Mission
Pros and Cons of Colonizing the Moon


Sort by:   newest | oldest | most voted
William928
Member
William928
July 11, 2013 10:56 PM

I’ll meet you in the Venusian clouds, Fraser!

hillsider62
Guest
hillsider62
July 12, 2013 1:37 AM

Just make sure your balloon would be acid-resistant.

Noah Peppin
Guest
Noah Peppin
July 11, 2013 8:40 PM

I always wonder why not go underground in these planets like the doomsday preppers

Coacervate
Guest
Coacervate
July 12, 2013 4:04 AM

I believe the temperature a few meters below earth stays a constant warm value as heat from the core works its way up and out. If this is true (and I’m not sure that it is) wouldn’t that mean the best place to be on the Moon Mars and Titan is a few meters underground? (and why are Earthian caves so chilly?)

IVAN3MAN_AT_LARGE
Member
IVAN3MAN_AT_LARGE
July 12, 2013 12:30 PM

[W]hy are Earthian caves so chilly?

See: Cave Meteorology.

Coacervate
Guest
Coacervate
July 12, 2013 10:50 PM

That is very interesting, thanks. The geothermal gradient on earth is smaller than I thought, 1 F per 70 feet. I wonder if the gradients of other worlds can be estimated from current models?

William928
Member
William928
July 12, 2013 11:16 PM

I wouldn’t think so, but if it’s possible, IVAN3MAN will provide the appropriate link(s). I’m too lazy to do the research. ;- )

IVAN3MAN_AT_LARGE
Member
IVAN3MAN_AT_LARGE
July 13, 2013 1:28 AM

According to this (PDF) paper, which asks the question, “Are Earth Caves Good Extraterrestrial Analogs?”, it states:

Which features of Earth caves can serve as reasonable representations of Mars and other planets and which features cannot be modeled on Earth? What are the relevant variables and the non-relevant variables between Earth caves and those caves found elsewhere? Clearly, the different gravitational constants of other planets are impossible to simulate in terrestrial caves. Indeed, we have not successfully simulated those fractional gravities experimentally anywhere yet. […].

Smokey
Member
Smokey
July 12, 2013 5:42 AM

A correction, if I may:

Carbon dioxide is no more “poisonous” or “toxic” than nitrogen. It is odorless, tasteless, and very much NON-toxic. It does not displace O2 in one’s system as carbon monoxide does, and it takes quite a bit of it mixed with water to make anything like a strong acid.

Granted, we aren’t plants, so breathing it INSTEAD of O2 isn’t wise. You would suffocate in a 100% CO2 atmosphere, just as you would in a 100% N2 atmosphere. But provided enough O2 is mixed in (and provided it IS CO2, not carbonic acid post-mixing with water vapor), the gas won’t “poison” you, or otherwise cause you any distress.

philw1776
Guest
philw1776
July 12, 2013 7:18 PM

I see your point but breathing just 5% CO2 will kill you while breathing lots of N2 is safe, assuming in both cases there’s 20% O2.

Smokey
Member
Smokey
July 12, 2013 8:11 PM

On one hand, using this rationale allows one to say that just about ANY gas could be considered “toxic” above a certain amount. But on the other hand, 5%+ CO2 will eventually lower the ph of your blood to dangerous levels, and you won’t be very comfortable while it’s happening since your breathing is regulated by CO2 pressure in the bloodstream (not O2 as most people think).
But since we ARE talking about atmospheres well over the 5% CO2 level, I think it’s fair to admit your point, Phil. Perhaps a compromise along the lines of “what is normally a non-toxic trace gas on Earth becomes poisonous at levels well below the higher concentrations found on Venus…” ^_^

Kawarthajon
Member
Kawarthajon
July 12, 2013 3:33 PM
I’m not sure that I’d like to live in Venus’ upper atmosphere, despite the pleasant temperatures. The winds whip around at 300km/hr and carry much more force than Earth’s winds because of the increased pressure (although, I acknowledge that you are talking about living in the upper atmosphere, where the pressure would be greatly reduced). These are regular winds and not storms or gusts. These kinds of winds on Earth are utterly destructive and usually associated with the worst storms. Imagine living in this kind of wind as part of your daily routine? I get seasick just thinking about it. I’m also not partial to sulfuric acid. My vote is for Mars. Yes, there’s bad radiation, but I’d… Read more »
Aqua4U
Member
July 14, 2013 4:03 PM
Generating a magnetic field on Mars…. I’ve often wondered if there might be a way we could somehow enhance and use existing magnetic anomalies on Mars? – http://www.princeton.edu/geosciences/people/simons/pdf/LPSC-2011.pdf – The MER Opportunity found one large NiFe meteor on it’s trek to Endeavour Crater. – http://www.universetoday.com/36498/opportunity-spies-unusual-rock-large-meteorite/ – Indicating there are probably many more laying on the surface waiting to be collected? How about… We collect those NiFe meteorites, melt them down and forge components for a very large geodesic dome structure? Locate the well grounded dome in an area of enhanced magnetic field strength – say above a buried giant metallic meteor remnant? Solar panels on the appropriate ‘great circles’ of the geodesic and collected tribo electric energy would… Read more »
Kawarthajon
Member
Kawarthajon
July 15, 2013 12:55 PM

Good thinking. I envision an autonomous robot that has the ability to melt down these meteorites and “print” them into a structure long before humans show up. Maybe also a robot to make the solar panels by melting down and “printing” silicon solar cells (I don’t know enough about the process to know if this is even feasible, but one can dream).

Now, if I could only find billions and billions of dollars to make this happen, we’d be there!

Lawrence B. Crowell
Member
Lawrence B. Crowell
July 12, 2013 7:17 PM
My advice is to skip planets and moons altogether. Outside of maybe some small research outposts I think planets are impossible places to colonize with large numbers of people. There is also considerable energy investment in getting on or off these bodies due to gravity. The interest in asteroids is probably the direction to go. Of course it will be a long time before this can happen, but potentially in a century we may be able to process all the materials of an asteroid. Some of it could be shipped back to Earth. Clearly there has to be some economic feedback for doing this. The other materials that are processed that have little commercial value on Earth could… Read more »
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