Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

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

nature.com

Post reply on HN
Print view View original

511–520 of 754 posts

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

#511

Post by sbierwagen »

TurplePurtle wrote: post #502
sbierwagen wrote: post #472

Earlier quoted context omitted.

EDIT: My math was totally wrong. 10 trillion dollars, 0.1x world GDP. (Still a lot of money though) Leaving the old text below so the replies make sense. --- To move 6,000,000 megatons of fuel into low earth orbit would take 111,111 Falcon Heavy launches, at a total cost of $10,000,000,000,000 dollars. (10 quadrillion dollars, 93x world GDP) Something that takes the total global economic output of the planet a centur…

I'm not sure if your error is in the number or in the words, but the number you wrote down is 10 trillion dollars.

Oops.

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

#512

Post by alnitak »

Depending on how habitable those planets are, if there was an actual entity modeling the universe for humans as some close minded ideologies tend to think, well we would be living there and not in a little blue island in the middle of desolation. Nice blow.

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

#513

Post by shawn-furyan »

DougWebb wrote: post #272
dmreedy wrote: post #70

Earlier quoted context omitted.

I guess J.J. Abrams is somewhat forgiven for this, then: http://vignette4.wikia.nocookie.net/startrek/images/2/29/Vul... [edited for direct .jpg]

I always thought that Firefly's scenario of a bunch of Earth-like worlds in close enough proximity to have regular trading ships flying between them was unrealistic. Now, not so much. This system even fits in with the "Abandon Earth en-mass, move to new set of worlds" backstory. So, what did J.J. know, and when did he know it? And for that matter, how did he know?

Corrections aside, it is an interesting observation that Firefly is less outlandish with this discovery (not a criticism, Firefly is optimized for fun, not scientific plausibility). Still, assuming light speed travel, Firefly's inhabited planets are still a heck of a lot closer, since the crew doesn't seem to noticeably age between the half dozen or so star systems that they visit, and don't appear to have any kind of tech to reversibly[1] halt their metabolisms.

[1] the reversibility it the hard part. Tech for halting metabolic processes irreversibly has been around for quite some time ;)

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

#514

Post by flukus »

tempestn wrote: post #399
blueprint wrote: post #312

Earlier quoted context omitted.

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.

What about a comet impact? That's extinction level and comes with very little warning.

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

#515

Post by flukus »

blueprint wrote: post #330
matwood wrote: post #295

Earlier quoted context omitted.

NASA is not standing still. Europa just went to the next stage for exploration. http://www.jpl.nasa.gov/news/news.php?feature=6755 It just takes a lot of time to plan and build ships for space travel.

You're completely missing my point. We've known about climate change for a long time. Since the 60s/70s, no? But nobody has been able to realize what it really is, because scientists do not understand gravity yet. I've been begging people to confirm this for themselves instead of believing what others say about it. If people really knew what global warming was they would have started working on ships decades ago. My…

> We've known about climate change for a long time. Since the 60s/70s, no? But nobody has been able to realize what it really is, because scientists do not understand gravity yet.

We know exactly what climate change is and it has nothing to do with gravity.

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

#516

Post by the_watcher »

bcaulfield wrote: post #10
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…

So, basically, this is cooler than just about any world that's been depicted in sci-fi.

Anyone else immediately think that we'd discovered Krypton when they read "red sun?"

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

#517

Post by LrnByTeach »

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…

As these planets are most probably TIDALLY LOCKED, making it hard for LIFE to thrive.

> All seven of TRAPPIST-1's planets orbit much closer than Earth orbits the Sun. A year on the closest planet passes in only 1.5 Earth days, while the sixth planet's year passes in only 12.3 days

>Tidally locked planets likely have very large differences in temperature between their permanently lit day sides and their permanently dark night sides, which could produce very strong winds circling the planets, while making the best places for life close to the mild twilight regions between the two sides.

> Another important consideration is that red dwarf stars are subject to frequent, intense flares that are likely to have stripped away the atmospheres of any planets in such close orbits.

https://en.wikipedia.org/wiki/TRAPPIST-1

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

#518

Post by flukus »

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)

Is there any reason to accelerate to the half way point? Accelerating to .99c is much faster and would use much less fuel. It also wouldn't make the travel time much different, to the outside observers anyway.

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

#519

Post by acqq »

rlanday wrote: post #430
hughes wrote: post #356

Earlier quoted context omitted.

Are you saying that they don't orbit their star because some of them gravitationally influence each other? Or are you saying that nothing outside of our solar system can be a planet? Either way, NASA should schedule another press release about taking celestial pedantry to a new level.

My understanding is that according to the IAU definition, a "planet" must orbit the sun and not any other star. Kind of reminds me of when people thought the solar system was the center of the universe.

The word planet comes from the ancient Greek word for "wanderer" which they used to refer to the wandering stars, the only stars that moved across the sky in relation the all other stars, only five of them visible, assigned to the gods and one goddess: Hermes, Aphrodite, Ares, Zeus and Cronus. Since then, the definition of the planet had to be modified as there are a lot of bodies orbiting the Sun known today. According to the latest precise definition, even Pluto isn't a planet anymore (but a dwarf planet).

In this light, I don't see the problem in making the difference between the planets (orbiting our Sun) and the exoplanets (orbiting other stars, see my other post here).

These guys however would like to remove the International Astronomical Union's definition from 2006 and to introduce the new with which even the moons(!) of the planets would be called "planets":

https://arstechnica.com/science/2017/02/how-positively-peeve...

As the reporter cleverly summarized, their definition could be simpler stated as, "round objects in space that are smaller than stars." Then there would be around 110 such "planets" around the Sun, and the exoplanets would also be, of course, just "planets."

Their reasoning:

"In the mind of the public, the word “planet” carries a significance lacking in other words used to describe planetary bodies. In the decade following the supposed “demotion” of Pluto by the International Astronomical Union (IAU) [1], many members of the public, in our experience, assume that alleged “non-planets” cease to be interesting enough to warrant scientific exploration, though the IAU did not intend this consequence [1]. To wit: a common question we receive is, “Why did you send New Horizons to Pluto if it’s not a planet anymore?” To mitigate this unfortunate perception, we propose a new definition of planet, which has historical precedence [e.g., 2,3]. In keeping with both sound scientific classification and peoples’ intuition, we propose a geophysically-based definition of “planet” that importantly emphasizes a body’s intrinsic physical properties over its extrinsic orbital properties."

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

#520

Post by gwern »

gydfi wrote: post #407
noobermin wrote: post #88

Earlier quoted context omitted.

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?

Maybe but I like to think there are creatures living in the temperate rim of a tidally locked planet somewhere debating whether life could possibly evolve on a rotating planet. "I mean, there'd be temperature fluctuations of tens of degrees every day! It would be dark half the time! How could life survive in such an unstable environment?"

And don't forget: there will be long-term cyclical trends of dozens of degrees due to geometric properties of the orbit and hypothesized tilts!
Post reply on HN