I've come to terms that Sol will probably eat us when it goes red, because we dicked around too long. I still have this fear though, that we are in the bottom 10% of solar systems that aren't visible to the average naked eye of beings everywhere. It's like a very very bad penis joke.
I've come to terms that Sol will probably eat us when it goes red, because we dicked around too long. I still have this fear though, that we are in the bottom 10% of solar systems that aren't visible to the average naked eye of beings everywhere. It's like a very very bad penis joke.
We can detect stars much fainter than the sun. Any lack of communication and discovery of intelligent life is almost certainly due only to the distances involved and the unfortunate business of Einstein being right.
0
#pipeCocky Stride, Musky odoursPope of Chili TownRegistered Userregular
I've come to terms that Sol will probably eat us when it goes red, because we dicked around too long. I still have this fear though, that we are in the bottom 10% of solar systems that aren't visible to the average naked eye of beings everywhere. It's like a very very bad penis joke.
You know that that's really really far off, right?
Like it won't happen for another 3 or 4 billion years
and any kind of life has only existed on earth for 1 billion.
So I’m not actually getting any work done so let me tell you about planets from an astro-biologists point of view.
We talked about planet formation a little bit, but let’s go into some more details. First a primer on the basic model of star formation: clouds of molecular dust gather by some outside forces until they reach a density such that particles begin to gravitationally attract each other. You’ll get a cascading effect from there and eventually gain enough mass and consequently density that you can get a fusion reaction going if you’re lucky.
This is from a model of star formation that you can see in detail here.
Now these clouds are huge, because this is space after all. Now some places will get lucky enough to form larger masses, around this primary mass. Again, with a lot of luck, you can get the right conditions that this mass condenses material ranging from rocky stuff to colder gases. Now with all that luck you need the star to steal just enough material such that this secondary mass doesn’t ignite a fusion reaction of its own. So all that happened, and your star survived into a stable reaction and is now on the main sequence? Congratulations you now have a planetary system!
Possible Planet formation happening around SAO 206462
Okay at this point I’ll admit that the biggest problem with all this astrophysics is that we don’t actually get to see any of this stuff happen. We just get snap shots, usually long after all the interesting stuff has happened. So actually a lot of this research is like CSI (not the TV show but the actual forensics work) so while these models are physically possible and explain most of what we see, there are often exceptions which really throw us for a loop, and theories of planetary formation have actually gone through a lot of changes recently. This is all due to exoplanets.
Not this, no, bad theory.
So we’ve been looking at stars for a long while right? We know the universe is pretty fucking big and we’ve identified a lot of stuff, 5,530,624 unique objects in the SIMBAD database. So how come we’re just seeing all these planets?
And this is just a tiny piece of the sky.
Well if you’ve tried looking up at the sun any time lately you’ll notice it’s pretty bright. Of course if you’re also a smart ass you’ll point out that looking at the moon or planets at night shows that they’re brighter than the stars around. And then I’d tell you to shut the fuck up. But anyways planets produce electromagnetic radiation in pretty much only one way and that’s Black body radiation. If you’re short on physics there, black bodies are bodies that simply absorb radiation and reradiate the energy based upon their effective temperature. Now lucky for us planets are much colder than stars, therefore they radiate a lot less energy than star. But while that makes for better living conditions it makes it a lot harder to see them when put next to bright ole star, nearly impossible in fact when you consider how low of a resolution we have at astronomical distances. The other major difficulty is that damn time scale, it takes time for planets to go around their star, on the scale of decades, and if you’re not looking in the right place for the right period time you’ll never notice the little buggers.
Yeah try resolving that difference, smart ass.
Oh apparently this graph isn't very clear if you actually want to know what's going on.
It's a log plot of luminance vs frequency, and in order to see the contrast you just want the luminance ratio between two sources.
Such that in the visual band, Earth is 10^-6 to 10^-10 times dimmer than the Sun.
So how do we find these guys? There are really 4 primary methods which can then be broken down into even smaller categories of searches and techniques.
The simplest way to detect a planet is to look for “abnormal” behavior from a star. This can involve looking at the brightness curves of the star and catching the planet in transit, seeing irregular timing in a pulsar, and motion of the star. Now I know you all are a smart bunch but let’s go a little deeper into these. Brightness curves are pretty self-explanatory the star will appear to be brighter or dimmer depending upon where the planet is in front of the star. Pulsar timing is the first successful method and capable of detecting the smallest planets, this method relies on our confidence in measuring the signals from pulsar stars and determining a period of motion for the pulsar. If the period discovered is non-cyclical then this can indicate a planet orbiting the star in question. The first discovery was actually accident, the two observers (Wolszczan and Frail) were merely attempting to gain an accurate reading of the period of PSR 1257+ 12, they continually retook data because their measurements weren’t making since and published several papers about possible causes before finding that the model of planetary bodies would explain their results.
That shit is just whack yo.
You can also measure the relative motion of the star to see if it appears to be part of a planetary system. That’s right, those little bitty planets can move around a big ol’ star. Even our star exhibits motion! Yep, you’ve probably always thought you could trust the sun to stay in the same place, but nope that sunuva gun is actually exhibiting orbital motion due to the planets in the solar system. But more accurately and successfully it can be measured using Astrometric interferometry. By using two telescopes to measure the same stars you can determine the relative motion of the stars. Unfortunately this is pretty difficult to do because the distance between the two telescopes have to be known exactly, and you need sensitive multi-element optical systems to be perfectly setup in order get usable data. These telescopes are so far limited to being on the ground which also reduces their potential resolution, and the reason for this is, they are seriously complicated and need to be just right and getting a system good enough into orbit is quite the challenge. While not the only method of measuring radial motion this is the method I am most familiar with.
Complicated.
Another method involves looking for the planet directly. This is pretty hard given the size and brightness differences between the objects, but in certain wavelengths actually doable. To assist in these searches most telescopes use special optics to blot out the star’s light, through direct or indirect methods. Even without the star washing out the image detecting a planet is still difficult due to the fact you’re primarily getting dim reflected light waves.
Like sticking your thumb in front of the sun.
The final primary method is gravitational lensing. Thanks to the scary hot mess that is the principles of General Relativity, a planet around star is capable of creating a lens for the background light by bending space and time. Now this method is nice because you don’t need to see the planet at all however this method requires a certain amount of serendipity because you need to not only look in the right place and time, but you need a background star in just the right place in order to detect this effect.
If this is confusing you can ask about it and watch me try to flounder my way around general relativity.
In actuality the theories and sometimes even practices of these methods are decades old, it is the enhancements in techniques and technologies which allow us to measure the results of our observations with much greater accuracies that have resulted in the sudden surge of planetary detections. As for the first detections, there are controversial detections as far back as 1979 which have not been convincingly confirmed. The earliest detection which has been confirmed is of a planet orbiting Gamma Cephei. Nearly every week new candidates of planetary systems are being discovered and these numbers will definitely increase as we get better at finding and confirming planets. However the majority of these methods are biased towards detecting larger planets which will limit our research and understanding of planetary mechanics.
Biased as all hell.
But what we have discovered so far has led to the retirement of some theories of planetary formation while solidifying other theories. What I’ve heard the most about it is refuting the previous theory of the gas giants migrating within the solar system during their formation and also having objects from outside the system come in and becoming large planetary bodies. Based upon what we’ve seen in most cases migratory cases are only due to the smaller early bodies colliding and changing orbits by force. At least for the orbits that stay within the system, one thing we’ve also discovered are Jupiter sized planets with highly eccentric orbits around their star. This means they’ll have orbits like comets, or our second moon, orbits which result in the planet ejecting all the other planetary bodies from the system. Talk about a rude bigger brother.
That’s a planet murderer right there.
Another really cool find that gives us really good information are young planets. Within the past 5 years we’ve found two really young planetary systems. The first was discovered around HL Tau, a little baby star at only 100,000 yrs, with the planet estimated at 1,600 years old. From the observations and models the disc around HL Tau is found to be unstable, both from gravitational forces and temperature gradients which allow for clumping of the pebble sized rocks detected within. A newer survey found another young (some sources claim the youngest? But not the research I found) planet around LkCa 15 which is around 2 Million years old, and the planet is approximately 5 times the mass of Jupiter and was formed with the last million years. Now, the findings of this aren’t confirmed because the properties of LkCa 15 aren’t measured as accurately as they could be, but this is the finding of a life time because it allows the study of a planet actually forming from a planetary disk which will have drastic results on the models with use for planetary formation.
Click for more on the simulation.
What a cute wittle babby.
Now what happens between the formation of these initial planetary bodies and a “stable” solar system like ours? Well first they start banging into each other and that helps more mass collect, or leads to moons possibly. Some might even experience collisions so violent they just flip that bitch around, like Venus. As you get farther away from the star you get to the point that you can start collecting gaseous volatiles like water and methane. There’s a lot a more gas in the universe than there is dust so these guys get bigger much faster and are able to have enough gravitational and rotational forces to retain their gaseous bodies. That gives you gas giants, now inside the warmer regions you get the small rocky objects forming until they get to approximately the size of the moon and then they start accreting atmospheres.
Kinda like this, but probably not in Technicolour.
Let’s say we’ve got a fairly stable system going on, our largest bodies are in stable orbits around the star and atmospheres have formed on the larger bodies, and our star is just chugging along. Until, we hit our first hang up, the T Tauri winds. You see there’s still a lot of gas and dust within this system, and our star isn’t quite as stable as we’d like. The star now undergoes massive coronal ejections due to its large magnetic fields. This strips our system of all that extra stuff out to certain radius past our planetary bodies. Unfortunately these strong winds also strip away the atmospheres of our planets if they’re not bond strongly enough, like the gas giants, or magnetically shielded, like we are, Yay!
This is madness.
But that’s not all! While we’ve gotten rid of all the smallest trash from our nebula, there’s still secondary bodies whose orbitals have destabilized and are now wrecking up our other planets in what we like to call the Late Bombardment. We have almost direct evidence of this period due to the craters on the Moon, Mercury, and Mars. Not only did these objects crash into the larger bodies but some were captured and turned into moons. This period lasted for a very long time and it’s possible the Moon was created when one of these bodies slammed into the Earth and there was a cataclysmic separation. We’re able to see this evidence because of the low tectonic activity on these bodies which kept these features visible as opposed to the massive rearrangements that have occurred on the Earth.
Caloris Basin – Mercury, aka one big crater.
Speaking of tectonics, what does it take to have life as we know it form on a planet? Well first you’ve gotta be in the habitable zone. Now all you smarty pants have probably heard of the habitable zone and know it’s the area around the sun which gives the possible conditions for having a correct proportion of radiation to heat the planet and not kill everything on the surface. But did you know that there is also a habitable zone in respect to the location within the galaxy? That’s right you’ve got be in the neighborhood because of rampant supernovae, too close neighbors, and the age of the region which is related what metals will be available for formation.
The previous image mentioned is retarded. Trust me.
Then perhaps you think it just has to do with getting luckily close enough to your star and being the right size. But oh it’s so much more than that, you need the right kind of core being just active enough that the planet is heated by it, and it creates a magnetic dynamo in order to protect the planet from electromagnetic radiation and the solar winds. An atmosphere will help protect from radiation as well, keep the planet warm and hold in precious resources. So while the habitable zone is primarily decided by the relative distance to the star the broadness of this zone can expand and contract depending on the properties of the planet. Heck you can even have the right conditions around a gas giant.
Seee?
The next most helpful property Earth possesses in regards to life is our atmosphere. Not just any atmosphere though, the layering and composition of our atmosphere results in a temperature gradient as you travel in altitude. By converting varying forms of radiation into the infrared spectrum the greenhouse effect not only warms the surface but it also removes X-ray and the lower bandwidth UV which can be very destructive to life on the molecular level.
it’d be sooo cold.
But what’s so important about the core and plate tectonics? Well firstly you need the core acting as magnetic dynamo to generate a strong magnetic field to protect the planet from strong solar winds. With active tectonics the planet is going to be able to better recover from outside collisions, in fact life probably just .1 Giga years after the Late Bombardment, which if you know your geology and can imagine how violent the impacts were is quite the achievement. Tectonics also provide a means of distributing resources and life in a suitable fashion. But most importantly the heat from core expands the habitable zone on the planet itself, with an active core and an atmosphere you can have two overlapping bands of heat being supplied. This heat will increase the proliferation of a life, and possibly even was required in the early period of the sun when it was much less brighter. Heck one of the theories of life on Mars is that since there’s no atmosphere its possible life formed deep below the surface where the core’s heat is sufficient. As you read this (literally, no hyperbole), missions to explore this possible theory are being proposed and considered at NASA.
Alright you’ve got a nice stable system, a planet right in the habitable zone, and soon enough you’ve got some molecular life forms on the surface of that planet. Well how in the fuck do you see that life from light years away? What’s easiest to look for is the conditions of life, I mean sure the planet may be in the right place and look to be the right age and everything, but you need more than that to suppose life. So first we can look at a temperature curve of the planet, if it has a suitable atmosphere with water vapor and everything the curve will be vastly different from a “lifeless” rocky planet. From these curves we can determine if certain elements are present as well which depending on the biologist you ask can also be a marker for life.
Quite the difference as you can see.
And that ends today’s lessons. Please excuse any of my bad grammar or typos. Also I got tired of formatting so it is what it is, deal wit it. Most of these pictures are shamelessly stolen from the papers they were initially published in, others are from textbooks or wikipedia
Kadith on
+2
WeaverWho are you?What do you want?Registered Userregular
Kadith I am going to have your children.
0
WeaverWho are you?What do you want?Registered Userregular
AnosognosWho wants to playvideo games?Registered Userregular
edited February 2012
Solid post, sir. I didn't know about T Tauri winds (thought it makes sense) or the fact that gravitational lensing can resolve planets. The method is pretty ingenious.
The crazy part is all that's just the (known/believed) requirements for microbial life. To be fair, finding extraterrestrial life at all would be a huge discovery.
But the shit that had to go down here just to temper the atmosphere enough for complex life to even have a chance to exist is pretty crazy. We're not just isolated in space, but most likely in time (though they're obviously linked, you know what I mean). The answer to the Fermi paradox seems pretty obvious: it's not a paradox.
In this image taken on Jan. 25, 2012, the Aurora Borealis steals the scene in this nighttime photograph shot from the International Space Station as the orbital outpost flew over the Midwest.
Posts
depressing.
turtles
An ancient and long derelict Prothean military base.
We can detect stars much fainter than the sun. Any lack of communication and discovery of intelligent life is almost certainly due only to the distances involved and the unfortunate business of Einstein being right.
You know that that's really really far off, right?
Like it won't happen for another 3 or 4 billion years
and any kind of life has only existed on earth for 1 billion.
Humans will be long gone.
Need some stuff designed or printed? I can help with that.
so yeah we'll have shuffled off long before anything major happens re: the sun
United States Air Force, for one.
bruce willis
:^:
ok now tell me if this is a good purchase for 20 bucks
or just lame and tacky
if so i'd want it higher resolution for $20
but still aaaaa
this thread has the Dubh stamp of approval
Twitch (I stream most days of the week)
Twitter (mean leftist discourse)
yeah i was guessing the photo wasn't doing it good justice.
it looks pretty small and not too obnoxious of a colour
so i say if you have $20 for a necklace you could definitely do worse
Because I am writing one, and it is turning out pretty long and I'm not sure I want to finish it if no one is interested.
I will of course try to include a shit ton of pictures.
@Kadith Do it.
This is the best thing I've seen all night.
I'd say space is pretty cool, yeah.
We talked about planet formation a little bit, but let’s go into some more details. First a primer on the basic model of star formation: clouds of molecular dust gather by some outside forces until they reach a density such that particles begin to gravitationally attract each other. You’ll get a cascading effect from there and eventually gain enough mass and consequently density that you can get a fusion reaction going if you’re lucky.
This is from a model of star formation that you can see in detail here.
Now these clouds are huge, because this is space after all. Now some places will get lucky enough to form larger masses, around this primary mass. Again, with a lot of luck, you can get the right conditions that this mass condenses material ranging from rocky stuff to colder gases. Now with all that luck you need the star to steal just enough material such that this secondary mass doesn’t ignite a fusion reaction of its own. So all that happened, and your star survived into a stable reaction and is now on the main sequence? Congratulations you now have a planetary system!
Possible Planet formation happening around SAO 206462
Okay at this point I’ll admit that the biggest problem with all this astrophysics is that we don’t actually get to see any of this stuff happen. We just get snap shots, usually long after all the interesting stuff has happened. So actually a lot of this research is like CSI (not the TV show but the actual forensics work) so while these models are physically possible and explain most of what we see, there are often exceptions which really throw us for a loop, and theories of planetary formation have actually gone through a lot of changes recently. This is all due to exoplanets.
Not this, no, bad theory.
So we’ve been looking at stars for a long while right? We know the universe is pretty fucking big and we’ve identified a lot of stuff, 5,530,624 unique objects in the SIMBAD database. So how come we’re just seeing all these planets?
And this is just a tiny piece of the sky.
Well if you’ve tried looking up at the sun any time lately you’ll notice it’s pretty bright. Of course if you’re also a smart ass you’ll point out that looking at the moon or planets at night shows that they’re brighter than the stars around. And then I’d tell you to shut the fuck up. But anyways planets produce electromagnetic radiation in pretty much only one way and that’s Black body radiation. If you’re short on physics there, black bodies are bodies that simply absorb radiation and reradiate the energy based upon their effective temperature. Now lucky for us planets are much colder than stars, therefore they radiate a lot less energy than star. But while that makes for better living conditions it makes it a lot harder to see them when put next to bright ole star, nearly impossible in fact when you consider how low of a resolution we have at astronomical distances. The other major difficulty is that damn time scale, it takes time for planets to go around their star, on the scale of decades, and if you’re not looking in the right place for the right period time you’ll never notice the little buggers.
Yeah try resolving that difference, smart ass.
Oh apparently this graph isn't very clear if you actually want to know what's going on.
It's a log plot of luminance vs frequency, and in order to see the contrast you just want the luminance ratio between two sources.
Such that in the visual band, Earth is 10^-6 to 10^-10 times dimmer than the Sun.
So how do we find these guys? There are really 4 primary methods which can then be broken down into even smaller categories of searches and techniques.
The simplest way to detect a planet is to look for “abnormal” behavior from a star. This can involve looking at the brightness curves of the star and catching the planet in transit, seeing irregular timing in a pulsar, and motion of the star. Now I know you all are a smart bunch but let’s go a little deeper into these. Brightness curves are pretty self-explanatory the star will appear to be brighter or dimmer depending upon where the planet is in front of the star. Pulsar timing is the first successful method and capable of detecting the smallest planets, this method relies on our confidence in measuring the signals from pulsar stars and determining a period of motion for the pulsar. If the period discovered is non-cyclical then this can indicate a planet orbiting the star in question. The first discovery was actually accident, the two observers (Wolszczan and Frail) were merely attempting to gain an accurate reading of the period of PSR 1257+ 12, they continually retook data because their measurements weren’t making since and published several papers about possible causes before finding that the model of planetary bodies would explain their results.
That shit is just whack yo.
You can also measure the relative motion of the star to see if it appears to be part of a planetary system. That’s right, those little bitty planets can move around a big ol’ star. Even our star exhibits motion! Yep, you’ve probably always thought you could trust the sun to stay in the same place, but nope that sunuva gun is actually exhibiting orbital motion due to the planets in the solar system. But more accurately and successfully it can be measured using Astrometric interferometry. By using two telescopes to measure the same stars you can determine the relative motion of the stars. Unfortunately this is pretty difficult to do because the distance between the two telescopes have to be known exactly, and you need sensitive multi-element optical systems to be perfectly setup in order get usable data. These telescopes are so far limited to being on the ground which also reduces their potential resolution, and the reason for this is, they are seriously complicated and need to be just right and getting a system good enough into orbit is quite the challenge. While not the only method of measuring radial motion this is the method I am most familiar with.
Complicated.
Another method involves looking for the planet directly. This is pretty hard given the size and brightness differences between the objects, but in certain wavelengths actually doable. To assist in these searches most telescopes use special optics to blot out the star’s light, through direct or indirect methods. Even without the star washing out the image detecting a planet is still difficult due to the fact you’re primarily getting dim reflected light waves.
Like sticking your thumb in front of the sun.
The final primary method is gravitational lensing. Thanks to the scary hot mess that is the principles of General Relativity, a planet around star is capable of creating a lens for the background light by bending space and time. Now this method is nice because you don’t need to see the planet at all however this method requires a certain amount of serendipity because you need to not only look in the right place and time, but you need a background star in just the right place in order to detect this effect.
If this is confusing you can ask about it and watch me try to flounder my way around general relativity.
In actuality the theories and sometimes even practices of these methods are decades old, it is the enhancements in techniques and technologies which allow us to measure the results of our observations with much greater accuracies that have resulted in the sudden surge of planetary detections. As for the first detections, there are controversial detections as far back as 1979 which have not been convincingly confirmed. The earliest detection which has been confirmed is of a planet orbiting Gamma Cephei. Nearly every week new candidates of planetary systems are being discovered and these numbers will definitely increase as we get better at finding and confirming planets. However the majority of these methods are biased towards detecting larger planets which will limit our research and understanding of planetary mechanics.
Biased as all hell.
But what we have discovered so far has led to the retirement of some theories of planetary formation while solidifying other theories. What I’ve heard the most about it is refuting the previous theory of the gas giants migrating within the solar system during their formation and also having objects from outside the system come in and becoming large planetary bodies. Based upon what we’ve seen in most cases migratory cases are only due to the smaller early bodies colliding and changing orbits by force. At least for the orbits that stay within the system, one thing we’ve also discovered are Jupiter sized planets with highly eccentric orbits around their star. This means they’ll have orbits like comets, or our second moon, orbits which result in the planet ejecting all the other planetary bodies from the system. Talk about a rude bigger brother.
That’s a planet murderer right there.
Another really cool find that gives us really good information are young planets. Within the past 5 years we’ve found two really young planetary systems. The first was discovered around HL Tau, a little baby star at only 100,000 yrs, with the planet estimated at 1,600 years old. From the observations and models the disc around HL Tau is found to be unstable, both from gravitational forces and temperature gradients which allow for clumping of the pebble sized rocks detected within. A newer survey found another young (some sources claim the youngest? But not the research I found) planet around LkCa 15 which is around 2 Million years old, and the planet is approximately 5 times the mass of Jupiter and was formed with the last million years. Now, the findings of this aren’t confirmed because the properties of LkCa 15 aren’t measured as accurately as they could be, but this is the finding of a life time because it allows the study of a planet actually forming from a planetary disk which will have drastic results on the models with use for planetary formation.
Click for more on the simulation.
What a cute wittle babby.
Now what happens between the formation of these initial planetary bodies and a “stable” solar system like ours? Well first they start banging into each other and that helps more mass collect, or leads to moons possibly. Some might even experience collisions so violent they just flip that bitch around, like Venus. As you get farther away from the star you get to the point that you can start collecting gaseous volatiles like water and methane. There’s a lot a more gas in the universe than there is dust so these guys get bigger much faster and are able to have enough gravitational and rotational forces to retain their gaseous bodies. That gives you gas giants, now inside the warmer regions you get the small rocky objects forming until they get to approximately the size of the moon and then they start accreting atmospheres.
Kinda like this, but probably not in Technicolour.
Let’s say we’ve got a fairly stable system going on, our largest bodies are in stable orbits around the star and atmospheres have formed on the larger bodies, and our star is just chugging along. Until, we hit our first hang up, the T Tauri winds. You see there’s still a lot of gas and dust within this system, and our star isn’t quite as stable as we’d like. The star now undergoes massive coronal ejections due to its large magnetic fields. This strips our system of all that extra stuff out to certain radius past our planetary bodies. Unfortunately these strong winds also strip away the atmospheres of our planets if they’re not bond strongly enough, like the gas giants, or magnetically shielded, like we are, Yay!
This is madness.
But that’s not all! While we’ve gotten rid of all the smallest trash from our nebula, there’s still secondary bodies whose orbitals have destabilized and are now wrecking up our other planets in what we like to call the Late Bombardment. We have almost direct evidence of this period due to the craters on the Moon, Mercury, and Mars. Not only did these objects crash into the larger bodies but some were captured and turned into moons. This period lasted for a very long time and it’s possible the Moon was created when one of these bodies slammed into the Earth and there was a cataclysmic separation. We’re able to see this evidence because of the low tectonic activity on these bodies which kept these features visible as opposed to the massive rearrangements that have occurred on the Earth.
Caloris Basin – Mercury, aka one big crater.
Speaking of tectonics, what does it take to have life as we know it form on a planet? Well first you’ve gotta be in the habitable zone. Now all you smarty pants have probably heard of the habitable zone and know it’s the area around the sun which gives the possible conditions for having a correct proportion of radiation to heat the planet and not kill everything on the surface. But did you know that there is also a habitable zone in respect to the location within the galaxy? That’s right you’ve got be in the neighborhood because of rampant supernovae, too close neighbors, and the age of the region which is related what metals will be available for formation.
The previous image mentioned is retarded. Trust me.
Then perhaps you think it just has to do with getting luckily close enough to your star and being the right size. But oh it’s so much more than that, you need the right kind of core being just active enough that the planet is heated by it, and it creates a magnetic dynamo in order to protect the planet from electromagnetic radiation and the solar winds. An atmosphere will help protect from radiation as well, keep the planet warm and hold in precious resources. So while the habitable zone is primarily decided by the relative distance to the star the broadness of this zone can expand and contract depending on the properties of the planet. Heck you can even have the right conditions around a gas giant.
Seee?
The next most helpful property Earth possesses in regards to life is our atmosphere. Not just any atmosphere though, the layering and composition of our atmosphere results in a temperature gradient as you travel in altitude. By converting varying forms of radiation into the infrared spectrum the greenhouse effect not only warms the surface but it also removes X-ray and the lower bandwidth UV which can be very destructive to life on the molecular level.
it’d be sooo cold.
But what’s so important about the core and plate tectonics? Well firstly you need the core acting as magnetic dynamo to generate a strong magnetic field to protect the planet from strong solar winds. With active tectonics the planet is going to be able to better recover from outside collisions, in fact life probably just .1 Giga years after the Late Bombardment, which if you know your geology and can imagine how violent the impacts were is quite the achievement. Tectonics also provide a means of distributing resources and life in a suitable fashion. But most importantly the heat from core expands the habitable zone on the planet itself, with an active core and an atmosphere you can have two overlapping bands of heat being supplied. This heat will increase the proliferation of a life, and possibly even was required in the early period of the sun when it was much less brighter. Heck one of the theories of life on Mars is that since there’s no atmosphere its possible life formed deep below the surface where the core’s heat is sufficient. As you read this (literally, no hyperbole), missions to explore this possible theory are being proposed and considered at NASA.
Alright you’ve got a nice stable system, a planet right in the habitable zone, and soon enough you’ve got some molecular life forms on the surface of that planet. Well how in the fuck do you see that life from light years away? What’s easiest to look for is the conditions of life, I mean sure the planet may be in the right place and look to be the right age and everything, but you need more than that to suppose life. So first we can look at a temperature curve of the planet, if it has a suitable atmosphere with water vapor and everything the curve will be vastly different from a “lifeless” rocky planet. From these curves we can determine if certain elements are present as well which depending on the biologist you ask can also be a marker for life.
Quite the difference as you can see.
And that ends today’s lessons. Please excuse any of my bad grammar or typos. Also I got tired of formatting so it is what it is, deal wit it. Most of these pictures are shamelessly stolen from the papers they were initially published in, others are from textbooks or wikipedia
Seriously I got a huge laugh out of this. (I don't know how to work that equation)
As long as one person appreciates that post, I consider my mission accomplished.
Looking back over the figure I now realize that it's not at all clear unless you already know what you're looking at.
It's a log plot of luminance vs frequency. So to measure to the contrast you take the ratio of the two sources.
So in the visual band Earth is 10^-6 to 10^-10 times dimmer than the Sun.
That may be true, but at least i'm a drunk nerd.
You are a cool guy
And that clearly has no place in space.
*gasp*
The crazy part is all that's just the (known/believed) requirements for microbial life. To be fair, finding extraterrestrial life at all would be a huge discovery.
But the shit that had to go down here just to temper the atmosphere enough for complex life to even have a chance to exist is pretty crazy. We're not just isolated in space, but most likely in time (though they're obviously linked, you know what I mean). The answer to the Fermi paradox seems pretty obvious: it's not a paradox.
It is definitely on my bucket list to see the northern lights in person.