IAC confirms existence of a Super-earth in the habitable zone of a Sun-like Star

The wiki on lagrangian points also has a bunch of useful info on this stuff. Gravity is absolutely incredible

https://en.m.wikipedia.org/wiki/Lagrange_point

There's a list of probes and telescopes that have been sent to the L1 and L2 points: https://en.wikipedia.org/wiki/List_of_objects_at_Lagrange_po... -- This includes Nasa's Genesis and Goresat, ESA's SOHO, and ISRO's Aditya.

It’s arguable that even the stuff we consider to orbit the earth like the moon is really orbiting the sun.

MinutePhysics did a great video on this: https://youtu.be/KBcxuM-qXec?si=VngVwXeRKFPjnh15

As far as I know it won't be affected at all, the project is almost fully funded from the European Space Agency. And it will most likely be launched with the European Ariane rocket.

> What's the typical time scale for a transit?

Generally measured in hours, or minutes. For example, if we were observing our system with perfect alignment, Earth's transit would be about 12 hours, Jupiter's transit around 29 hours.

> Also, why use transits instead of the Doppler method?

Quantity. PLATO can observe a sizeable portion of the sky at once, 100k+ of stars. With Doppler method the quantities are smaller + afaik there is a trade-off between number of stars being observed and the velocity we can measure. So to find Earth-like planets around Sun-like stars, we would likely have to go one or a few stars at a time.

> Has this patch of sky been selected based on previous Doppler method star studies?

I am not actively involved anymore. So I am not sure if they have already picked what part of the sky they PLATO is going to be observing. The previous Doppler method (aka as radial-velocity or rv method) star studies play a role, not only because if there's one planet, there might be more, but also because rv gave information about the star. However, keep in mind that this is to find new exoplanets, less to find out more data about existing ones. Rv will definitely be used along side PLATO, to confirm and gather more information about exoplanets that PLATO finds.

Radial velocity surveys require so damn much light, and such a complex precision spectrometer that they're only used on the very largest 8m-10m class telescopes on the ground, shooting in near infrared through the most advanced adaptive optics (or even interferometric modes) in great weather, pointed at a single target for a long period of time (this is a big deal), with a focus on super-Jupiter to Jupiter class objects in tight orbits.

The next generation of 30m class telescopes will be an order of magnitude more capable for the RV method, but even then you're not really going to be able to get fast locks on Earth analogs.

The RV method is vastly superior for detecting the planets we really care about - high confidence nearby Earth analogs. The odds of a transit being in the right plane for us to observe are tiny. But if we want to run a survey like that like it really matters (let's say a Solar system catastrophe hits a thousand years from now and humanity wants interstellar diaspora), we'll be studying the nearest thousand stars with the RV method using significant numbers of 100 meter class telescopes, or perhaps big space based interferometers produced in mass quantities, for decades.

What transit studies like Kepler do is study a small patch of crowded sky (most of the stars being very distant) with the sensitivity for very rare in-plane Earth analogs, in order to get a representative sample. When I was born we couldn't say with any confidence that planets around other stars existed, post Kepler we know that they're common. We can perform these surveys even with the shoestring budgets current governments afford astronomy because even if the odds of successfully detecting a planet that does orbit a distant star are very low, we can watch a million stars at a time.

You can find much less massive planets with the transit method.

The Doppler method relies on the planet pulling on the star to change the star's line-of-sight velocity periodically. Because planets are much less massive than stars, the star doesn't move much. You can only find massive or close-in planets with this method.

The transit method is much more sensitive to small planets like the Earth. It's true that the smaller the planet, the less of the star's light it blocks, so it's still easier to detect large planets than small planets using the transit method. However, it's much easier to detect small changes in a star's apparent brightness than it is to detect small shifts in the star's velocity.

There are a few different viable methods of detecting planets. Each has its strengths and weaknesses, and astronomers use all of them.

A different stab at this is to ask what it would take to build a telescope that could image some of these Earth-like planets, a project that turns out to be easier (in a very loose sense of that word) than sending cameras there.

The idea is you send a camera very, very far out in the Solar System (hundreds of AU) and then use the Sun's gravity well as your lens. Neat stuff and, unlike the interstellar probes, potentially doable in our lifetime.

https://en.wikipedia.org/wiki/Solar_gravitational_lens

Self replicating automata as described by Von Neumann able to repair and duplicate themselves, and other things like electronic components. ICs keep getting faster (so far) but use smaller and smaller features of silicon and could wear out from metal migration and all components will be under much more cosmic radiation than on earth. This makes a large shield of heavy material on front of vehicle to minimize this effect but that increases the energy/fuel needed. The space shuttle only took maybe week long trips but it had four computers for flight control , three extra in case of failure in different parts of the shuttle along with IIRC a separate backup backup computer in for use as last resort.

* Research faster interstellar travel, especially using something like a Buzzard engine to utilize interstellar hydrogen as resection mass. Required nuclear fusion power plants / engines and ridiculously strong magnetic fields; both seem attainable.

* Slow down human body metabolism and allow humans to stay asleep at near-freezing temperatures for a long time. If bears and chipmunks can do it, chances are humans could learn it, too.

* Invent sets of machines that can reliably self-replicate, given most basic inputs like minerals, water, and sunlight. Advanced semiconductors are going to be the tricky part.

* Study psychology, sociology, history, game theory, etc, so that the early society that will form on the new planet, isolated from Earth, would avoid at least some of the pitfalls that plagued human history on its home planet.

Time dilation means that the closer you get to the speed of light the less time you experience passing. So even a 12000 year long journey as seen from earth, if moving fast enough, could feel to the travelers like a much shorter amount of time.

Can't pulse nuclear get there? Or does it require antimatter catalyzed fission?

  > Why is it pointing at the same spot for a year?

The second dip, if roughly identical to the first dip in parameters, gives us the orbital period of the star. So now we wait a second period in order to observe the expected... Third dip, which confirms the planet if it occurs with the same parameters at the expected time.

Though I think that such observations would require at least two years, and up to possibly four years, for stars with orbits of periods similar to our own. I don't believe that a single year is long enough.

Great questions.

> Is it to get a more exhaustive survey single star or can full of stars?

PLATO will look at 100k+ stars at once. And for most we will be unlucky to see a transit between PLATO and the star. Geometrically it won't align - imagine the star systems being in different angles from us. To bring an analogue - Take a pack of cards and throw them in the air, and take a quick picture while they are sitll in the air - how many cards will be facing the camera exactly with their edge. For us to spot a transit, the planet has to pass between us and the star. If the orbital plane is not parallel to us, we will miss the transit. So that's one of the reasons why it helps to look at bunch of stars with transit method. We expect that about 1% of the orbital planes will be aligned so that we can get meaningful data.

> Or does that help it find smaller/further/different planets?

Imagine you are trying to find Earth from another solar system. The longer you look at our Sun the higher the likelihood that Earth will pass between you and the Sun. And once you get lucky, and the Earth transits between you and the Sun, the brightness of the Sun only dips about 0.01%, so that means that in order to find small planets we have to have sensitive instruments and little noise, so that the dip in brightness can be measured. Furthermore, as the planet passes the transit and continues on its orbit, the perceived brightness of the star will increase, due to the planet reflecting some extra light. Measuring that can gives us some rudimentary information about the atmosphere - e.g. if a small planet reflects a lot of light back, maybe it's covered in clouds or snow.

> And how do they pick where to point at?

There's a whole complicated process to find consensus on where to point. Basically they look at spots that have lots of stars, and they look what type of stars they are. Here the objective is to find planets around Sun-like stars, so they would prioritize fields that have more Sun-like stars.

> Is there a way of guessing the likelihood of finding a planet?

It seems that some stars are more likely to have planets than others.

Light collection. You want to observe one point for a really long time so you get a really good understanding of where the light is coming from, the properties of that light, and its behavioural patterns.

A lot of the detection is statistics around signals, so the better (read more thorough and coherent) your data (observations of changes in light), the more confidence you can have in your conclusions around what's causing the changes (planets with different atmospheres, different positions, different sizes and compositions etc...).

Sorry, I see this was answered in a previous comment: https://news.ycombinator.com/item?id=42855433

Figuring out the optimal placement of CCDs on Plato's 24(+2) cameras. Due to the way CCDs are fabricated, their properties vary a bit, they are not identical. For example, they can vary how much light they can hold before they become saturated. Given the high cost of fabricating these CCDs, and the fact that for each camera 4 CCDs are used, and all these 4 have to share front-end electronics, it was prudent to optimize their grouping to we maximise the dynamic range we get. More dynamic range means that we can tell more about the planets we find with higher confidence.

Accelerating consistently at 1G (and then -1G for the second half), should take 6 years of proper time (from the perspective of the traveller) to get there.

I don't think we'll be sending humans on these kinds of missions. We'll be sending AI systems (ship, bots, etc.) and then waiting millennia for them to report back.

You just need to be constantly accelerating to hit very high speeds very quickly. You don’t need to pull 9Gs throughout.

I have a feeling that when we figure this out, the forces of acceleration and deceleration will no longer be a problem.

Or alternatively, we make Alcubierre spacecraft work, or we move our whole planet system.

All entirely plausible approaches :D

You can’t develop tech to move intoto a computer. Although it’s a good book idea.

A kool-aid style cult where they convince their followers they will be “uploaded” once they hand over all their possessions. Then they just get shot in the head.

AI might do it, but I wouldn’t count that as us going there.

A universe full of p-zombies

It's murky concept though, so I wouldn't bet on mind uploading in our lifetime.

Some fairly fundamental things need to be answered first. Things like how does consciousness and the sense of self arise.

Naively, if you think that you are just a program that runs on a bunch of neurons in your brains, and that this program can be uploaded to a computer, you are still left with a very annoying problem: you upload a copy, and leave the original running in your squishy brain. So what then? Do you kill the original? But that involves killing a living and breathing human being. Do you wait until it dies naturally? That's still not a good answer, because you have to die so that a copy of you can continue existing.

So until we figure how to actually "teleport" our consciousness to some other host, we are in a pickle. And there's absolutely no evidence that we'll ever be able to do this teleportation. What if we never figure out the physics to do this?

Edit: I suppose you could sidestep this by generating fully digital consciousnesses that mimic what a human brain does. So a fully digital human. Assuming we can brute-force simulate a real human brain, this should be at least physically possible (as opposed to teleportation), but this still raises philosophical questions. What you are generating then aren't human beings, but conscious AI. You could argue that the human race would eventually be supplanted by immortal AI that are no longer bound by biology, but I'd argue that this isn't an evolution of the human race, rather a completely new life form (if you can call it that), which has nothing to do with humans except that we created it.

Because they want to. We see mountain, we climb it. Space is no different.

Humans generally do things out of their own self interest (which for a lot of people includes improving the living conditions of their descendants). So, if humans aren’t going to colonize space, we’ll either need somebody who… just sort of likes colonizing space with robots? Like as a hobby I guess?

Or maybe we’ll have robots at some point capable of working in their own self-interest.

If these robots find a good target and make it habitable, then you would still need to send humans at some point, right? But then you sort of wasted all these thousands of years by doing robots first, you might as well send humans too.

This general idea is explored in many other pieces of science fiction literature, but it has also recently been visualized in https://en.wikipedia.org/wiki/3_Body_Problem_(TV_series)

So kind of like living in Minnesota?

How do they evolve when they are frozen part the year before evolution?

> It's not in our habitable zone.

The habitable zone is defined as the area around a star where liquid water could be found, there is no "our" habitable zone and "their" habitable zone.

The terminology was probably chosen specifically to be somewhat clickbait, so it's probably not worth picking apart the words "habitable zone".

The core idea really boils (heh) down to water, _i.e._ the "universal solvent". You can certainly argue that liquid water may not be necessary for life, but it's hard to argue that water's presence isn't a decent prior for potential life.

But directly detecting liquid water in extrasolar planets is _hard_. So we do the next best thing and try to use whatever indirect signals we got. We know that liquid water can only exist within some range of temperatures and pressures. So let's just start with temperature.

What things can affect the surface temperature of a planet? Amount of energy received from the parent star (i.e. stellar irradiance), geothermal heating, tidal forces between a moon and planet, and probably many others. Stellar energy stands out as being the biggest contributor of energy and, fortunately, the easiest one to measure.

Of course, you could have localized sources of favorable conditions, like thermal vents or whatever, but those kinds of things are _way_ beyond our ability to detect with current tech.

So, we've narrowed down our focus to _one big contributing factor for potential life_, the amount of energy received from a planet's host star. But how can we relate energy to temperature? This is effectively where all the physics and astronomy come in via thermodynamics, orbital mechanics, and stellar physics.

Suffice it to say that all the effects combine to give a range of possible orbital radii and planet sizes where liquid water has a good chance of existing on the planteary surface.

This range of radii and planet sizes is the concept that matters. The name for this idea is "habitable zone", which suggests why we might care, compared to the more precise "orbital and planetary mass parameters favorable to liquid water formation at average planetary surface".

Reminds me of the planet inhabited by Arachna spider species in Vinge's A Deepness in the sky.

I see all those big gas giants in the habitable zone and always imagine the kind of civilisation that can emerge from that scenario.

Oh good, so it's not just me that happened to!

I wonder if jumping even makes sense at 6x gravity... maybe they would never have learned how to jump at all and always keep some limbs in contact with the ground.

Or if "humanoid" even makes sense. Something snake like that can spread out the pressure along a longer surface might be better. Or at least something with more than two legs.

What body shape would creatures living at six times the gravity even have? Would they be able to jump? Would they have a skeleton as we know it?

I would almost go looking at deep sea creatures that have to deal with extreme pressures on earth.

Or they would be forced to figure out technology that we would consider science-fiction, assuming it's possible. To consider our tech as the pinnacle is the wrong approach, I think.

Perhaps we've had it too easy here - moderate climate, oil as an easy fuel source, and gravity that isn't too oppressive. I wonder what technology would arise in a more difficult environment, such as this superearth.

Ironically I think you’d be more likely to go to space on such a planet. Imagine being barely able to jump, let alone fly. You would want to leave more than anything. It would be like a space race, against the universe.

I’m imagining some sort of mega cannon or railgun as a propulsion method to fling them off the planet.

Nuclear thermal rockets would also be an option.

Yeah, not having the radius/diameter of the planet mentioned really hurts understanding the effect of that mass. However, I doubt it is like Saturn where it could float in water.

Humans live on a planet called 'Super Earth' in that game