Could Some Alien Worlds Be More Habitable Than Earth?

There is a great story on Nat Geo talking about habitable exoplanets. More specifically, some of the worlds we are detecting which may be -more- habitable than the Earth.

(thanks to AliceBleachWhite for the tip)

People often think of the Earth as the epitome of habitability. For good reason, we're here and everywhere we look there is life. However there are other planets out there which may be even more habitable than the Earth.

Here are a couple "Did you know?"s before an excerpt of the article on Nat Geo:

1. Did you know that Earth is a fairly dry planet? We think of it as a very wet world because water covers a good portion of surface area yet if you took all of the water in the world and placed it in a ball this is the proportion of the Earth by volume that is water:



We know of worlds which have even more water by volume than the Earth. Perhaps they are even more habitable? All life as we know it needs water. Specifically liquid water. A planet with more of it than Earth may have an even higher abundance of life.

2. Did you know that Earth doesn't exist in the middle of our solar system's habitable or "Goldilocks" zone? People tend to think the Earth sits smack in the middle of our Solar System's habitable zone but in reality it is near the inner edge of it as shown in this graphic which compares our system to the Tau Ceti system's habitable zone. (shown in green).



We know of planets which sit smack in the middle of this zone and there are other factors which make planets habitable as well, perhaps even more habitable than our Earth.....

3. Did you know that there isn't just one definition of a habitable or "goldilocks" zone? The graphic below illustrates why this is:




So with that in mind...

Here's an excerpt of the article:

Planet hunters have always been keen to find Earth's twin, but an astrobiology team now suggests that "superhabitable" planets may be even better places to look for alien life.

Since 1995, astronomers have detected more than 1,000 worlds orbiting nearby stars, sparking a race to find the one that most resembles Earth, blessed with oceans and an oxygen-rich atmosphere. That's because Earth is the only place in the universe where we know that life has evolved. (See: "More Than 1,000 Potential New Planets Found.")

In the journal Astrobiology, however, researchers René Heller of Canada's McMaster University and John Armstrong of Weber State University in Ogden, Utah, calls that idea too Earth-focused. "From a potpourri of habitable worlds that may exist, Earth might well turn out as one that is marginally habitable, even bizarre from a biocentric standpoint," they write.

Instead, they suggest that astronomers should focus their planet hunting on worlds that might harbor conditions even more amenable to life. The authors dub these hypothetical worlds "superhabitable." (See "Think Outside the Box to Find Extraterrestrial Life.")

Their report adds to a chorus of voices in the planet-hunting community that have called for rethinking the idea of "habitable zones" where worlds that follow orbits friendly to oceans and life would exclusively exist.

Water Worlds

What characteristics might make a world superhabitable? Like all potentially habitable worlds, they should have water, agree Heller and Armstrong. But they list more than a dozen additional geological and atmospheric factors that could influence habitability.

For instance, older planets would presumably have had more opportunities for life to evolve. Larger worlds, ones up to three times as massive as Earth, might be more likely to have an atmosphere due to more volcanic activity, which releases gases.

Earth itself is thought to be located on the fringes of the habitable zone, they note, so maybe planets that are located nearer to the center of the habitable zone are more congenial to life.

Scientific Skepticism

Other scientists disagree about the usefulness of the concept of superhabitability. "A planet is either habitable or it's not," says atmospheric scientist Jim Kasting, who first introduced the concept of the circumstellar habitable zone, which defines a planet as habitable if it orbits its star at a distance where it's not too hot and not too cold for liquid water to form on the planet's surface.

Similarly, astrophysicist Steven Desch said that "calling a planet superhabitable is comparable to calling someone only a little bit pregnant ... Having more of what is needed for life, in my mind, doesn't make it more likely to have life."

But Ravi Kopparapu, a physicist at Penn State University, agrees with the authors that the "binary" habitable zone concept (either friendly to life or not) is too restrictive. Plenty of worlds within the habitable zone are unlikely to support life, while others—such as the icy moons of Saturn and Jupiter, which may have vast underground oceans—could potentially support life but fall outside the habitable zone. As scientists continue to discover a menagerie of exoplanets, considering more variables could help to prioritize which planets to target for follow-up.

Continue reading at NatGeo...


This is interesting because it shows that with regards to habitability our ideas may be too influenced our Earth-bias.

Might we miss detecting life on other words far sooner than current plans call for by skipping worlds unlike the Earth but perhaps just as habitable if not more habitable?

Here is a cautionary tale that is a true story....

In 1995 when the first exoplanet was announced by a Swiss team of astronomers orbiting the star 51 Pegasi and American team made up of Geoffrey Marcy and Paul Butler was stunned.

The technique the Swiss team used was identical to theirs and the American team had taken data for some time but had not examined it to see if any planet existed as the Swiss team did.

Why didn't they? Because they made an assumption based on our solar system that they wouldn't find anything for 10 years because the type of planet they were looking for, a Jupiter sized planet was assumed to only orbit far out from its star. So they thought, "why bother looking, most planetary formation models have big gas planets forming and orbiting far out, it will be years before we see anything in our data."

The Swiss team made no such assumption and made the first discovery of an exoplanet around a Sun-like star. It just so happened that massive planets like Jupiter do sometimes orbit very close to their stars.

The discovery of that planet could have been made had Marcy and Butler looked at their data, they had even collected data on the same planet as the Swiss team.

The American team had to just be content with verifying the Swiss team's discovery.

Now the American team went on to make plenty of discoveries of their own and for quite some time has been the top planet hunters in terms of the technique that was used to find 51 Pegasi b, 47 Ursa Majoris b, Tau Bootis b, etc.

But they missed out on making that first discovery due to an assumption about what is out there which was based on what was our only known planetary system (our solar system) at the time (1995).

Lesson: If physics and chemistry do not prevent it, do not write it off. And always check your data even if you don't think anything is in it

The Goldilocks zone is between Venus and Mars, as a reference only being directly in the middle wouldn't make it more habitable.
Earth isn't a dry planet, liquid water covers 70% of the surface, At any moment, the atmosphere contains an astounding 37.5 million billion gallons of water, in the invisible vapor phase. This is enough water to cover the entire surface of the Earth (land and ocean) with one inch.
of rain.

My opinion is no other planet is more habitable than ours for our type of species, we evolved with the Earth. Let's hope we don't ruin her !

Finally and hopefully stubborn 'scientific community' is on the way to learn what thinking out of the box really means.
Thinking we know it all isn't going to get us nowhere.
Thanks for this Jade, quite the refreshment.

reply to post by muSSang


She's saying there are planets that have less terra and more aqua, with majorly different proportions than our planet. So maybe, 10% terrain, 90% surface water, and maybe oceans that are two to three times as deep.

I couldn't imagine being that isolated though. I'd want to advance my species to move out quick

muSSang
The Goldilocks zone is between Venus and Mars, as a reference only being directly in the middle wouldn't make it more habitable.

It would in some respects. A lower solar flux of UV as well as less desertification might make it more habitable. It would also make it slightly less prone to greenhouse warming.

Earth isn't a dry planet, liquid water covers 70% of the surface

Actually it is and the graphic I posted demonstrates this. All of that water in the ball spreads out thinly atop the crust of the Earth. So while 70% of the surface area is water, the water layer is thin.

You're confusing surface area with volume. Compared to some other planets which we know have a higher density of water, our planet's oceans are likely shallow.

At any moment, the atmosphere contains an astounding 37.5 million billion gallons of water, in the invisible vapor phase. This is enough water to cover the entire surface of the Earth (land and ocean) with one inch.
of rain.

One inch is not very deep.

What if I told you we know of several planets which instead of one inch would be one foot, or even one mile?

My opinion is no other planet is more habitable than ours for our type of species, we evolved with the Earth.

Why the species chauvinism?

We're talking about detecting LIFE in all its glorious forms. Not just human life.

Other species would evolve perhaps even sooner in a slightly friendlier environment to life...

Let's hope we don't ruin her !

Agreed. We only have one blue marble. Let's try not to lose the ones in on heads!

zilebeliveunknown
Finally and hopefully stubborn 'scientific community' is on the way to learn what thinking out of the box really means.
Thinking we know it all isn't going to get us nowhere.
Thanks for this Jade, quite the refreshment.

That's why I posted it.

There's a view on ATS (and i dont know where it comes from) that science is stuck on stupid and doesn't think outside the box. But you can read plenty of papers on ArXiv which run the gamut of slightly innovative to wildly speculative out of the box thinking. Occasionally one like this gets reported in the mass media and is worthy of posting.

Lynk3
reply to post by muSSang

 

He's saying there are planets that have less terra and more aqua, with majorly different proportions than our planet. So maybe, 10% terrain, 90% surface water, and maybe oceans that are two to three times as deep.

It's she (i'm a girl). And you are absolutely right.

It would make for a fisherman's paradise though wouldn't it?

reply to post by JadeStar


S&F Jade.

I really think your super intelligent and after debating with you a few times i know for sure you are. Cool thread there isn't enough threads on ATS like this in the last 2 years since 2012.

I would love hear your ideas on theoretical and "speudo-scientific" ways of thinking if you could open up to it more. You could really bring a lot to the table. Thinking creatively can really help you get to know yourself and hey maybe youll discover something.

Its a great point there could be planets with far more stable and weather systems. In fact its a garentee that somewhere a world exists like that.

if the planet has molten boron seas and a landmass of solid cobalt, only one McDonalds and no "real housewives of..." where can i apply for citizenship !

crazyewok
Its a great point there could be planets with far more stable and weather systems. In fact its a garentee that somewhere a world exists like that.

yes. there is a place like this. it's called Guam. no kidding. loved living there. great beaches. excellent climate. fun and friendly people. totally awesome fiesta's and in the Summer months? on some of the golf courses you can hit a drive about 7,000 yards! the coral and mud dry out on the fairways in some spots so bad it's like concrete plus, if your ball goes down one of the huge cracks that open up in the ground because of lack of watering, you can take a mulligan! and it's out in the middle of NOWHERE! ! i totally recommend the planet Guam !

reply to post by JadeStar


S+F for posting!
I thought you'd like it.
I wouldn't have been as thorough, and you've done a wonderful piece.

reply to post by JadeStar

We need healthier environment within scientific community, I mean who knows how many geniuses are there being afraid to publish their papers in scare of ridicule, that's the problem I'm seeing.

Oh, I hope soon, I'd like to see from you some papers published on astrobiology and your ideas on how would you be looking for life elsewhere, I'm sure you have a couple of aces on your sleeves

Odds are that there's probably millions of better candidates than our home planet. Just thinking of that potential in and of itself is pretty mind boggling.

Let's just hope we can actually find one and figure out a way of getting there before we kill this one off... Unfortunately, budgetary funding dictates that the odds of achieving such a feat will most likely be next to nada.

After the way we crapped up this planet.
i would say yes.
How much is a ticket?

Oh i wanted to answer the question in your thread title.

I hope so because if not were screwed and i hope we find a way to get to them because the universe is going to balance us out and i hate to see how it does it.

reply to post by JadeStar


After reading through the Hill-Fish star map thread where you go into incredible detail (WHERE IS YOUR THREAD AND VIDEO...TUT TUT!!!)...including an Astronomy 101 class regarding stars and habitable zones...I was educated to the fact that we sit on the inner zone of the HZ.

Does this mean that eventually mars will be more habitable than Earth as our Sun expands further expanding the HZ outwards?

reply to post by JadeStar


Only a girl? You give me the impression you are a woman!!!

Just a couple of points.

1.) If you had a planet like Eden, "perfectly" habitable in every way, would you ever put on clothes?

2.) If you believe "we" have screwed up this planet and would gladly buy a ticket elsewhere to a place much more pristine and unsullied, do you truly believe that "you" (including your descendants) would not screw up that place, too?

The issue with 1) is that a perfectly habitable planet might not be the best one to create a civilization on. By "civilization," I mean one that is capable of leaving the planet for another one, which is a true indication of survivability. Earth is about half-way through its lifecycle. Sooner or later the Sun is going nova and we will be crispy critters. If our species is to survive, it must leave. A planet which affords a relatively easy life does not spurn you on to other discoveries. Adversity causes invention.

The issue with 2) is that no matter how enlightened we all think we are, there is no indication that our enlightened ways would survive beyond a generation or two. Human nature is what it is, with no built-in mechanism of self-restraint. We've seen how attitudes can change in a few decades. There is no reason to think future generations of us on a different planet might come to see it as a source of resources to be picked over rather than a Gaia-like living being to be nurtured.

"Habitability" is not all about having a bowl of porridge that is just the right temperature. Earth is the most habitable planet for humans by definition. We were born, evolved here, and have come to dominate here. We are extremely successful as a species. (If you believe we came from some other planet, feel free to continue with your delusions. The fossil and DNA evidence suggest otherwise.)

Certainly we need to seek out other habitable planets as soon as possible. Our future depends upon it, but let us not suffer the illusion that Earth is somehow not good enough.

I'm just a simple bunny...but it seems to me that nowhere but Earth is better suited to the life on Earth. Nothing particularly special about Earth, perhaps, and I think we'll actually come to see that as very true once we move into deep space and across the distances to other systems.

It's just that life has evolved specifically to this climate, gravity, temperature range and eco-system for life we share it with. Kinda...tailor made Earthlings by natural process, aren't we?