The Sun

[rens14]

It dosent really take much change for a sun to make a habitable planet inhabitable. Just a change of 5-10 degrees would be enough to kill everything. And once the plants and oceans are gone its just a matter of time before a planet goes to sand. Look at it like Earth into Mars into a giant sand ball into a steaming molten rock then its swallowed by its sun. Venus is in the other direction, like earth long before it became habitable through changing enviromental factors and the huge impact of emerging bacterial life.

I agree because 15.000 years ago we had an ice age so earth so without changes in the sun so small changes in the sun can have very big effects on a planets

[Mitchell82]

I'm no astronomer, but doesn't the evolution of a star take place on the timescale of millions and billions of years and not 48,000? The star should not have been able to drastically change the planet to such an extent in such a small period of time. And only an additional 500 years to completely remove the atmosphere sounds even more suspect.

I still enjoyed the episode though.

If it evolved naturally yes. But there are many things that could cause a problem with the natural evolution of the sun.

[Demerzel]

It comes down to this.

We don't know the age of the current planet's sun at the time that Atlantis settled down on it. If when Atlantis arrived, the sun was already near turning into a red giant, then 48,000 years could be realistic period of time. There is also the factor of how far away the planet is from the sun.

To give an example, our sun will turn into a Red Giant in 5-6 billion years, and it's already 4.57 billion year old. So either the sun in Atlantis's solar system is reaaaaally old, considering the universe itself is 13.7 billion year old, or the writers again are showing their ignorance when it comes to astronomy.

There's no easy answer to this one, we don't have enough details to come to a decent conclusion.

[SP90]

Glad someone decided to start this thread. I also found it confusing how the star in the Atlantis system can change so suddenly. I mean 48,000 years is like a blink of an eye relative to the age of a normal G type star like that. It would have been more plausible if they said something shifted the orbit of the planet like in ST:II. That being said, it is sci-fi. If the Asgard can artificially increase the mass of a star and turn it into a black hole then maybe someone found a way to speed up the rate the Atlantis star consumes it's fuel supply.

[PG15]

Assuming the star was of average mass and age (compared to our own Sun), it can be somewhat safe to assume then, it should be about 1/2 way through its life time of about 10 billion years. Being transported 48,000 years into the future is not going to make the star into a super giant, nor would it have boiled off all the planets water.

Unless, of course, the star formed 10 billion years ago, which would mean that it's nearly 100% though its main-sequence life time. Not all stars formed at the same time as the sun.

If the star was already approaching the super giant phase, the planet would not have been hospitable to life when Atlantis landed on it earlier this season. Our own planet will most likely become inhospitable to life in only a billion years - well before the red giant stage (in five billion years) becaue the Sun is burning hotter as it consumes the last of it fuel.

Unless, of course, that this planet WASN'T hospitable a few billion years ago, and only got its oceans when the sun grew hot enough so that the habitable zone extended to where the planet was. This, I think, is the crux of the matter that you forgot to think about.

Or I'm completely wrong about this, whatever.

[Gate Geek]

Unless, of course, the star formed 10 billion years ago, which would mean that it's nearly 100% though its main-sequence life time. Not all stars formed at the same time as the sun.

Unless, of course, that this planet WASN'T hospitable a few billion years ago, and only got its oceans when the sun grew hot enough so that the habitable zone extended to where the planet was. This, I think, is the crux of the matter that you forgot to think about.

Or I'm completely wrong about this, whatever.

I know not all stars formed the same time as our Sun. But if the sun did form 10 billion years ago and its very near the end of its life, it would still have made the planet inhospitable long before this point.

I admit I'm not sure what you're getting at in the second paragraph. Could you please clarify for me.

Ack! My brain is tired of this science stuff. I'm gonna give it a rest.

[rob_squared]

I'm no astronomer, but doesn't the evolution of a star take place on the timescale of millions and billions of years and not 48,000? The star should not have been able to drastically change the planet to such an extent in such a small period of time. And only an additional 500 years to completely remove the atmosphere sounds even more suspect.

I still enjoyed the episode though.

There just might be a way to explain this, but it'd be kind of weird. Perhaps atlantis was moved to a different planet again, one that had sand dunes. Maybe after Rodney programmed the hologram it became necessary to hide atlantis on a world like that, one that had a red giant star but had a planet far enough away to become habitable. And as far as sheppard gating to the planet where atlantis used to be, someone from atlantis put a macro there and forwarded sheppard to where atlantis is in the future. The tricky part is explaining how they got sheppard forwarded back to atlantis once they used the flare to get him back to his current time. I'm having trouble justifying that part without using a generic time machine (for obvious reasons).

(fixing plot holes has become a hobby of mine)

[The_Carpenter]

Where is the mention of it being ice originally?

Vala,

It was in Alex Levines blog, I don't have a link unfortunatly it should be the latest entry

[Cory Holmes]

I admit I'm not sure what you're getting at in the second paragraph. Could you please clarify for me.

Earth exists in a narrow band of space where the heat energy of the sun is juuuuust enough to have liquid water. If Earth with a little closer, it'd be hot and all the water would boil away. A little farther, and it'd all be locked up in solid ice.

Now we know that a star's energy output will vary over time as it goes through it's life cycle. It's known that that our sun and it's habatibility range hasn't always been centred around Earth and that as it evolves out of the Main Sequence and into its later life that zone will expand outward as the sun does.

So what PG15 was trying to suggest that perhaps the planet that Atlantis landed on in Lifeline is farther out in its solar system and the primary star has already evolved into (or nearly into) the Red Giant phase. So that 48,000 years was enough time for the star to push that zone even farther out and wreak havoc on the planet.

In fact, that could be one reason why the A-Team ignored that planet when they were first searching for a new home, and only went to that when Weir was abducted by the Replicators.

[PG15]

Uh...yeah, what he said.

[Gate Geek]

Earth exists in a narrow band of space where the heat energy of the sun is juuuuust enough to have liquid water. If Earth with a little closer, it'd be hot and all the water would boil away. A little farther, and it'd all be locked up in solid ice.

Now we know that a star's energy output will vary over time as it goes through it's life cycle. It's known that that our sun and it's habatibility range hasn't always been centred around Earth and that as it evolves out of the Main Sequence and into its later life that zone will expand outward as the sun does.

So what PG15 was trying to suggest that perhaps the planet that Atlantis landed on in Lifeline is farther out in its solar system and the primary star has already evolved into (or nearly into) the Red Giant phase. So that 48,000 years was enough time for the star to push that zone even farther out and wreak havoc on the planet.

In fact, that could be one reason why the A-Team ignored that planet when they were first searching for a new home, and only went to that when Weir was abducted by the Replicators.

That's what I thought, but didn't want to assume wrong, respond and get blasted for it. It seems to happen alot in some threads. Better to ask for clarification first.

That scenario could work. But the planet would have to pretty damned far out though. If I think of our solar system and our sun, our sun when it reaches the red giant phase will swallow up the orbits of Mercury and Venus and nearly extend to Earth. The possible habitable area in our Solar System then would be some of the moons of Jupiter or Saturn which currently show strong evidence of oceans of water covered by layers of ice.

You're right, habitable zones can come come and go and in be lots of different places as discovered in our own solar system (Mars mostl likely had liquid oceans of water on its surface in the past, Jupiter has moons with oceans of water underneath their surfaces - most likely their interiors being heated by the tug of Jupiter's gravity and there is evidence that some of Saturn's moons may have oceans of water as well.)

It's a pretty tight balancing act for a planet to be habitable and pretty damned amazing life exists at all.

[Vala_M]

It was in Alex Levines blog, I don't have a link unfortunatly it should be the latest entry

Thanks. I found it on Google.

Vala,

[ZixPax]

A star with mass 5x times the sun go through the following

6,44*10^7 yr Hydrogen burning in core(
2,2*10^6 yr Overall contraction phase
1,4*10^5 yr Establishment os shell source
1,2*10^6 yr Hydrogen burning in thick shell
8*10^5 yr Shellnarrowing phase
5*10^5 yr Red-Giant phase

The earht sun is in the Hydrogen burning core phase.

I think it showes that there may be a problem with the idea that the sun could go redgiant in 48.000.
simply because when increasing the mass you reduce the time it takes for the star to go from hydrogen burning in the core to redgiant you also reduce the time it take for the star to burn up all the hydrogen in the core.
And a planet dosen't form i a matter of years

[Cory Holmes]

There doesn't need to be a tremendous change in stellar output in order to affect a planet. If the Earth were orbiting as little as 5% closer or farther from the sun, then we wouldn't have the proper conditions to have all three phases of water present.

There had to be a reason why this world wasn't originally considered to be Atlantis' new home. Perhaps stellar instability or late-life had something to do with it.

[Blanche]

I just rewatched Echoes from season 3 and I had to think about TLM.

Maybe one of these corona blast things was responsible for heating up the planet and makeing the ocean a desert.
McKay said this stuff comes up kind of every 15,000 years, so it would have happend twice by the time shep arrives in the future