LibriumArcana.Games

We can take 'em all on!

Seriously though, I thought Mars was bigger than that. Shows you what I know.

Pcm979 wrote:We can take 'em all on!

Seriously though, I thought Mars was bigger than that. Shows you what I know.

Mars is being theorized as originaly been a moon. Since it lacks a proper core. But it is still theory.
http://en.wikipedia.org/wiki/Mars

Holy shit that makes this place look small. And as a human being in a decent society I have only 2 questions...

1. How far away is it?
2. Is it worth the trip?(resources, suitable habitat, cool new races or tech?)

The Village Idiot wrote:Holy shit that makes this place look small. And as a human being in a decent society I have only 2 questions...

1. How far away is it?
2. Is it worth the trip?(resources, suitable habitat, cool new races or tech?)

Huh? Who, what, where?

By the way, if you really want to feel small, watch "Powers of Ten" or "Cosmic Voyage".

Hotfoot wrote:

The Village Idiot wrote:Holy shit that makes this place look small. And as a human being in a decent society I have only 2 questions...

1. How far away is it?
2. Is it worth the trip?(resources, suitable habitat, cool new races or tech?)

Huh? Who, what, where?

By the way, if you really want to feel small, watch "Powers of Ten" or "Cosmic Voyage".

betleguice is roughly the size of the dyson sphere in tng. though it's orbit would bebeyond mars(closer to the astroid belt), if taken to the extreem.

Damn, Antares is huge.

Scottish Ninja wrote:Damn, Antares is huge.

i'd say a dyspon sphere with the orbit of jupiter at low end to saturn at extreem though it could be bigger.

Wikipedia agrees. No, Antares isn't exactly tiny.

Doesn't the size of those things mean they're older than Sol?

And could they have an inhabitable planet in their orbits?

frigidmagi wrote:Doesn't the size of those things mean they're older than Sol?

As Antares is a Red Giant I'd say the answer in that case at least is a definite yes.

And could they have an inhabitable planet in their orbits?

I don't see why not.

I'm wondering because of the sheer age and size of the stars invovled. A inhabitable planet by our standards would have to orbit alot farther away from Antares than we do from Sol wouldn't it?

frigidmagi wrote:I'm wondering because of the sheer age and size of the stars invovled. A inhabitable planet by our standards would have to orbit alot farther away from Antares than we do from Sol wouldn't it?

It would at that but I don't see that as a problem. As long as a planet is in the 'habitable' (as we define it) zone of a solar system, who cares how far out that zone actually is?

Well my understanding is that stars don't start out as red gaints. They expand into that. That means the habitable zone would have moved and any planet in the old one would likely have been destoryed. Since rocky planets don't seem to hang in the outter rims of the solar systems, that means that new planets have to be caught into the gravity pull or formed. Would a red giant last that long?

Something else to remember is a Red Giant is much much colder than a star like our Sun. I doubt that a Red Giant would still have a habitable zone, because of what frigidmagi just said, but I don't know for sure.

The Wikipedia article I linked gives Antares 65,000 times the luminosity of Sol and a lot of that is IR so I don't think the heat issue is going to be much of a problem.
The question is can Earth-size planets form where our solar system has gas giants/overambitious moons, and will they have the time to develop ecosystems.

Ali Sama wrote:i'd say a dyspon sphere with the orbit of jupiter at low end to saturn at extreem though it could be bigger.

It is about 3.7 AU in radius, which is about 3/4 the way out to Jupiter from the sun. That is HUGE. Its mass is about 15 times that of the sun, which makes it significantly less dense than the sun, which is to be expected, considering it is near the end of its life, and has under gone significant expansion.

Betelegeuse is also gigantic, about 650 times the radius of the sun, and about 15 times more mass. That would go past the asteroid belt. Again, HUGE.

Stars are awesome.

Batman wrote:The Wikipedia article I linked gives Antares 65,000 times the luminosity of Sol and a lot of that is IR so I don't think the heat issue is going to be much of a problem.

That is because it is way, way bigger. Let's do the math.

The luminosity of the sun (power output) is about 2.8 x 10^26 watts.
Antares is about 10,000 times more, which comes out to ~2.8 x 10^30 watts. (Awesome fact: it would take still over 100 seconds absorbing all the energy emitted from this star to give the energy for one Death Star lower limit blast or over 3 years for an upper limit shot!)

What we want to determine is a formula so we can see watts / square metre at any given radius from the star's surface.

The surface area of a sphere equals four pi times the radius squared. If we divide the luminosity by this number, we get what we want.

So power per area = P / 4 pi r^2, where P is total power (luminosity) and r is distance from the centre of the star.

First, lets look at the power the sun puts out to earth. Earth is 150 million kilometres away from the sun, so lets plug in the numbers. The radius of the sun is negligible here (about 2.1 x 10^4 metres).

2.8 x 10^26 watts / (4 * 3.14 * (1.5 x 10^11 metres) ^ 2) equals about one kilowatt per square metre.

Lets find out what the radius would have to be around Antares for that same number of power.

First, apply a little algebra to get 1 x 10^3 * 4 * 3.14 * x^2 = 2.8 x 10^30, solving for x. Dividing and taking the square root to solve for x yields

x = sqrt(2.8 x 10^30 / ( 10^3 * 4 * 3.14)). Solving gets us 1.5 x 10 ^ 13 metres, which is 100 times farther out than the earth from the core. This result should not be surprising; the inverse square law of fields in physics is derived from the surface area of a sphere.

Let's see how far away from Antares' surface that is. Antares' radius is 3.7 AU, which is 3.7 x about 150 million kilometres, which ends up being 5.55 x 10 ^ 11 metres. We need to be 1.5x10^13 metres away from the core. Subtracting gives 1.4 x 10^13 metres away from the star's surface. That is about 96 AU out.


Armed with that number, let's see how long a year would be on this hypothetical planet. Orbital period is defined as

2 pi * sqrt(a^3 / (GM))

where a = the radius (actually, the semi-major axis of the ellipse, since orbits are indeed ellipses and not circles, but I will simplify here for the ease of our estimation)

G = the gravititional constant of the universe (6.7 x 10^-11 N m^2 Kg^-2)

and M = mass of the star. (Mass of the planet is negligible for this calculation)

Mass of Antares is about 3 x 10 ^ 31 kilograms.

Let's plug in.

2 * pi * sqrt((1.4 x 10^13)^3 / (6.7 x 10^-11 * 3 x 10 ^ 31))

= 7.3 x 10^9 seconds, which is about 200 earth years! Damn, that would be a long winter.

I'll leave it to the biologists here to say what effect such a long year (and consequently long summers and winters) would have on life devloping or surviving on such a planet.

These super giant stars only have a short lifespan, don't they? A few tens of millions of years, not anywhere near enough time for life to evolve.

I suppose some intelligence could come a long and use a planet in whatever the habitable zone currently is, but that would only be viable for a short while.

Also a good picture. Dayum big.

A few million years would not seem a short time to a intelligent specis unless they were truely dramatically different from us in terms of lifespan and view of time.

Consider that humanity hasn't even existed for half a million yet.

JEAP wrote:These super giant stars only have a short lifespan, don't they? A few tens of millions of years, not anywhere near enough time for life to evolve.

Aye, less than that often, since they are already near the end of their lives. They usally die well though, as a supernova.

As we have already investigated with the size, and planet in the habitable zone before it becomes a giant would be swallowed up when it becomes a giant. Picking up a new planet in the new habitable zone might be possible, but one being the right size would be unlikely, and there would be insufficent time for intelligent life to evolve from scratch there (maybe very primitive life might though; I don't know).

With the habitable zone so far out, making years so long, as I showed last post, I really don't think life could survive around a giant, even if it was brought there by act of Q or whatever. Artificial climates would probably be possible on this planet (heat to survive long winters), but life capable of creating artificial climates would have to be brought in from somewhere else. Doesn't look good.

Destructionator XV wrote:

Ali Sama wrote:i'd say a dyspon sphere with the orbit of jupiter at low end to saturn at extreem though it could be bigger.

It is about 3.7 AU in radius, which is about 3/4 the way out to Jupiter from the sun. That is HUGE. Its mass is about 15 times that of the sun, which makes it significantly less dense than the sun, which is to be expected, considering it is near the end of its life, and has under gone significant expansion.

Betelegeuse is also gigantic, about 650 times the radius of the sun, and about 15 times more mass. That would go past the asteroid belt. Again, HUGE.

Stars are awesome.

Yes they are. Their amazing.
this is what the wiki article said about the size. It was linked in the previouse posts.

Antares is a class M supergiant star, with a diameter of approximately 1.33 × 109 km, or if in place of our sun, it would slightly more than encompass the average orbit of Jupiter, and is approximately 600 light years from earth. Visually, its luminosity is about 10,000 times that of the Sun but overall, taking into account that the star radiates a considerable part of its energy in the infrared part of the spectrum the luminosity equals roughly 65,000 times that of the Sun. The mass of the star is calculated to be 15 to 18 solar masses. Its large size and relatively small mass give Antares a very low density.

Destructionator XV wrote:

JEAP wrote:These super giant stars only have a short lifespan, don't they? A few tens of millions of years, not anywhere near enough time for life to evolve.

Aye, less than that often, since they are already near the end of their lives. They usally die well though, as a supernova.

As we have already investigated with the size, and planet in the habitable zone before it becomes a giant would be swallowed up when it becomes a giant. Picking up a new planet in the new habitable zone might be possible, but one being the right size would be unlikely, and there would be insufficent time for intelligent life to evolve from scratch there (maybe very primitive life might though; I don't know).

With the habitable zone so far out, making years so long, as I showed last post, I really don't think life could survive around a giant, even if it was brought there by act of Q or whatever. Artificial climates would probably be possible on this planet (heat to survive long winters), but life capable of creating artificial climates would have to be brought in from somewhere else. Doesn't look good.

The problem is that the majority of the land would not be very fun to live in. The equadorial regions would be relativly comfprtable and be habitable however. I'd rather not live in a system like this. If earth ever where to reach it. We could put scientific reaserch facilites. An oneal cylinder would work perfectly.

you would ave a very nomadic ecology in a planet like that. It would be very pretty artistically. Giant floating habitats wihich can change locations based on the weather. though this is all speculation and scifi. rofl.

frigidmagi wrote:A few million years would not seem a short time to a intelligent specis unless they were truely dramatically different from us in terms of lifespan and view of time.

Consider that humanity hasn't even existed for half a million yet.

that is true. But you need time for the basic groundwork of life to begin. For that you need time for the planets to form, properly cool down. simple Life to evolve and florish. Then you can strart talking about mammels and other complex organisms.