Our Solar System Isn't Normal • Hacker News Board

Re: Our Solar System Isn't Normal

#91

Post by ra » Tue, May 07, 2013, 11:27 PM UTC

tocomment wrote: post #74

ra wrote: post #3

Kepler has been revolutionary in discovering these 700 odd planetary systems, but we can't even begin to imagine what surprises await for when we point the James Webb Space Telescope at them. One of JWSTs mission objectives is to study the planetary systems discovered by Kepler, and the origins of life. http://en.wikipedia.org/wiki/James_Webb_Space_Telescope#Miss...

What specifically will the telescope tell us about this exo-planets? It surely can't image them directly, right?

Not quite, but JWST will be out at the L2 point, beyond the moon in essentially what amounts to an earth-matching solar orbit.

It's large aperture infrared sensors will have an unobstructed view of the universe (unlike Hubble which is in low earth orbit, and so only gets 90 minute windows of observation).

Basically, using IR spectroscopy we will be able to analyse the atmospheric composition as well as the thermal emissions of exoplanets.

Finally, JWST won't be limited to a small, fixed field of view like Kepler.

Re: Our Solar System Isn't Normal

#92

Post by mratzloff » Tue, May 07, 2013, 11:42 PM UTC

unreal37 wrote: post #16

I had no idea that: "Or maybe it got ejected — astronomers are finding emigrant planets, lonely orbs that wander the universe with no star, just drifting. Maybe one of those used to live here." There are planets not orbiting stars? I searched Google for "emigrant planets" and the npr article is the number 1 result for that. I think he invented the term. What are these called if I wanted to find more information about…

Reminds me of the setting for "Thundarr the Barbarian".

http://www.youtube.com/watch?v=LhAobPugvsk#t=3s

The year: 1994. From out of space comes a runaway planet hurtling between the Earth and the moon, unleashing cosmic destruction!

I always thought that intro was ridiculous until they discovered that runaway planets actually do exist and they are in fact hurtling through space...

Re: Our Solar System Isn't Normal

#93

Post by mrab » Wed, May 08, 2013, 2:22 AM UTC

If space is infinite, it is entirely possible that we are ridiculously close to the norm.

Re: Our Solar System Isn't Normal

#94

Post by mrab » Wed, May 08, 2013, 2:23 AM UTC

mrab wrote: post #93

If space is infinite, it is entirely possible that we are ridiculously close to the norm.

Or that there isn't a norm at all!

Re: Our Solar System Isn't Normal

#95

Post by gwern » Wed, May 08, 2013, 2:29 AM UTC

IsaacL wrote: post #77

gwern wrote: post #75

Earlier quoted context omitted.

I don't think it's a good candidate; certainly it pushes some amount of the Filter into our past, but even if only 1 in 700 solar systems is Sol-like, there are so many we'd still expect to see tons of aliens. For a single-step Filter or for solar systems to even be a majority of the filter, you need a step so unlikely that it can push the presence of interstellar life down from, like, trillions of star systems to ~1…

Thanks for the reply, and yes, that makes sense. What would you predict as the most likely other steps in the filter? Looking at our own planet, I would guess that it's a combination of a) it being simply infeasible to send large animals to distant stars (we haven't yet colonised the moon or even made a serious attempt to colonise low earth orbit, and we might not do so before we run out of cheap energy) and b) techn…

> What would you predict as the most likely other steps in the filter?

I don't know. Robin Hanson blogs a lot about it, but none of the steps seem terribly plausible although my favorite currently is big brains being feasible - in a number of ways, heads seem to be rare, big brains even rarer, and the costs of big brain almost too expensive to bear because neurons seem to be unable to get more efficient; one paper I liked on the topic was http://www.pnas.org/content/early/2012/06/19/1201895109.full... but you can find a lot of relevant material in http://www.gwern.net/Drug%20heuristics

Re: Our Solar System Isn't Normal

#96

Post by fusiongyro » Wed, May 08, 2013, 4:00 AM UTC

dandelany wrote: post #89

schiffern wrote: post #79

Earlier quoted context omitted.

You use "but" as though you're disputing some statement I made, when I intentionally avoided making any statement outside my knowledge. I said Kepler does use occlusion, and does not use wobbling. I'm not trying to single you out here. I'm just curious what one has to say on HN so as not to be corrected. Is there some "don't assume I've implicitly made a bunch of unsupported remarks" initialism that I can tack on to…

No need to get defensive, lutorm was just pointing out that the assumption made by the OP is still supported. His comment was simply a productive, interesting addition to yours, unlike this complaint.

I'm glad he brought it up. I have noticed it is getting awfully hard to say anything precisely enough to get it past the cadre of pedants.

Re: Our Solar System Isn't Normal

#97

Post by cmccabe » Wed, May 08, 2013, 5:08 AM UTC

fusiongyro wrote: post #96

dandelany wrote: post #89

Earlier quoted context omitted.

No need to get defensive, lutorm was just pointing out that the assumption made by the OP is still supported. His comment was simply a productive, interesting addition to yours, unlike this complaint.

I'm glad he brought it up. I have noticed it is getting awfully hard to say anything precisely enough to get it past the cadre of pedants.

Actually, the correct expression is "cohort of pedants."

Re: Our Solar System Isn't Normal

#98

Post by teamonkey » Wed, May 08, 2013, 8:00 AM UTC

Tuna-Fish wrote: post #60

teamonkey wrote: post #13

Earlier quoted context omitted.

Yes, and it's designed to detect Earth-sized planets as well as larger gas giants.

But detection probability is directly correlated to planet size and shortness of the local year. Eventually, Kepler and Kepler-like probes will be able to locate all earth-like planets with orbits that cross the path between the star and us. However, this technique will find the larger planets with shorter orbits first.

Yes indeed, but the point is that according to current theories Kepler should already be finding more Earth-sized planets than it has and few inner gas giants. The observable evidence does not match the predicted model.

Re: Our Solar System Isn't Normal

#99

Post by icambron » Wed, May 08, 2013, 8:01 AM UTC

yolesaber wrote: post #41

Shivetya wrote: post #28

Being a long time fan of 4x games, well of space games in general, this article makes me smile. I remember reading game forums where one subject that always arose was galaxy and system formations. So many of our concepts are strictly based on the very little observable data we have. Its great to live in a time when many assumptions are proven to be just that. Now the question that remains is, which configurations are…

A bit off-topic, but can you recommend any recent space 4x games to check out? The last one I played was Galactic Civilizations II and I enjoyed it immensely.

I liked Endless Space. Also Sins of a Solar Empire.

Re: Our Solar System Isn't Normal

#100

Post by pm » Wed, May 08, 2013, 9:00 AM UTC

Does anyone know how far away we are from being able to confirm the presence of planets as we might on a photograph? Or the obstacles we face getting to a high enough resolution?