Talk:Planetary habitability

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Merge content from Goldilocks planet and Goldilocks Principle[edit]

(Since the proposer failed to create a discussion topic, I have done so).

I oppose this proposal. I would support a proposal to merge them in Habitable zone. --John Maynard Friedman (talk) 12:31, 17 December 2009 (UTC)

I wasn't aware of this discussion, but yes, I think your proposal is a good one. Serendipodous 13:06, 17 December 2009 (UTC)

Oppose merging Goldilocks Principle, as this is in fact more general than just in astronomy. It can be used in relation to any rise of complexity (which includes various phenomena of human history). --JorisvS (talk) 18:35, 15 January 2010 (UTC)

I did in fact create a discussion but it was archived, it currently resides here. Icalanise (talk) 19:34, 2 April 2010 (UTC)

2010 Paper[edit]

I came across this research paper which I blieve can be mined for information for this Wikipedia article: [1]. --BatteryIncluded (talk) 03:18, 26 July 2010 (UTC)

quidquid latine dicitur alte videtur[edit]

Mars, with its thin atmosphere ...
Mars, with is rarefied atmosphere ...

What value is added by the fancier word, or by the link? The article Rarefaction sheds no light on why the Martian atmosphere is thin. —Tamfang (talk) 21:24, 4 October 2010 (UTC)

"Thin" is ambiguous (a similar objection applies to "thick"). It can be interpreted as both "low in density" and "not extended" (hugging the planet's surface). Since atmospheric density and scale height are independent parameters, and only the "low in density" definition is applicable to Mars, it pays to be more specific. The link defines the term for those not familiar with it. WolfmanSF (talk) 20:06, 10 October 2010 (UTC)
Seems to me the relevant point of that sentence (that it makes Mars colder than Earth would be at the same distance) concerns not the density but the optical depth, the cumulative opacity to infrared; so thin is applicable in either sense. How about scant? —Tamfang (talk) 19:56, 14 October 2010 (UTC)

My main objection to rarefied is that it implies that the atmosphere has been made less dense, and the article reinforces that implication. That may be true (i.e. maybe it was heavier in the past) but it's a distraction. —Tamfang (talk) 21:12, 10 October 2010 (UTC)

Actually, it doesn't imply that, although if it did it would be correct. It is simply the best term I could come up with for "very low in density". It's not arcane. If you can come up with a better term, use it. Alternatives might be "tenuous" or "insubstantial", but they don't mean "very low in density" as explicitly. WolfmanSF (talk) 10:05, 11 October 2010 (UTC)
Does too. :( —Tamfang (talk) 21:01, 11 October 2010 (UTC)
Nonsense. Here is the first definition from the first dictionary I checked: "(of air, especially that at high altitudes) of lower pressure than usual; thin". source WolfmanSF (talk) 02:44, 12 October 2010 (UTC)
One can't rely on the reader to consider only the first meaning in a dictionary, no matter how good the dictionary. It's the passive participle of a transitive verb, of a family of verbs (–fy) that do not suggest stasis.
But I've better things to do than press that point all by my lonesome. —Tamfang (talk) 19:20, 14 October 2010 (UTC)

Geometry 101???[edit]

Secondly, smaller planets have smaller diameters and thus higher surface-to-volume ratios than their larger cousins

Er, don't all bodies of the same shape have the same surface to volume ratio regardless of size? This is Wiki's finest? —Preceding unsigned comment added by (talk) 05:39, 29 October 2010 (UTC)

Nope. Consider two cubes, whose edge lengths are 1 unit and 2 units. The first has surface 6 square units and volume 1 cubic unit, for a surface-to-volume ratio of 6 inverse units. The second has surface 24 square units and volume 8 cubic units, for a surface-to-volume ratio of 3 inverse units. —Tamfang (talk) 05:17, 5 November 2010 (UTC)
s/v ratios are relative, not absolute, so it is important that any comparisons are made using the same units. s/v ratio of a 1cm sphere is 6. s/v ratio of a 1km sphere is also 6, but if calculated in cm it becomes 6E-10. Plantsurfer (talk) 12:07, 27 May 2013 (UTC)

Narrow-minded 'Habitable' concept[edit]

This article is seriously flawed, due to narrow-mindedness. I'm astonished it was approved as a Featured Article. Life and 'life as we know it' (LAWKI) are FAR from the same thing. This article states numerous times that life requires all sorts of very particular things, statements for which there is usually little to no support, except when sources are misconstrued (or misread or read out of context).

Problems like those raised here are numerous. Exemplary Case: When this discussion took place, I think it was the case that all LAWKI required phosphorus. But, we now (as of a couple months ago, thanks to the open-minded Felisa Wolfe-Simon) have strong evidence that life does NOT require phosphorus.

Certainly it was true that "LAWKI requires phosphorus". But it was neither true nor reasonable to have said "life requires phosphorus". And yet we are still doing that - saying life requires a planet in a HZ, with a moon, enough of various elements, like metals...

I propose slight tweaking throughout the article, where warranted, to dial back the overarching claims or re-word things to apply to LAWKI, not life.

Here are some problematic sentences: The first one:

Planetary habitability is the measure of a planet's or a natural satellite's potential to sustain life.

But the current article actually is mainly about a planet's potential to sustain LAWKI. So, which way do we tweak the article? To be about sustaining any form of life, or LAWKI. I think the latter makes more sense. Agreed? (Maybe we should describe it as a theory that habitable planets are those that would support the evolution of life as we know it, and that it is based on the questionable assumption that extraterrestrial life is most likely to have evolved much like life as we know it on earth.)

Another one:

0.3 Earth masses has been offered as a rough dividing line for habitable planets.

Sure, this is true if "habitable planets" refers to habitability by LAWKI, but not if it refers to all possible life. "It's life, Jim, but not as we know it."

  • -Famous (mis-)quote from a Star Trek episode.

--Elvey (talk) 09:14, 25 January 2011 (UTC)

Alternative lifeforms are discussed in the article hypothetical types of biochemistry, to which this article has a link and a subsection. The issue is also dealt with in the opening paragraphs. Given that such lifeforms are pure speculation at this point, it is difficult to see how we could reasonably expand the article to include them. Just off the top of my head I can conceive of a lifeform made of dark matter that fed of zero-point energy, or a lifeform made of neutronium that lived beneath the surface of a neutron star, or a lifeform that floated like a bubble through an interstellar cloud, feeding off stardust. Should this article include them? Serendipodous 09:39, 25 January 2011 (UTC)

Top 5 list[edit]

I think it would be really great to have a section or sub section listing the current top 5 or so candidates for habitability. I know this could be very debatable but it would be great for readers to be informed about the exoplanets that at the moment seem the most likely to be able to have the right conditions.Douglas.hawkes (talk) 15:25, 17 September 2011 (UTC)


Dov Henis (comments from 22nd century)

Dov Henis (talk) 06:15, 1 October 2011 (UTC)

I am unclear as to what you want. Serendipodous 07:17, 1 October 2011 (UTC)

Add mention of Planetary boundaries?[edit]

Add mention of Planetary boundaries. (talk) 00:37, 17 June 2012 (UTC)

Since it has damn all to do with predictions of the habitability of extrasolar planets, it's nothing but propaganda for green zealots on this page. (That's quite aside its extremely dubious credentials even for earth...) TREKphiler any time you're ready, Uhura 03:12, 17 June 2012 (UTC)

Astonished - Propose rename to "Requirements for Complex Life on Earth" ...[edit]

I am astonished that this was a feature article. It is riddled with anthropic reasoning and narrow mindedness that makes it practically a recital of "Rare Earth" and "The Privileged Planet". I'm starting to wonder, not whether it should be a feature article, but whether its worth the article existing at all ... at least that is until life is found elsewhere. The article pretends to be about life, and then twists the concept toward worlds friendly to life as we know it. Life is life, it really shouldn't matter whether it is a giraffe or a microbe. Simple concept. --EvenGreenerFish (talk) 03:06, 27 May 2013 (UTC)

Such a drastic response would IMO destroy valuable information. Yes, the page is astoundingly anthropocentric (or geocentric, or both). This is the usual bias among Terran scientists, regrettably, who aren't trained (nor, usually, expected) to think about anything genuinely extraterrestrial. (Unlike SF writers...or fans. :) ) Until they are, I see no prospect of change. Failing that, I suggest we should keep what we can & make it as clear as possible there's a strong geocentric bias. (This may require creation of a new template. ;p ) TREKphiler any time you're ready, Uhura 03:17, 27 May 2013 (UTC)

Red Dwarf habitability needs some work[edit]

The section is written mostly based on the assumption that any potentially habitable planet orbiting a red dwarf would be tidally locked. Planets migrate a lot, for various reasons, which invalidates the basic premise underlying a significant chunk of this section. When discussing speculative hypotheses, it is still best to avoid making wild assumptions wherever possible.-- (talk) 03:24, 11 October 2013 (UTC)

Both the section and your comment aren't backed by reliable sources. Adding and reworking the section with the help of sources is welcome. Face-smile.svg --cyclopiaspeak! 16:00, 11 October 2013 (UTC)

Less than a second[edit]

According to this recent edit, "If the history of Earth was compressed into one year, all currently existing plants and animals would not appear until less than a second." Assuming that means "... less than a second from the end of the year", that is plainly false: history of Earth=4.5x109years/3x107 seconds in a year=150 years. Even if "all currently existing plants and animals" means individuals not species, the oldest tree is much older. Is anything else in that paragraph worth saving? Art LaPella (talk) 01:10, 31 July 2014 (UTC)

NASA-TV (08/20/2014@5:30-6:30pm/et/usa) - Habitable Exoplanets.[edit]

FWIW - NASA-TV (08/20/2014@5:30-6:30pm/et/usa) - panel of experts discuss ancient Earth and Habitable Exoplanets< ref name="NASA-20140819">Brown, Dwayne (August 19, 2014). "MEDIA ADVISORY M14-137 - NASA to Air Panel Discussion about Ancient Earth and Habitable Planets". NASA. Retrieved August 20, 2014. </ref> - Enjoy! :) Drbogdan (talk) 13:53, 20 August 2014 (UTC)

FOLLOWUP - NASA VIDEO REPLAY - Excellent imo - Space Experts Discuss "Ancient Earth, Alien Earths" (59:38) at => - Enjoy! :) Drbogdan (talk) 23:53, 20 August 2014 (UTC)