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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

#21

Post by kibwen »

fsiefken wrote: post #8
h4l0 wrote: post #2

Hearing distances like 12 light years makes you think if it is ever possible to travel there. However, when you start to think about it, nihilist thoughts start to kick in.

With the EMdrive it'll take around 150 years (give or take a century), so it's within the realm of possibility if we can engineer a ship with shielding that can last that long. The mission becomes an order of a magnitude more difficult if you want to put a viable human population on it... watch Pandorum for one scenario.... perhaps it's best to send a seed ship (as written about in the excellent SF story by Pamela Sa…

150 years by what calculations? Are you also factoring in deceleration time?

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

#22

Post by swamp40 »

semaphoreP wrote: post #20
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.

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.

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

#23

Post by BurningFrog »

eggpy wrote: post #12
semaphoreP wrote: post #3

This title is a bit imprecise. They detected four planets with lower bound on their masses to be down to 1.7 Earth masses. Because these planets don't transit, there are no direct measurements from their radius. They can use mass-radius relations to infer the radius of these planets, but the key finding is their masses (actually lower bounds on their masses).

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.

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

#24

Post by BurningFrog »

frgtpsswrdlame wrote: post #9

Is there any benefit to the planets being earth-sized? I would think the important part is that they're in the habitable zone.

I don't think it changes the possibility for life at all.

It does make colonizing it seem less possible, but that's hardly a practical concern anytime soon.

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

#25

Post by ramidarigaz »

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.

Kepler has only focused on two tiny patches of the sky in its lifetime IIRC.

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

#26

Post by ajross »

kibwen wrote: post #21
fsiefken wrote: post #8

Earlier quoted context omitted.

With the EMdrive it'll take around 150 years (give or take a century), so it's within the realm of possibility if we can engineer a ship with shielding that can last that long. The mission becomes an order of a magnitude more difficult if you want to put a viable human population on it... watch Pandorum for one scenario.... perhaps it's best to send a seed ship (as written about in the excellent SF story by Pamela Sa…

150 years by what calculations? Are you also factoring in deceleration time?

An "EmDrive" is a pseudoscience device. Poor calculation rigor is not the biggest error component in that number.

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

#27

Post by pixl97 »

arnarbi wrote: post #6
deanCommie wrote: post #5

Key line to mitigate disappointment: "The outer two planets around tau Ceti are likely to be candidate habitable worlds, although a massive debris disc around the star probably reduces their habitability due to intensive bombardment by asteroids and comets."

We'll just wear helmets!

Today's forecast is a 50% chance of iron magma precipitation with a light sulfur fog.

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

#28

Post by hinkley »

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.

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.

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

#29

Post by gnarbarian »

lmm wrote: post #18
chrismealy wrote: post #7

The fastest spacecraft ever built would take 4000 years to travel one light year.

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.

https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propuls...

Project Orion is awesome and I am a big supporter. Unfortunately people won't stand for the thousand some odd nuclear bombs it would take to get the interplanetary version out of the atmosphere.

Because it is so massive, building it in space also poses a problem unless we capture a iron meteorite and bring it back or mine/build it on the moon. Both of which we should really do because it would be by far the fastest ship we can build right now.

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

#30

Post by 1812Overture »

lmm wrote: post #18
chrismealy wrote: post #7

The fastest spacecraft ever built would take 4000 years to travel one light year.

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.
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