How many M-Class planets do you think there are?

[Asbo Zaprudder]

It's the continual copresence of oxygen with organic compounds such as methane and isoprene that is a better indicator. Chlorophyl or some analogue, of course, would be a dead giveaway, as would industrial pollutants or radioactive isotopes that do not occur naturally for advanced sentient lifeforms. However, too many of the latter two might mean said lifeforms are probably extinct by now.

 

[XCV330]

phosphorus is the problem too, a very big glaring problem.

https://www.researchgate.net/profil...-Role-of-Phosphorus-in-Chemical-Evolution.pdf


The universe was stingy with it. Sol system hit the jackpot. That's not to say there aren't other solar systems out there that also got enough of the elementl, had a small enough rocky world with a mainline star in just the right spot in their galaxy in just the right goldilocks orbit with just the right late period cometary bombardment to give it just the right amount of water for life to happen. But it kind of makes that number from 1001001 not entirely impractical.

 

[C Johnson]

One study estimates as many as six billion Earth-like planets in the Milky Way galaxy - one for every five Sun-like stars:

As many as six billion Earth-like planets in our galaxy, according to new estimates -- ScienceDaily

What does "Earth-like" mean? They're using that term for "the Goldilocks zone" (a planet around a seemingly friendly star, speculating the orbit may be a reasonable temperature); but that doesn't mean 75° and white sand and balmy ocean breezes blowing through palm trees.

I've watched virtually every Star Trek episode -- and they often go to planets where they don't need suits or helmets with air supply. And I'm just wondering, is there really more than one?

considering how many factors need to be juuuust right...I'd say they are probably not that common

I posted a link about the Moon. Jupiter is nice (it's a vacuum-cleaner protecting us from alot), there's a lot more "factors" than we think.

Maybe there's only two; and the second doesn't count...

 

[C Johnson]

With the "one in a million" I was really only speaking about our galaxy or galaxies like ours. I honestly don't know that much about astronomy beyond some basics and whatever I happen to read in articles and such.
I just felt that "one in a million" would be a reasonable figure. Thing is...we don't know. And we won't know until we have actually managed to explore more, and I have seen so many numbers over the years. I've read articles where it talked about 1 million inhabitable planets in the galaxy, or just 100.
This article from 2020 meanwhile says it could be as much as 300 million in our galaxy alone.
https://www.inverse.com/science/how-many-planets-host-life

And this all just talks about Earth like conditions, we still don't know what other ways complex life could evolve in alien environment. Heck, we don't even know whether Earth is the only planet with complex life in the Solar System (there's still things like Europa and Titan)

As for Star Trek, I mean, it works with the idea that billions of years ago a species manipulated evolution on countless worlds to result in something that resembles them and that's why there are so many planets with Earth like creatures and humanoids and why they can all interbreed.
For all we know that same species also terraformed countless planets to be more Earth-like, or some other ancient super civilization did it. Or the Q did it, for all we know.
That's why I don't really expect for Star Trek's version of the Milky Way to resemble ours all that much. I expect the Sol system to be there with its 8 planets and various dwarf planets and other objects, but even if Vulcan is located in 40 Eridani, I do not expect Star Trek's 40 Eridani to resemble "our"40 Eridani.

Well, about "evolution" -- we've never actually seen an increase in complexity, not in the lab, not in archeology, not anywhere. But if life "evolved" on more than one planet, kids between peoples would be (statistically) impossible. Spock was a Vulcan/Human hybrid; making me think, "...not a chance..."

I just think that so many things had to happen together for "life as we know it", probability for more than one would be unimaginably small. But then so many Star Trek plots would be borrrrring...

 

[C Johnson]

You can have sterile planets with a lot of oxygen as I recall.

Really. How can oxygen exist without life? It's not a stable material. I would think that entropy would push it towards oxides. Unless there were also no other reactive minerals; but Earth is rich in a variety of elements, what formation process could supply abundant oxygen but sparse things like metals?

 

[C Johnson]

1 confirmed but that one won't be around much longer since a species of stupid apes is doing their best to destroy it...

Who confirmed it? And what does your family album look like?

(...heh heh heh...)

 

[Orphalesion]

But if life "evolved" on more than one planet, kids between peoples would be (statistically) impossible. Spock was a Vulcan/Human hybrid; making me think, "...not a chance..."

Ignoring the first part of your post where you apparently try to discredit evolution...
Just responding to the part I quoted...
Ah-duuuuuuh!
Of course species evolving on different planets won't be able to produce offspring in real life, no matter how similar they might end up looking.
I was talking about Star Trek, where those precursors designed life and where humanoid species from different planets can produce offspring with varying degrees of ease and success.
That's just something that's endemic to the setting.

 

[C Johnson]

Ignoring the first part of your post where you apparently try to discredit evolution...

I wonder why you would ignore it? Truth doesn't need any of us; whatever is, is, with no regard to who objects.


Roddenberry of course was a "naturalist", so those themes are common through all of the series. Even though contradictions are blatant (one episode of TNG had life originating in a slime-pool on Earth, which Q showed to Picard, another had a message hidden in DNA from the other-planet-seeders...)

Just responding to the part I quoted...
Ah-duuuuuuh!
Of course species evolving on different planets won't be able to produce offspring in real life, no matter how similar they might end up looking.

Thank you! The probability of meiosis producing cross-planetary compatibility -- you're right, wouldn't happen. I mentioned above an allusion to some ancient race seeding the galaxy (TNG "The Chase"); in such a case, compatibility could be possible.

I was talking about Star Trek, where those precursors designed life and where humanoid species from different planets can produce offspring with varying degrees of ease and success.
That's just something that's endemic to the setting.

Precursor -- a person or thing that comes before another of the same kind; a forerunner:

Panspermia actually is external to discussions, because "we can't go there to see the origin place". In the show, "Stargate SG1", Humans from Earth traveled to many planets over thousands of years, therefore "compatibility".

Sadly, as someone said, we can't know if any "earthlike planets" (that is, planets living in the "Goldilocks Zone") have atmospheres. Dispersion denies us the ability to see planets around other stars (or even distant planets in our OWN system).

I had a homework problem, "Calculate the minimum diameter of a lens on a satellite camera at such-n-such altitude, to be able to resolve two inch license plate numbers". The answer was greater than three feet...

 

[publiusr]

Really. How can oxygen exist without life? It's not a stable material. I would think that entropy would push it towards oxides. Unless there were also no other reactive minerals; but Earth is rich in a variety of elements, what formation process could supply abundant oxygen but sparse things like metals?

Here you go:
https://thenextweb.com/news/yes-exoplanets-can-have-oxygen-without-alien-life-syndication
https://phys.org/news/2023-03-lab-oxygen-early-earth-atmosphere.html

In fact---some think that a planet explosion like Ceti-Alpha V might just have spawned the Moon
https://www.newscientist.com/article/mg21929242-000-tick-tick-boom-the-earth-spits-out-a-moon/

A paper on exo-worlds
https://arxiv.org/pdf/2104.11744.pdf

Remember how flat explosions became all the rage on film--Stargate---updated Death Star blasts...Praxis---and how that never really happens?

Um...
https://phys.org/news/2023-03-scientists-flattest-explosion-space.html

 

[XCV330]

I wonder why you would ignore it? Truth doesn't need any of us; whatever is, is, with no regard to who objects..

Because this is a science sub-topic. There's a Trek Tech forum to discuss Trek lore Founder Panspermia, and I suppose creationism could go into Science Fiction and Fantasy or Misc.

 

[Asbo Zaprudder]

How can oxygen exist without life? It is created in stellar cores and is the third most common element by mass in the universe after hydrogen and helium. Free molecular oxygen is very reactive so, yes, its presence in a planetary atmosphere suggests photosynthetic-like reactions are occurring, but non-biotic mechanisms have also been suggested.

Atmospheric oxygen can be created without plant life | Ars Technica

 

[C Johnson]

I heard something on tv yesterday, went surfing and found this article: https://www.discovermagazine.com/the-sciences/earth-may-be-a-1-in-700-quintillion-kind-of-place

I'm sorry it's a subscription site, when I viewed the page they said "one free article left without subscription". But it's an interesting article. Astrophysicist Erik Zackrisson from Uppsala University in Sweden considered the type of sun required, size of planet, orbit ("goldilocks zone"), and other criteria -- and computes the probability of everything coming together as for an earthlike planet to be one chance in 700 quantillion. That's a seven followed by twenty zeroes.

Zachrisson says that "Earth appears to have been dealt a fairly lucky hand". From his research he concludes that, statistically, Earth shouldn't exist.

And that's why there are those who try to stack the deck -- in a feeble attempt to overcome the staggering statistics (and those words are unimaginably understated), there must be a Multiverse, infinite parallel universes with infinite Earths. Think, television show "Sliders". Only then could infinite monkeys pound on infinite typewriters so that one eventually turns out Shakespeare. Our universe is not infinite, there are only so many monkeys (although I see things from politics to the postal service, I begin to doubt the simian limitation).

So I watch Star Trek, and they always go to planets where they run around blissfully space-suit-less happily huffing hospitable habitats -- Terran, Vulcan, Romulan, Klingon, Kardassian, Bajoran, Ferengi, Xindi, on and on. Even pleasure planets like Risa and "Shore Leave Planet". And I think, "riiiiiight." Nice try, but a SECOND viable biosphere would only be on a parallel Earth in a different universe.

...and I do not ascribe to "Multiverse" theory -- infinite conjectured universes are merely different branches of TIME, all may be real but only one valid. Which is why Marty had to go back to 1955 and retrieve Gray's Sports Almanac to unselect Biff's crime-synidicate universe ...errr, I mean, time-path.

Live long and perspire, Hawking and other "Multiverse" fantasy proponents.

{;-p

 

[C Johnson]

Of course, there is always another possibility -- if (from pure conjecture) some Captain Nemo in Earth's history figured out how to build an interstellar Nautilus, it would be entirely within reason to imagine crashing a few thousand comets onto a suitable "Goldilocks Candidate", either fortunately having sufficient magnetosphere to create radiation shields (or produce one by technology). Drop a few tons of plankton and some sea life, some sand and palm trees onto eligible islands, then yes grab the picnic basket and let's go! Not even any ants or mosquitoes to tarnish the respite!

{:-D

 

[publiusr]

Plate tectonics looks to have kicked off the Cambrian explosion.

 

[C Johnson]

Plate tectonics looks to have kicked off the Cambrian explosion.

How did plate tectonics do that?

Whenever I see a space show I wonder at the logistics of building a ship. There is no such thing as a perfect airlock, the air must be constantly replaced. That means significant energy to smelt oxides and produce free oxygen and a neutral part like nitrogen (although helium is funnier--and yes I know helium is noble). Most important is to scrub CO2 -- so producing hydroxides is a must (one episode of Stargate Universe dealt with that). Hydroponics might work on a ship-sized-scale, but eventually would fail, Thermodynamics #2 is only suspended when people talk of "parallel life on other planets".

A space suit is vastly more complicated for life support than a ship (air systems with lithium or sodium hydroxide, UV and infrared filters, kevlar for ballistic projectiles, on and on).

The idea of "colonizing other planets" is absurd, a habitat like in the movie "The Martian" would inflict disastrous radiation on occupants. Mars or lunar bases would absolutely have to be underground (ideally in caverns large enough to house spinning crews-quarters for normal gravity). Although Mars has plenty of CO2, there's really no getting around a need for a planet biosphere as a "fallback" or "base of operations". So planet scale terraforming is the only viable course.

I just thought it would be fun to ask ST fans what they thought of "M-class planets everywhere". The show wasn't credible -- like on episodes such as "Return to Tomorrow", where Spock said it was "an M-class planet", but moments later said "the atmosphere has been stripped away long ago" --- uhm, then it's not an M-class planet any more, Einstein!
}:-/

Some day maybe I'll have enough cash to buy a surplus space suit. One young enough so the incompatible materials will not have degenerated too much...

 

[Asbo Zaprudder]

M-class is a term from a TV show and varies according to plot demands. This is perhaps more suitable for discussion in Trek Tech.

 

[C.E. Evans]

I always figured that the percentage of M-class or Earth-like planets is very low, but given how big the Universe is, the actual number of such worlds is high. To me, Earth is an ultra-rare goldilocks planet in which many things had to line up and happen in a particular order to produce the world we have today. For most worlds this probably didn't happen, but even if only one world per galaxy is Earth-like, that's still a pretty big number, considering how many galaxies exist in the Universe, IMO.

 

[Asbo Zaprudder]

Current planet-hunting techniques aren't good at detecting extrasolar worlds with masses similar to Earth in the habitable zones around stars. We don't have a sound grasp of the probability distribution of types of planets or types of planetary systems. It might be that our solar system is an outlier, but neither our simulations nor our data sampling are currently good enough to make predictions with much confidence. I suspect there are power laws that must apply for such large numbers of stars and potential systems, with Earth-like planets being rare, but not having a vanishing small probability.

About 8% of stars in our Galaxy are similar to the Sun, so that's at least 8 billion potential candidates to consider even if one discounts the larger number of lower mass red dwarfs. (Counterintuitively, stars with only slightly higher mass than the Sun have much shorter life expectancy.*) One in five stars is thought likely to harbour planets, so the number reduces to 1.6 billion. Microlensing observations might give a better handle on numbers, given a few decades of observations. Direct gravitational lensing using the Sun's mass would be better, but we'd need to send thousands of suitable instruments well beyond the current distance of Voyager 1.

* Time spent on main sequence by a star is estimated as (M/Ms)^-2.5 times ten billion years, where M is the star's mass, Ms is the Sun's mass, so that's 10 billion years for the Sun. Very massive stars last less time and low mass stars last a lot longer than this equation predicts because of different internal convention regimes, but it should be a good estimate for K, G, and F type stars with 0.45 to 1.4 solar mass. According to Morgan-Keenan (M-K) spectral classification, the Sun is classed as G2V. The corresponding lifetime spent on the main sequence, before entering the red giant phase, would be from 73.6 billion years for 0.45 Ms to 4.3 billion years for 1.4 Ms. The lower end might well be to brief for complex life to evolve sufficiently so that it could either escape and survive the star's transition to a red giant or modify the star to extend its life.

 

[BK613]

You probably could factor in the cooler F stars and warmer K stars on the main sequence (say F8V to K2V) in order to up the numbers.

 

[Asbo Zaprudder]

You probably could factor in the cooler F stars and warmer K stars on the main sequence (say F8V to K2V) in order to up the numbers.

Probably so - my figure of 8% for Sun-like stars includes some type F and K stars as well as type G. The proportions of stars of different types are 0.0001% for type O, 0.1% for type B, 0.7% for type A, 2% for type F, 3.5% for type G, 8% for type K and 80% for type M. So, strictly type G would number 3.5 billion. Probably higher as we now think there might be as many as 400 billion stars in the Milky Way, rather than the usual estimate of 100 billion. We really don't have a good handle on the number. More instruments like Gaia would help reduce the size of the error bars.