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

The orbital corrections are minimized at L2, because of the relative distance of the moon and other planets vs size. But that is what is accounted for in the corrections.

James Webb Telescope is at Sun-Earth L2.

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...).

> 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.

  > 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.

The L2 point doesn't really have size, and even its location isn't stable. It's a mathematical point, and when we say "orbit around L2" then that is not fully true either. The spacecraft are on what's called "halo orbit" - maybe imagine balancing a steel ball (like from a bearing) on a bottle that's sideways, it's probably easier to roll and balance the ball lenghtways of the bottle, than on rolling it sideways. The best analogy I could come up with. You don't want to be too close to the L2 point, as then the orbit would be very short and less stable, think of it as having a smaller bottle - probably harder to balance the steel ball on a smaller bottle than a big one.

> How far away PLATO will be from the James Webb Space Telescope? Probably on the magnitude of hundreds of thousands of kms on average. Interesting question though, hopefully they won't get too close :D

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.

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.

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.

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

* 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.

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

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

All entirely plausible approaches :D

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

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.

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.

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 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".

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.

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

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.

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

So please do not minimize what people are going through, it may not impact _you_, but many people are negatively impacted by the insurrectionist taking over the USA.

I'm sure you are talking about bacteria, not humans. Don't you ??? :-)