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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

#391

Post by [deleted] »

dwaltrip wrote: post #82
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?

In the Q&A session they said it's difficult to constrain the age of the long-lived ultraviolet dwarf stars once they finish the active early phase, as their lifecycle progresses so slowly. They live for more than a trillion years, compared to stars like our sun which are larger and burn through their fuel in less than 10 billion years. It's somewhat counterintuitive, but the bigger a star is, the faster it uses up it…

[deleted]

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

#392

Post by acqq »

dgudkov wrote: post #354
sampo wrote: post #223

Earlier quoted context omitted.

Earth is 4.5G years old, and the earliest undisputed microbial life fossils are 3.5G years old, so that gives 1000 million years. But we can also say that Earth was cool enough for liquid water 4.4G years ago, and there are some findings suggesting microbial life already 4.1G years ago. So only 300 million years, at maximum.

Moore's Law applied to DNA complexity hints that life could be way older than Earth itself: https://www.technologyreview.com/s/513781/moores-law-and-the...

I suspect something's not right, on their graph, mammals are on the top, but this flower has 50 times bigger genome than a human:

https://en.wikipedia.org/wiki/Paris_japonica

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

#393

Post by acqq »

rlanday wrote: post #349

Now technically, according to the International Astronomical Union, these bodies can't be planets since they don't orbit the sun: https://www.iau.org/static/resolutions/Resolution_GA26-5-6.p... "1. A planet is a celestial body that (a) is in orbit around the Sun" Makes me wonder how much this definition of a planet was motivated by the desire to be able to give elementary schoolers a nice small set of things to memor…

NASA therefore uses the term "exoplanets":

https://www.nasa.gov/press-release/nasa-telescope-reveals-la...

Also:

https://en.wikipedia.org/wiki/Exoplanet

"An exoplanet or extrasolar planet is a planet that orbits a star other than the Sun. The first scientific detection of an exoplanet was in 1988."

Nature did their own clickbaiting with "alien worlds" in the title which was at least here on HN corrected with "planets" whereas the technical term would be "exoplanets."

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

#394

Post by hcarvalhoalves »

mtgx wrote: post #42
eb0la wrote: post #3

At Voyager-I speed (17km/s) we need just 688k years to get there. Not bad considering the humble satelite doesn't accelerate anymore.

I doubt we'll attempt serious inter-stellar travel before we figure out antimatter or black hole-powered engines. So we may have to wait a century or two. This century we should be more worried about making fusion-powered intra-solar system travel a common thing, and about establishing large colonies on Mars and several moons.

> So we may have to wait a century or two.

It took some thousands of years to be able to circumnavigate the planet, and some centuries after that to do it quickly and safely.

It feels IST in a matter of centuries from now is extremely optimistic.

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

#395

Post by Aardwolf »

dmix wrote: post #6

My favourite part of the press release: > The planets also are very close to each other. If a person was standing on one of the planet’s surface, they could gaze up and potentially see geological features or clouds of neighboring worlds, which would sometimes appear larger than the moon in Earth's sky. > In contrast to our sun, the TRAPPIST-1 star – classified as an ultra-cool dwarf – is so cool that liquid water cou…

And the name of the star is shared with Trappist beer!

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

#396

Post by ryen »

dmix wrote: post #6

My favourite part of the press release: > The planets also are very close to each other. If a person was standing on one of the planet’s surface, they could gaze up and potentially see geological features or clouds of neighboring worlds, which would sometimes appear larger than the moon in Earth's sky. > In contrast to our sun, the TRAPPIST-1 star – classified as an ultra-cool dwarf – is so cool that liquid water cou…

Wonder how tidal forces from these planets would affect [possible] oceans on their neighbors. Would imagine it would make for quite a perturbed environment.

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

#397

Post by stagbeetle »

logfromblammo wrote: post #182
vkou wrote: post #21

Earlier quoted context omitted.

At a constant 1g of acceleration, you could travel there, from the traveler's point of view, in ~2-3 years. (And in ~40 years from a stationary observer's point of view.) Mind you, a constant 1g acceleration (Or accelerating any human-carrying spaceship to relativistic speeds, really,) is about as plausible as a spaceship driven by pixie dust and unicorn farts.

If pixie dust is plutonium and unicorn farts are tetradeuterium-methane, you could get there in 400 years or so, Earth-time, 398 years shipboard time. So you really need your pixie dust to be antimatter, and your unicorn farts to be terawatt lasers. For now, the wait calculation suggests that anyone leaving now will reach their destination after someone who waits to leave until after the next breakthrough in space pr…

I see "antimatter" and "black hole" being thrown around as a source of propulsion in this thread.

Is this based on anything real like using the energy created from the radiation or just sci-fi speculation?

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

#398

Post by literallycancer »

blueprint wrote: post #320

> The launch cost of launching the mass of the pyramids of gaza into orbit would bankrupt the richest economies. Yeah… cause the way you're thinking about doing that is literally the only way in the world to accomplish the task. Not. It's not my job to qualify whether it HAS to be done to you. And even though I am the one presenting this information and this evidence, it is indeed your job to confirm it. Otherwise, y…

I don't think the way you are arguing your points does you any favors.

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

#399

Post by tempestn »

blueprint wrote: post #312
drzaiusapelord wrote: post #296

Earlier quoted context omitted.

If its affordable to send people to an off world colony then its affordable to bomb it when war on Earth breaks out. Fleeing isn't going to help in a wartime situation and the idea it will not be targeted by world powers is a little naive.

I said nothing about war..?

There's no other conceivable extinction event that could occur "a couple years out". If you're talking climate change, then I agree that's a major problem, but on the order of at least decades.

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

#400

Post by gydfi »

tajen wrote: post #318
longerthoughts wrote: post #136

Earlier quoted context omitted.

Regular shuttles for interplanetary travel timed with periodically favorable orbital positions?

At that distance, gravity must be really fun. Tides are not only for water, such tides can also change the height of mountains, the balance of high-rise buildings, infer on volleyball rules, make you fart because of changes in atmospheric pressure, or... be leveraged to generate electricity. Those guys have simili-infinite energy at human scale.

Would they? I mean, we can see geological features on our moon, and our tides are orders of magnitude away from being rock-tearing events. I mean, the moon is small, but... how close do these planets approach, anyway?
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