<p>Nothing that complex. Habitable zone merely defined a circumstellar volume where a planet (if any) can receive an amount of radiative energy to keep H<sub>2</sub>O in the liquid phase.</p>

<p>Yes, it has been based on the requirements for life from Earth, lacking any wider samples.</p>

<p>I encourage you to play around with <a href="http://astro.unl.edu/naap/habitablezones/animations/stellarHabitableZone.html" rel="nofollow">interactive illustration</a> of concept (Flash applet).</p>

CC BY-SA 3.0
2014-12-23T11:16:14.060Z
But it is dependent on assumptions about the atmosphere, isn't it? There's no liquid water on the Moon, which is as much in an HZ as Earth is. And Venus completely lacks water, it seems to be the very driest of all planets.
LocalFluff
CC BY-SA 3.0
2014-12-23T13:11:49.603Z
@RhysW, if there is a demand for the complex answer, I could add an another post, but it will be a very vague one since there are numerous studies and numerous assumptions about HZ which (IMO) reduces a confidence in the whole concept.
Free Consulting
CC BY-SA 3.0
2014-12-23T13:19:47.097Z
@Evert Oh, a special case ;p Unlike all of the other standard planets, like... ehm.
LocalFluff
CC BY-SA 3.0
2014-12-23T16:07:11.140Z
"receive an amount of radiative energy to keep H2O in the liquid phase" On the *surface*. Ice-moons with tidally heated inner seas, like those around Jupiter, need not fall in the Goldilocks zone in order to support life.
Wayfaring Stranger
CC BY-SA 3.0
2014-12-23T19:02:09.463Z
@Evert I don't want to be obnoxious on the HZ-issue, I have no better definition myself. But I think that it should be reminded that our nearest two bodies, the Moon and Venus, show us what huge spread is possible even within the habitable zone. And how do they know that they have found any exoplanets at all? Aren't they maybe exo-**dwarf**-planets according to the new definitions of the IAU? And on that issue I do confess that I am a bit obnoxious, but only because they started it!
LocalFluff
CC BY-SA 3.0
2014-12-23T20:30:38.833Z
@LocalFluff, the inner edge of so called "consevative HZ" (`0.725AU`) lies about Venus's orbit with aphelion in and perihelion out, so it's pretty marginal even without taking greenhouse effect into account (and I'd really like to avoid that, because it extends the outer edge toward ridiculous distance `>2AU`).
Free Consulting
CC BY-SA 3.0
2014-12-23T21:40:30.963Z
@Evert, exactly. Conservative HZ concept is practical for selecting area of interest and doesn't relies on too many assumptions... as while transit method can give us a few information about exoplanet's atmosphere, we have no tools at all for assessing exoplanet's albedo.   Meanwhile, I see Titan as highly special case because it [orbits near huge cyclotron](http://astronomy.stackexchange.com/a/8351/4108).
Free Consulting
CC BY-SA 3.0
2014-12-23T07:20:44.530Z
2014-12-23T12:46:16.567Z
2014-12-23T12:46:16.567Z
Free Consulting
<p>I've a question on Habitable zone.</p>

<p>Does Habitable zone represent the region where we humans or the living beings of earth can survive?</p>

<p>Or is it a region where life can exist?</p>

<p>If it is second I want to know what are the parameters that are considered for existing of life. </p>

<habitable-zone>
What is the Habitable zone all about?
Strikers
# What is the Habitable zone all about?

(Asked by: username_0 on 2014-12-23)

I've a question on Habitable zone.

Does Habitable zone represent the region where we humans or the living beings of earth can survive?

Or is it a region where life can exist?

If it is second I want to know what are the parameters that are considered for existing of life.

**Tags:** habitable-zone


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## 1 answers

### Answer by username_1 on 2014-12-23. Score: 2

Nothing that complex. Habitable zone merely defined a circumstellar volume where a planet (if any) can receive an amount of radiative energy to keep H2O in the liquid phase.

Yes, it has been based on the requirements for life from Earth, lacking any wider samples.

I encourage you to play around with [interactive illustration](http://astro.unl.edu/naap/habitablezones/animations/stellarHabitableZone.html) of concept (Flash applet).

> **Comments:**
> **username_2**: But it is dependent on assumptions about the atmosphere, isn't it? There's no liquid water on the Moon, which is as much in an HZ as Earth is. And Venus completely lacks water, it seems to be the very driest of all planets.  
> **username_1**: @RhysW, if there is a demand for the complex answer, I could add an another post, but it will be a very vague one since there are numerous studies and numerous assumptions about HZ which (IMO) reduces a confidence in the whole concept.  
> **username_2**: @Evert Oh, a special case ;p Unlike all of the other standard planets, like... ehm.  
> **username_3**: "receive an amount of radiative energy to keep H2O in the liquid phase" On the *surface*. Ice-moons with tidally heated inner seas, like those around Jupiter, need not fall in the Goldilocks zone in order to support life.  
> **username_2**: @Evert I don't want to be obnoxious on the HZ-issue, I have no better definition myself. But I think that it should be reminded that our nearest two bodies, the Moon and Venus, show us what huge spread is possible even within the habitable zone. And how do they know that they have found any exoplanets at all? Aren't they maybe exo-**dwarf**-planets according to the new definitions of the IAU? And on that issue I do confess that I am a bit obnoxious, but only because they started it!  
> **username_1**: @username_2, the inner edge of so called "consevative HZ" (`0.725AU`) lies about Venus's orbit with aphelion in and perihelion out, so it's pretty marginal even without taking greenhouse effect into account (and I'd really like to avoid that, because it extends the outer edge toward ridiculous distance `>2AU`).  
> **username_1**: @Evert, exactly. Conservative HZ concept is practical for selecting area of interest and doesn't relies on too many assumptions... as while transit method can give us a few information about exoplanet's atmosphere, we have no tools at all for assessing exoplanet's albedo.   Meanwhile, I see Titan as highly special case because it [orbits near huge cyclotron](http://astronomy.stackexchange.com/a/8351/4108).  

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