Goldilocks Zone: A Widened Definition

[Nigle Amar]

Based on the wildly diverse adaptations that life on Earth has managed to accomplish, the current search for planets in the "Goldilocks" zone is to restrictive as to the type of circumstances that are required for a "Goldilocks" environment. Such zones may be found in any semi-stable environment where there is a transition from "to hot" to "to cold". Using this basis I believe that it will be discovered that our solar system has many "Goldilocks" zones. To begin with, why wouldn't Venus, Saturn, Jupiter, Uranus, & Neptune not have such zones? They all have "to hot" enteriors while their outer atmospheres being "to cold". Yes, there is vigorous (if not violent) vertical mixing but I think we are under estimating life's adapability & ability to find niches. The same holds true for tidally locked planets and moons that are "to hot" on one side & "to cold" on the other. Should there not be a "Goldilocks zone" somewheres inbetween? One argument is that a lack of atmosphere or a violently interacting atmosphere would eliminate the possibility of life. But you don't need an atmosphere to sustain life (see Earth life). It is might even be possible that our moon has a "Goldilocks zone" at the poles where perpetual darkness transitions to sun warmed surfaces.

 

[H2Bro]

The Goldilocks zone refers to, I believe, an area where water can remain in a liquid form without boiling away or freezing completely. This is usually depicted as a certain radius away from the Sun, though its true there can be many such zones like at the night/day boundary of mercury or inside Titan. However, I think the goldilocks zone is a helpful rubric for general searches for life, as the types of elements and materials found in smaller rocky planets (carbon, nitrogen, silicon, iron, etc) also tends to group closer to the sun than outer planets composed mainly of gasses. I think this is owing to the sorting of various elements during planetary formation by way of accretion disc rotation though I am not 100% sure.

To be fair, it may also be incorrect that life needs liquid water / rocky planets and their elements like carbon etc to develop.

 

[Radrook]

So all we need to do is set up different goldilock zone conditions in a laboratory in order to determine the probability of each one producing life based on the results we get.

 

[H2Bro]

Yes, but that experiment might take millions of years to run. There has been experiments mixing basic elements in a sealed environment with inputs of solar radiation and electricity. ended up producing basic amino acid blocks and other organic compounds, pretty much spontaneously.

Best way to find signs of life is spectroscopic analysis of atmospheres looking for oxygen. Oxygen is highly reactive and naturally binds to other elements unless actively replenished by other processes, i.e. oxygen exhaling plant biosphere for example.

 

[Drakkith]

Per wikipedia:

In astronomy and astrobiology, the habitable zone is the region around a star where a planet with sufficient atmospheric pressure can maintain liquid water on its surface.

The terms "ecosphere" and "Liquid Water Belt" were introduced by Hubertus Strughold and Harlow Shapley respectively in 1953.[2] Contemporary alternatives include "HZ", "life zone", and "Goldilocks Zone."

As you can see, the goldilocks zone isn't about whether life can survive, but about whether liquid water can exist. While planets in the goldilocks zone aren't the only possible source of life, they represent what most people think as the best candidates.

 

[H2Bro]

I would bet numerous other factors can be included apart from the phase of water. A good bet might be background radiation from nearby astronomical activity, i.e. the very center of galaxies might be too radioactively hot for stable organic compounds (or, had life moved there, result in runaway mutations). But conversely, might there be an additional "goldilocks" zone around the galactic core that favors more rapid evolution as a result of increased background radiation?

 

[Drakkith]

Absolutely. From the same article I linked above:

"Habitable zone" is sometimes used more generally to denote various regions that are considered favorable to life in some way. One prominent example is the Galactic habitable zone' (the distance from the galactic centre).

 

[Nigle Amar]

LOL check out link to Jan 16 story

http://www.physorg.com/news/2012-01-re-thinking-alien-world.html

 

[Ryan_m_b]

Whilst life could theoretically exist in a variety of non-liquid water environments we do not yet have a comprehensive theory of abiogenesis for this planet, let alone coming up with some for planets with radically different conditions. Until such time that we have some indication of conditions other than those similar to Earth that are likely to give rise to life we might as well stick to what we know.

There is also the non-hard-science angle to think about; is research more or less likely to get funded/attract public attention if it is looking for conditions similar to Earth or conditions different? It may sound pedantic but it is an important consideration. Having headlines along the lines of "Earth-like planet with liquid water and possible oxygen atmosphere discovered" regularly appearing will keep the public more interested (and willing to have their taxes invested) than "Yet another gas-giant discovered"

 

[Nigle Amar]

Good Point!

 

[Chronos]

Gravitational locking is a concern with planets orbiting cool [less than K] stars. The habitable zone is too close to 'mommy' to avoid this effect long enough for advanced life forms to evolve.