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Seven earth-sized planets discovered circling a star 39 light years from Earth

nature.com

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Re: Seven earth-sized planets discovered circling a star 39 light years from Earth

#111

Post by rflrob »

JumpCrisscross wrote: post #34
ionwake wrote: post #17

Earlier quoted context omitted.

Out of interest , although dimmer, are there any potential hazards simply due to the proximity of a dim star?

> are there...hazards simply due to the proximity of a dim star Tidal locking [1]. Similar to how our moon shines at us ass first all the time, the planets around TRAPIST-1 would be expected to have one face locked to their star. Instead of an equatorial belt bookended with loops of temperate zones, as we have on Earth, we should expect, climatically, an "equatorial" face and a "polar" face separated by a tropic-to-t…

This would be my first thought as well, but the original article says that they are near-orbitally resonant. It seems possible to me that the regularly passing nearby planets could apply enough of a torque to counteract the tidal locking---though I don't have a good sense of the order of magnitude of the forces, so maybe not.

Re: Seven earth-sized planets discovered circling a star 39 light years from Earth

#112

Post by aaronblohowiak »

jdormit wrote: post #39
e0m wrote: post #33

To get a spacecraft there it would take: Accelerating at 1g the 1st half, and decelerating at 1g the 2nd half, the traveler would experience 7.3 years of time. For observers it would take 41.8 years at a max speed of 0.998c If you had a near perfect hydrogen -> helium fusion engine, it'd take about 6 million tons of fuel (about the mass of the Pyramids of Egypt or 2,000 Saturn V rockets)

We don't have any spacecraft that can go that fast, do we?

I think we do if you look at it in terms of acceleration. As I understand it, In space there is almost 0 friction so "fast" is more about acceleration than "top speed". In this view, 1g isn't that fast.

Re: Seven earth-sized planets discovered circling a star 39 light years from Earth

#114

Post by actsasbuffoon »

e0m wrote: post #33

To get a spacecraft there it would take: Accelerating at 1g the 1st half, and decelerating at 1g the 2nd half, the traveler would experience 7.3 years of time. For observers it would take 41.8 years at a max speed of 0.998c If you had a near perfect hydrogen -> helium fusion engine, it'd take about 6 million tons of fuel (about the mass of the Pyramids of Egypt or 2,000 Saturn V rockets)

It would take 37 days at warp 6 (assuming we're using the new warp factors established in The Next Generation). I have no idea how much dilithium crystal would be required though.

Re: Seven earth-sized planets discovered circling a star 39 light years from Earth

#115

Post by cgriswald »

rm_-rf_slash wrote: post #30
ionwake wrote: post #17

Earlier quoted context omitted.

Out of interest , although dimmer, are there any potential hazards simply due to the proximity of a dim star?

Actually they are fewer. A dim star has less high energy radiation and a lower probability of harmful solar flares.

That's not quite true. These planets are very close to the star and can receive large doses of the little bit of harmful radiation that the star puts out. Additionally, these planets put out a lot of infrared, but not a lot of higher energy photons, and life-as-we-know-it needs those higher energy photons. That infrared is also absorbed by water in any atmospheres or oceans that are present, leaving even less for life. Finally, these types of stars tend to have rather variable output in their spectrums, which may make it difficult for life to adapt.

Re: Seven earth-sized planets discovered circling a star 39 light years from Earth

#116

Post by Normal_gaussian »

noobermin wrote: post #88
JumpCrisscross wrote: post #34

Earlier quoted context omitted.

> are there...hazards simply due to the proximity of a dim star Tidal locking [1]. Similar to how our moon shines at us ass first all the time, the planets around TRAPIST-1 would be expected to have one face locked to their star. Instead of an equatorial belt bookended with loops of temperate zones, as we have on Earth, we should expect, climatically, an "equatorial" face and a "polar" face separated by a tropic-to-t…

Of course, #askNasa didn't win me a question, but could any astrobiologists comment on this question: Tidal locking means the planets would always have a side facing the star, leading to very different thermodynamics in terms of climate and weather on the planet, not to mention radiation. Doesn't that very much hurt the chances for life on those planets?

I would be very interested in seeing comparative weather simulations for a fictional tidal locked planet to Earth and the other Sol planets.

Re: Seven earth-sized planets discovered circling a star 39 light years from Earth

#117

Post by kristianc »

Do we know definitively that there are no other planets in this system?

The presence of a large, Jupiter-sized planet in a system is thought to be helpful for deflecting asteroid impacts. Obviously we are talking 'to scale' given TRAPPIST-1 itself is around the size of Jupiter!

The more we learn about this system is going to be fascinating though - the supposed inward migration of these planets may even help us understand more about how our own system formed.

Re: Seven earth-sized planets discovered circling a star 39 light years from Earth

#118

Post by 6502nerdface »

r721 wrote: post #32

Wiki says "TRAPPIST-1 is an ultracool dwarf star that is approximately 8% the mass of and 11% the radius of the Sun. It has a temperature of 2550 K and is at least 500 million years old." https://en.wikipedia.org/wiki/TRAPPIST-1 Too young star for alien life hopes?

> Too young star for alien life hopes?

Not necessarily -- life on Earth may have arisen a remarkably short time after accretion, perhaps even in the first few hundred million years. See this old HN discussion: https://news.ycombinator.com/item?id=10415212

Re: Seven earth-sized planets discovered circling a star 39 light years from Earth

#119

Post by John23832 »

noobermin wrote: post #88
JumpCrisscross wrote: post #34

Earlier quoted context omitted.

> are there...hazards simply due to the proximity of a dim star Tidal locking [1]. Similar to how our moon shines at us ass first all the time, the planets around TRAPIST-1 would be expected to have one face locked to their star. Instead of an equatorial belt bookended with loops of temperate zones, as we have on Earth, we should expect, climatically, an "equatorial" face and a "polar" face separated by a tropic-to-t…

Of course, #askNasa didn't win me a question, but could any astrobiologists comment on this question: Tidal locking means the planets would always have a side facing the star, leading to very different thermodynamics in terms of climate and weather on the planet, not to mention radiation. Doesn't that very much hurt the chances for life on those planets?

I'm not an astro-biologist, but I assume that it wouldn't be conducive to life as we know it, but that doesn't rule out all life.

Re: Seven earth-sized planets discovered circling a star 39 light years from Earth

#120

Post by [deleted] »

dexwiz wrote: post #62
jdormit wrote: post #39

Earlier quoted context omitted.

We don't have any spacecraft that can go that fast, do we?

No, but we probably could with enough fuel. The bigger issue is space dust. Hitting it at relativistic speeds would be like flying into a cosmic shotgun for the entire journey.

[deleted]
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