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The article explains in length what Eyeball Planets are but gives little arguments why life should be more abundant there compared to other planets apart from a vague number argument.

Here are some reasons:


- Red dwarfs are by far the most common type of star in the Milky Way, at least in the neighbourhood of the Sun

- Red dwarfs exist for a long time (longer than ten billion years) which gives life a long time to spring into existence (or start via panspermia) and evolve

- Planets in the habitable zone of a red dwarf are tidally locked ("eyeball planets") due to their small distance to the star

So there is very likely to be a huge number of these types of planets with stable conditions over a long period of time.


Flares by the red dwarfs (which are not so rare) could destroy life on these planets

>Flares by the red dwarfs (which are not so rare) could destroy life on these planets

As a layperson, I'm curious how "bad" those flares are. Is it in the realm of possibility that life that develops on these planets could "hide" from these flares when they happen, or evolve defenses against them for when they happen? Or is it more "turn the surface into lava" kinds of events?

~100 times the intensity required to kill even the hardiest microorganisms, bad.


In the places that are exposed to the UV light.

You could have life that's 100m deep underwater, or living in protected structures (caves, etc). Life could evolve more protections against UV (e.g. some kind of carapace that the organism resides within).

Maybe the hard part is figuring out a way to use UV-heavy light to generate energy.

There is also the detectablility aspect. Closer planets mean shorter years which means we can detect them in a short time of observation. It's not that we don't want to find earth like planets, it is that it takes longer, so why not take the easy path even if the planets are questionably habitable.

Eyeball planets are quite common, easier to detect, and potentially life bearing.

Not necessarily more abundant, just more within reach of our current tools.

It's possible they are more abundant, because (according to a post above), red dwarfs are by far the most common type of star in this part of the galaxy, and any habitable-zone planets around a red dwarf are most likely tidally-locked, meaning they'd be eyeball planets.

It isn’t that life should be more abundant, simply that Eyeball planets are easier to find. Because they have the capacity to have life (contain a Goldilocks region), that’s where we are most likely to find life first (given current technology). It is a numbers argument, but so is finding alien life in general.

I don't think it made that claim (The HN title appears somewhat incorrect) - just that we are primarily detecting what are likely to be eyeball planets, so if life is out there on any of the planets we are detecting, then it'll most likely be an eyeball planet.

It's a bit circular and not really saying anything useful, but at least it's not claiming what the HN title (nor your criticism) is saying

We are detecting planets that are close to their host stars because they are relatively easy to detect using current methods.

If a planet is closer to its star, it's more likely to be tidally locked. It can however also be in a spin-orbit resonance higher than 1:1.

Tidally locked planets have a greater range of distances they can be from the central star while having a habitable zone. Non-locked planets need to be at just the right distance.

As to which kind of planet we'll find life on, depends on whether tidally locked planets with habitable zones are more frequent than non-tidally locked planets in a habitable orbit. I don't know that we know the numbers here.

> Non-locked planets need to be at just the right distance.

We are learning that there are liquid oceans all over our solar system so I'd argue that the classic concept of a habitable zone is outdated because it doesn't take them into account.

The habitable zone doesn't mean "anything inside supports life, everything outside doesn't".

It specifically means "the light from the planets sun is in the range to support surface-level life".

If a distant moon in our solar system has a liquid ocean that A) doesn't mean it's water or anything else sane and B) that habitable zones are poorly defined.

Liquid oceans generated by orbital- or geothermal activity aren't covered in the habitable zone definition and aren't very useful as they usually require a parent body to provide energy to heat the ocean (jupiter for example) but just not enough to boil it off the moon.

That's not what it says. Or at least it's not what the article says; the title is a bit dodgy. It's saying that the early habitable zone planets we're currently finding are likely tidally locked, because they're easier to find with current observational techniques.

So, how exactly is evaporation to outer space less of a problem in these red dwarf systems? Shouldn't eyeball planets suffer of that depletion especially?

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