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Four Earth-sized planets detected orbiting the nearest sun-like star

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Re: Four Earth-sized planets detected orbiting the nearest sun-like star

#61

Post by neuromancer2701 »

sqeaky wrote: post #45
dmix wrote: post #36

Earlier quoted context omitted.

Is there a significant difference between a nuclear explosion in space compared to on earth? Would it be less powerful or offer greater thrust?

A nuclear explosion in space wouldn't push against the air and would expand spherically unless somehow contained. Because it doesn't use conventional chemistry the presence or absence of chemicals, like ambient oxygen wouldn't change the output (like it might for a fuel air bomb) but their their properties might change it. Air will provide some resistance and fluoresce at high enough temperatures. I am curious how bi…

If you have ever seen Ron D. Moore's Virtuality. They based the Phaeton off of Orion and it is pretty cool to see how it would work. They have a whole sequence of dropping the nukes behind the ship and the explosions pushing the massive pusher plate.

Re: Four Earth-sized planets detected orbiting the nearest sun-like star

#62

Post by utexaspunk »

baron816 wrote: post #37

Ok, let's assume we find a warm, watery planet like Earth's within ~20 light years, and we figure out a way to travel >= 50% the speed of light, making it somewhat reasonable to get there. If the planet's gravity is greater than 10% different from Earth's, or its Day/Night cycle is much different from Earth's, wouldn't it still be a nightmare to live on. Anatomically modern humans have lived on Earth for 200,000 year…

I don't know about the day/night thing, but we could definitely get used to more gravity. When coming in for landing you could decelerate over the course of the last year or so at a slowly increasing rate to an effect of slightly more gravity than the planet you're landing on. You slowly grow accustomed to that and then when you land, you actually feel lighter on the surface of the planet.

Re: Four Earth-sized planets detected orbiting the nearest sun-like star

#63

Post by semaphoreP »

swamp40 wrote: post #22
semaphoreP wrote: post #20

Earlier quoted context omitted.

I guess you're right. I know there aren't any observed transits, but I also don't know what the current constraints from monitoring the star's brightness for transit is (the star is actually so bright that it becomes hard to monitor for planet transits). However, we have a good prior on the inclination of these planets, because we know the inclination of the dust disk around the star ( https://www.scientificamerican.…

Since they are watching the star wobble, they probably have exact inclinations.

Measuring the star wobble (i.e. doppler shift) doesn't give inclinations.

Re: Four Earth-sized planets detected orbiting the nearest sun-like star

#64

Post by theseatoms »

alistproducer2 wrote: post #60
bwat49 wrote: post #51

Earlier quoted context omitted.

I'm sure it wouldn't be easy, but humans have proven to be very adaptable.

>proven to be very adaptable to conditions on Earth

Sure. And once we adapt to conditions on Planet X, we'll be hardly human.

Re: Four Earth-sized planets detected orbiting the nearest sun-like star

#65

Post by tadfisher »

hinkley wrote: post #28
swamp40 wrote: post #22

Earlier quoted context omitted.

Since they are watching the star wobble, they probably have exact inclinations.

Seems like it would have to be. If you've worked out from the wobble what the mass and orbit are it would stand to reason you've either calculated or at least stated an assumption regarding the inclination.

You can put a lower bound on both, but inclination introduces an unknown upper bound.

Re: Four Earth-sized planets detected orbiting the nearest sun-like star

#66

Post by semaphoreP »

BurningFrog wrote: post #23
eggpy wrote: post #12

Earlier quoted context omitted.

Can you say they _don't_ transit? They say the planets were detected by analyzing star wobbles, which doesn't necessarily mean that the planets don't transit, just that it's not how they were detected.

Yeah, but the Kepler observatory has looked for exoplanet transits for many years now and found over 1000. You have to assume it has examined this close neighbor thoroughly.

Actually this star is not in the Kepler Field, and it is also too bright for Kepler. Even most ground based telescopes looking for transits probably haven't bothered looking at it, due to its brightness.

Re: Four Earth-sized planets detected orbiting the nearest sun-like star

#67

Post by 1001101 »

alistproducer2 wrote: post #58
baron816 wrote: post #37

Ok, let's assume we find a warm, watery planet like Earth's within ~20 light years, and we figure out a way to travel >= 50% the speed of light, making it somewhat reasonable to get there. If the planet's gravity is greater than 10% different from Earth's, or its Day/Night cycle is much different from Earth's, wouldn't it still be a nightmare to live on. Anatomically modern humans have lived on Earth for 200,000 year…

I'm going to show my nerd colors here but having a thought like this has almost ruined Star Trek for me. For me I often think about atmospheric pressure. There's no way that beings from so many different planets could exist on a single star ship set at 1 Earth atmosphere. Maybe someone knowledgeable in this space can tell me, but is a planet's atmospheric pressure reliably proportional to its mass?

Venus is 90 bar, Mars is 6 mbar. Maybe not from N=3 in our solar system.

I feel you on Star Trek. It always kills me that 90% of species in the quadrant is a bipedal humanoid, although they did address this in "The Chase" (TNG:S6E20). But I digress.

Re: Four Earth-sized planets detected orbiting the nearest sun-like star

#68

Post by ashark »

alistproducer2 wrote: post #58
baron816 wrote: post #37

Ok, let's assume we find a warm, watery planet like Earth's within ~20 light years, and we figure out a way to travel >= 50% the speed of light, making it somewhat reasonable to get there. If the planet's gravity is greater than 10% different from Earth's, or its Day/Night cycle is much different from Earth's, wouldn't it still be a nightmare to live on. Anatomically modern humans have lived on Earth for 200,000 year…

I'm going to show my nerd colors here but having a thought like this has almost ruined Star Trek for me. For me I often think about atmospheric pressure. There's no way that beings from so many different planets could exist on a single star ship set at 1 Earth atmosphere. Maybe someone knowledgeable in this space can tell me, but is a planet's atmospheric pressure reliably proportional to its mass?

> Maybe someone knowledgeable in this space can tell me, but is a planet's atmospheric pressure reliably proportional to its mass?

No. Proof: Venus/Earth.

Re: Four Earth-sized planets detected orbiting the nearest sun-like star

#69

Post by fuhrysteve »

baron816 wrote: post #37

Ok, let's assume we find a warm, watery planet like Earth's within ~20 light years, and we figure out a way to travel >= 50% the speed of light, making it somewhat reasonable to get there. If the planet's gravity is greater than 10% different from Earth's, or its Day/Night cycle is much different from Earth's, wouldn't it still be a nightmare to live on. Anatomically modern humans have lived on Earth for 200,000 year…

Gene manipulation maybe? Won't work very well I suppose for existing humans, but i imagine we could eventually learn to modify genes in embryos to make them more adaptable to different environments

Re: Four Earth-sized planets detected orbiting the nearest sun-like star

#70

Post by jessriedel »

1812Overture wrote: post #30
lmm wrote: post #18

Earlier quoted context omitted.

If we wanted it badly enough, we could get to tau Ceti with current technology. The Orion designs are sound, and could carry a population capable of sustaining itself for the 100-odd years it would take to get there.

Orion designs really only work if you're evacuating the planet. Massive fallout and radiation would be caused by each launch.

The radiation is modest in the sense that the statistical value of deaths induced by higher cancer rates is much less than the cost of the launch. It is nothing like "massive fallout".
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