21–30 of 49 posts
This is interesting, but I think an estimate of the number of planets with lots of liquid water on the surface would be more exciting. Liquid water is key to life as we know it, so knowing how common it is in the galaxy might give us some idea how likely we are to find extraterrestrial life.
I didn't think there was anything special about the size of the earth (and apparently I'm right). Can anybody explain why this is important, I don't think the article did a very good job of that.
Too small, and the planet won't be able to retain an atmosphere (e.g. Mars). Too large, and it'll probably retain too much.
While it's becoming more likely that a life supporting planet exists outside our solar system, we have the problem that mankind's recorded history is measured in thousands of years (and more than likely will only be measured in thousands of years) while the universe is a tale of billions of years.
I'd still say we are likely to see artificial satellites at some point, as our own would likely survive for millions of years in some capacity (even as junk), but the possibility of direct communication is probably never going to happen.
I'm curious how many Earth-sized planets have a twin planet like our moon. Without the moon we'd be tidally locked, and despite all our water we wouldn't be nearly as life-friendly.
My understanding was that planets further from the star would take more time to get tidally locked. Since we are quite far from the sun, it would take some time even without a moon.
Earlier quoted context omitted.
They're quite close to it. Mercury takes two of its own years to have one day, and Venus's year is less than two of its days.
This is generally suspected to be because of large primordial impacts, much like the one which it is proposed created our moon. I don't think there's anything intrinsic about Goldilocks zone orbiting rocky planets which would lend to tidal-locking with the star.
This is interesting, but I think an estimate of the number of planets with lots of liquid water on the surface would be more exciting. Liquid water is key to life as we know it, so knowing how common it is in the galaxy might give us some idea how likely we are to find extraterrestrial life.
There's a lot more to life than just liquid water. In fact there are a huge array of requirements including distance from the sun, right arrangement of planets, tidal systems, plate tectonics...
I'm curious how many Earth-sized planets have a twin planet like our moon. Without the moon we'd be tidally locked, and despite all our water we wouldn't be nearly as life-friendly.
Is having a large moon a requirement for not being tidally locked? My understanding was that planets further from the star would take more time to get tidally locked. Since we are quite far from the sun, it would take some time even without a moon.
It's also worth noting that six out of nine planets in this system are oriented in the same way as Earth and none of them has the same moon configuration as us. For example, Mars has pretty much the same tilt as us and its moons are pitiful.
I personally don't believe it's a requirement for life. We simply lack the empirical data needed to make any assumptions about habitability or even the basic configuration of habitable star systems. Until then, looking towards twin Earths is probably a good start to look for life but it's certainly not the only kind of environment stable enough to support it.
This is interesting, but I think an estimate of the number of planets with lots of liquid water on the surface would be more exciting. Liquid water is key to life as we know it, so knowing how common it is in the galaxy might give us some idea how likely we are to find extraterrestrial life.
There's a lot more to life than just liquid water. In fact there are a huge array of requirements including distance from the sun, right arrangement of planets, tidal systems, plate tectonics...
http://blogs.discovermagazine.com/cosmicvariance/2010/03/10/...
I very much like the idea that life might be a consequence of entropy and emerges everywhere where energy is in flux and matter poses a threshold against the arrow of time.
Fascinating. Our little rock could be "one in a billion" and we would still have 16 other civilizations to meet. Just in our galaxy.
How does civilization last after it acquires the ability to transmit and receive radio waves? Human certainly seems to be at least threatening portions of earth ecology. Suppose alien ecologies are, on average, more fragile and easily disrupted by the unintended consequences of transformation. Civilizations might exist but be a quite transient phenomena over the galaxy. It is very hard to predict, naturally but interesting to speculate.
Earlier quoted context omitted.
There's a lot more to life than just liquid water. In fact there are a huge array of requirements including distance from the sun, right arrangement of planets, tidal systems, plate tectonics...
I remember an old Chaos Manor column that talked about a book detailing what was needed, but I have not been able to find the book or remember the title.
http://www.amazon.com/Rare-Earth-Complex-Uncommon-Universe/d...