It could just be that they’re just so far that we’re looking at these planets millions/billion of years in the past, meaning there may may be life there but we can’t see it yet.
Earth looked pretty icy when it was “snowball Earth” and early Earth’s surface was full of molten rocks.
The Milky Way galaxy is “only” 100.000 light years across, so any planets we see around stars in our galaxy we would only see about at most 100.000 years in the past. So it would be very unlikely there would be detectable life now, where there wasn’t 100.000 years ago. And even if there were, it wouldn’t be complex life.
The most distant exoplanet we’ve found to date is 27.710 light years away, so we see that planet as it was 27.710 years ago. We’ve had humans running round for at least a 100.000 year on Earth, so if there are any aliens on that planet we would see them.
Almost forgot the mandatory XKCD reference: xkcd.com/1342/
Yeah I didn’t know we were mostly looking at planets in the Milky Way, but it makes sense. Rocky planets are very tiny compared to other stuff in the universe so it’s gotta be hard detecting them millions of light years out.
It’s worth mentioning that we can’t “see” any exoplanets at all. We know they are there by the gravitational lensing that occurs when a planet passes in front of the star it orbits. Once we calculate the position and orbit, we can track the planets and listen for any radio waves or radiation that would indicate life. We are also getting better as guessing the chemical composition of the planets, but it’s not like we can scan the surface for plants and animals.
That’s one way of detecting exoplanets, but not the most common one.
There are a couple of ways we can detect exoplanets:
We can see a wobble in the position of the star, as the star and the planet orbit around their common center of mass, which is offset from the center of mass of the star due to the mass of the planet.
Another way is to observe the light from a star, as the planet passes in front of the star some of the light gets blocked by the planet. By measuring the time and amount of light blocked, we can tell a lot about what is doing the blocking. The benefit of this method is some light passes through the atmosphere of the planet (if it has a significant atmosphere), by analyzing the spectrum we can tell what the atmosphere is made from.
We can also literally see a planet by direct observation, by blocking out the light of the central star, we can see light bouncing off the planet and observe that directly. This is hard, but has been done with several exoplanets.
Remember Venus is a Earth like planet and even relatively close to the habitable zone (depending on your definitions and error bars). Just because it’s a planet like Earth, doesn’t mean it would support life.
I wouldn’t be particularly surprised to find out Venus has life. Complex life, probably not, but something like the life we have around undersea volcanic vents seems more than possible.
I really don’t see how. Yes there is life at undersea volcanic vents on Earth, but they don’t live like in the vent itself. It’s where the temperature gets lower there is life.
As far as I know nothing can survive boiling temperatures for long and Venus has been way above boiling for millions of years. There are extremophiles that survive a little above boiling, but 400+ degrees I really don’t see how.
There is a chance in the atmosphere where there are parts with reasonable temperatures and pressures. But there is also a lot of acids floating around, which is sorta incompatible with life. If some photosynthetic life was present in the atmosphere, floating around and living on sunlight, we would have seen it by now. There would be seasonal blooms, similar to plankton in the oceans on Earth.
It’s cool to think about and I remember reading old sci-fi with Venus as a forest planet, since it’s so like Earth in a lot of ways. But in reality it’s dead dead.
Same for Mars I feel like. We might find indications life once lived there, which would be a huge deal. But as far as actual current life, I think chances are slim to none.
The mean surface temperature of Venus is only 464C.
But, with 93x the atmospheric pressure of earth, water boils at around 300C.
So…what is it that makes it difficult to thrive beyond 100C? Is it strictly the temperature, or is it the properties of water at that temperature? If it’s the latter, I wouldn’t be so surprised.
Also keep in mind that photosynthesis was a genetic accident that just happened to work really, really well, and the ability to process sunlight directly into energy was what allowed microorganisms to move away from thermal vents.
That same genetic accident could play out in a different world. Or a different genetic accident that’s more suited to their environment. Or no genetic accident at all, and life never moves past small, very secluded regions.
It’s the temperature, a lot of chemistry doesn’t work at higher temperatures because everything is too unstable. There is simply too much energy messing things up. This is why having a surface temperature that allows for liquid water to be present is such a good indicator for life. A lot of chemistry for life as we know it works at liquid water temperatures and water does play a big part as well.
The pressure would be less of an issue, there is plenty of life on Earth that thrives at huge pressures.
I’m pretty sure life on Earth evolved at the surface (or even in the atmosphere, it is thought lightning plays a part) and only adapted to use the vents later on. I’m not sure life could get started at those volcanic vents.
The pressure would be less of an issue, there is plenty of life on Earth that thrives at huge pressures.
I think their point was that the pressure “balances out” the temperature - so that enough of these chemistry does remain stable even though the temperature is high. For example - the water remains liquid because of the pressure, so that’s one requirement for life that gets fulfilled.
Countries sending people to space: … Space is a hostile environment so we have to work really hard at creating a liveable atmosphere, protect it and maintain it to ensure our long term survival.
Back in earth: The companies, corporations, governments and workers that helped to build the rocket drive away in gas powered vehicles so that they can all go live in homes powered by coal powered generators, that are pumping air borne pollution into their planet sized space craft that only has a thin layer of breathable, liveable atmosphere with no backup or emergency rescue.
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