Sybarite: Whew, just made it.

[i.space.com image 775x480]

I wonder why those are not straight lines. Maybe radiation from the parent star also has something to do with it.

simplicimus: Apparently Earth is outside the habitable zone, at the zone begins at .99 AU.

We get as close as 0.98329134 AU.

But that's when the Zombies come out.

MindStalker: simplicimus: Apparently Earth is outside the habitable zone, at the zone begins at .99 AU.

We get as close as 0.98329134 AU.

But that's when the Zombies come out.

Facebook AU burn



Dont tell me I'm wrong ever again!

Farker Soze: MindStalker: simplicimus: Apparently Earth is outside the habitable zone, at the zone begins at .99 AU.

We get as close as 0.98329134 AU.

But that's when the Zombies come out.

Facebook AU burn



Dont tell me I'm wrong ever again!

Came here for the "10 ft difference and we'd die" reference. Leaving satisfied.

/I always wondered what people who believed that thought about two story buildings and ladders

As an aside, anyone else getting autoplay videos on fark now?

According to my calculations, we're actually outside the habitable zone right now.

...oh my god.... WE ARE THE THINGS THAT SHOULD NOT BE! (deep breath) AAAAAAAAAAAAAAAAAAAAAAAAAAA! (breathes) AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA!

Mars is no place to raise your kids.

I wonder how much of this is going to turn out to be complete rubbish.

Why is liquid water necessary for life? Isn't this a paradigm? Of course a solvent medium is best for bringing together the ingredients necessary for the right chemical reactions to occur, so some form of liquid on the surface is likely necessary, but why couldn't there be an entire ecosystem that arises based on ammonia? It is a polar solvent, like water. Reactions might take longer at colder temperatures, but this would only mean that life would take a billion years to evolve to the same extent as 100 million earth years.

Jubeebee: simplicimus: Apparently Earth is outside the habitable zone, at the zone begins at .99 AU.

That's kind of how I read this too. The earth's orbit is sufficiently elliptical that I would think we spend a good part of the year farther out than 0.99AU.

I am surprised Venus isn't in the habitable zone though. I thought Venus would be a nice place if not for all of the carbon mon/dioxide and sulfuric acid in the atmosphere.

That was the general sentiment for many years, but the last probe we sent to Venus lasted just long enough to tell us that things were a little on the hot side. Then it melted.

Millennium: Jubeebee: simplicimus: Apparently Earth is outside the habitable zone, at the zone begins at .99 AU.

That's kind of how I read this too. The earth's orbit is sufficiently elliptical that I would think we spend a good part of the year farther out than 0.99AU.

I am surprised Venus isn't in the habitable zone though. I thought Venus would be a nice place if not for all of the carbon mon/dioxide and sulfuric acid in the atmosphere.

That was the general sentiment for many years, but the last probe we sent to Venus lasted just long enough to tell us that things were a little on the hot side. Then it melted.

But wouldn't that be due to the runaway greenhouse effect?

If people wanna hear about space, I'ma rhyme about PLU-TO.

Farker Soze: MindStalker: simplicimus: Apparently Earth is outside the habitable zone, at the zone begins at .99 AU.

We get as close as 0.98329134 AU.

But that's when the Zombies come out.

Facebook AU burn

[scienceblogs.com image 471x543]

Dont tell me I'm wrong ever again!

If you could reason with religious people, there'd be no religious people.

"There is a fifth dimension beyond those known to man.  It is as vast as space and as timeless as infinity.  This is the dimension of imagination.  It is the area we call..."

/the "what zone," now?

Tommy Moo: Why is liquid water necessary for life? Isn't this a paradigm? Of course a solvent medium is best for bringing together the ingredients necessary for the right chemical reactions to occur, so some form of liquid on the surface is likely necessary, but why couldn't there be an entire ecosystem that arises based on ammonia? It is a polar solvent, like water. Reactions might take longer at colder temperatures, but this would only mean that life would take a billion years to evolve to the same extent as 100 million earth years.

You are absolutely right, it doesn't necessarily have to be water.  Ammonia and water are both protic solvents and in fact life as we know it (from a biochemistry stand point) could have developed in either.  Our biochemistry is just much more efficient in water (the argument of cause-or-effect/chicken-or-egg can be left up to others).  The fact that both ammonia and water can donate and accept protons is the key.  In a similar fashion, there could even be a whole ecosystem based in ethanol; perhaps called fark.

One of my students today let slip that he wanted to build a Death Star so he could put Pluto out of its misery. I warned him that some people (like Stubby) are emotionally attached to that little thing.

ReverendJasen: simplicimus: Ok. but upthread some noted we occasionally get close to 1 AU, but not quite. Maybe better measurements have changed the distance between Earth and Sun?

What they meant by that is that our orbit is elliptical (oval) but because an AU is a fixed number, it would be represented as a perfect circle around the sun, so most of the time we're closer than 1 AU, some of the time we're farther than 1 AU, depending where we are at any given moment.  1 AU was defined as the average between our closest point and farthest point.

To be specific, aphelion is ~1.017 AU and perihelion is ~0.983 AU.  Honestly, they probably should have made the habitable zone for the sun at least closer than the closest we get.


Jubeebee: machoprogrammer: Millennium: Jubeebee: simplicimus: Apparently Earth is outside the habitable zone, at the zone begins at .99 AU.

That's kind of how I read this too. The earth's orbit is sufficiently elliptical that I would think we spend a good part of the year farther out than 0.99AU.

I am surprised Venus isn't in the habitable zone though. I thought Venus would be a nice place if not for all of the carbon mon/dioxide and sulfuric acid in the atmosphere.

That was the general sentiment for many years, but the last probe we sent to Venus lasted just long enough to tell us that things were a little on the hot side. Then it melted.

But wouldn't that be due to the runaway greenhouse effect?

That's what I was getting at. I was under the impression that if Venus had a nitrogen based atmosphere like Earth it would be habitable. But there's the greenhouse effect instead. Plus the sulfuric acid.

It would still be pretty nasty, probably like a giant desert, one big Death Valley.  Even worse really, because a single day on Venus is 243 Earth days long, which means 121 days or so baking in the sun followed by 121 days freezing in the night.  Would likely be a more hospitable place than the moon though.

SnarfVader: Sybarite: Whew, just made it.

[i.space.com image 775x480]

I wonder why those are not straight lines. Maybe radiation from the parent star also has something to do with it.

Note the log scale on the bottom (and maybe on the left, it isn't too clear exactly what the scale is), if it was on a linear scale it would look very different (and much bigger to get any visible width at the bottom of the scale.

SnarfVader: Sybarite: Whew, just made it.

[i.space.com image 775x480]

I wonder why those are not straight lines. Maybe radiation from the parent star also has something to do with it.

Hard to tell without a scale on the y-axis.  I kinda wonder which regime is the simple r^2 one.  The steeper one is probably an r^3, where the biggest factor is tidal forces.  No idea if they also took into account how the planetary disk of different types of stars accrete during planetary formation.  Some tend to form with more rotational energy, which would make it harder to planets to keep hold of an atmosphere.

So as far as the intergalactic community is concerned, we humans are a rugged ice people from a frozen world. Feels like it in northern Indiana today.

Err... Just the opposite. We're from a super hot planet that's nearly boiled off. That... Doesn't seem right, unless global climate change really is the end of the world. I don't like the sound of this new habitable zone. It seems nonsensical, unless there are some very quirky things keeping our planet cool in their model.

Meh, I'm with one of the commenters on TFA. The habitable zone is a relatively narrow band from 0.99 AU to 1.67 AU for a Sol-type star, assuming:

...that all our knowledge about atmospheric dynamics applies to other planets. Oh, except they say they don't even consider clouds, so never mind, I guess.

...that "liquid water is stable on the planetary surface" is a hard and fast requirement for life. Never mind Earth's own deep biosphere, or all those microorganisms we've just found in the stratosphere, or deep-sea vents, etc, etc.

...that moons orbiting gas giants, heated by tidal effects and perhaps even by thermal radiation from the gas giant itself, don't count.

...that Earthly biochemistry, with our particular fragile proteins and sugars, is the only possible path to life.

...that life even needs to be water-based. Ammonia-based lifeforms shudder at the thought of an environment saturated with toxic, corrosive hydroxylic acid. Critters who've evolved from the rich, dynamic environment of a stellar convective zone probably aren't even aware of such extreme low-temperature phenomena as "chemistry".

jfarkinB: sugars

To be fair, photosynthesis is awesome because it's apparently 100% efficient at turning photons into stored energy.  So I could see that happening in a lot of places.

Skirl Hutsenreiter:

SnarfVader: I wonder why those are not straight lines. Maybe radiation from the parent star also has something to do with it.

Hard to tell without a scale on the y-axis.

I think it's log-log with stellar mass on the y axis. See Fig. 15 of this paper. Log-log produces some nonlinearity but won't turn a linear function into something with these kinds of inflection points. There are all kinds of nonlinearities in the problem, though, if you look through the other figures in the paper. There are nonlinearities in the mass-luminosity relation, in the water vapor response to solar flux, in albedo as a function of solar flux, etc. Also the figure probably refers to the continuously habitable zone, whose boundaries depend on stellar luminosity-age relationships as a function of mass.

simplicimus: If we were a species capable of long term thinking, we could probably start seeding theatmosphere of Venus  to make it more hospitable in the  distant future.

given that venus is tidally locked, or nearly so, to the sun... i really would rather not visit.

i could see leaving it as-is however, and building masses of dirigibles in the upper atmosphere, above the clouds. oxygen is a lifting gas on venus, after all, and about 66 miles up it's pretty comfortable temperature wise.

the winds are a stone biatch tho. have to come up with something to deal with those.

Not sure if mentioned since time is limited, but Tidal forces play a big part in the liquidity of water. It's why we're looking at Europa and other moons of our outer gas giants. Internal heat through friction of simply changing shape from nearby gravity plays a major role in the temperature of a body. Looking at gravity-only scenarios, the Goldilocks zone seems like a great idea for smaller Earth-like planets with roughly circular orbits within a distance range that rely on solar energy. But larger bodies in closer proximity could be in a binary configuration, each spinning, that via the inverse square law deforms each body over time in its rotation enough to generate sufficient internal heat. Neither one has to be a star.

aerojockey: I came here to call shenanigans, but I see it's been covered.

Earth is closer than 0.99 AU, outside the supposed "habitable zone", in July at least.  So if the Earth were to orbit the sun at the distance it is during July for the whole year, all the water would evaporate?  Sure.

No it isn't. Earth is farther away from the sun in July than at any other time.

Shazam999: jfarkinB: sugars

To be fair, photosynthesis is awesome because it's apparently 100% efficient at turning photons into stored energy.

Unfortunately not:

Photosynthetic efficiency

Tommy Moo: Why is liquid water necessary for life? Isn't this a paradigm? Of course a solvent medium is best for bringing together the ingredients necessary for the right chemical reactions to occur, so some form of liquid on the surface is likely necessary, but why couldn't there be an entire ecosystem that arises based on ammonia? It is a polar solvent, like water. Reactions might take longer at colder temperatures, but this would only mean that life would take a billion years to evolve to the same extent as 100 million earth years.

It is not that water is the only possibility for supporting life, just that we know life exists based on water, and we know what it looks like, and some of the conditions that allow it to develop. It's a lot easier to find something when you know what you're looking for.

Not only is there nothing to say that non-water based life may develop, but even water-based life may develop in ways we're not looking for. The habitable zone only applies to the possibility of surface water, but a variety of conditions may allow for water below the surface, or so tightly controlled by the ecosystem that it (in liquid form, at least) exists only within that ecosystem, or even for surface water to exist outside the habitable zone because of the planet's other unique characteristics.

I shouldn't say we know what it looks like, but rather we know what the conditions look like.

aerojockey: I came here to call shenanigans, but I see it's been covered.

Earth is closer than 0.99 AU, outside the supposed "habitable zone", in July at least.  So if the Earth were to orbit the sun at the distance it is during July for the whole year, all the water would evaporate?  Sure.

You sound like a science teacher.

Tell me again about how Noah forgot to feed the dinosaurs that were on the ark causing them to eat each other all up.