How do we discover more exoplanets? Neil deGrasse Tyson and comedian Matt Kirshen explore telescopes, exoplanets, and more with professor of astrophysics and Principal Investigator of HATNet Exoplanet Survey, Gáspár Bakos.

On the next episode of StarTalk, it's a Cosmic Queries, featuring the expertise of a colleague of mine from Princeton University.

The name is Gaspar Bakos, and he is at the Department of Astrophysics there, where he has developed a system of small telescopes to discover exoplanets.

So, we're going to find out how does that work, why does a small telescope still get to contribute to a field that's on the frontier, and we'll also learn how these satellite trails that we've read all about and seen videos of launched from rockets and how they affect the data that he's searching for, as well as the beauty and majesty of the night sky that we've all missed ever since cities have become electrified.

Welcome to StarTalk, your place in the universe where science and pop culture collide.

Neil deGrasse Tyson here, your personal astrophysicist.

And this is yet another Cosmic Queries edition.

I'm excited about this topic, not least because a couple of weeks ago, as a birthday present from my wife, I went to Mount Wilson Observatory for a lecture and then a look through the big telescope.

Yeah, so I feel like I'm up at an amateur level now on this, but I want to hear from the pros.

So there are people who are experts in all of the things I listed, 1 of whom is actually just across the river, across the moat here, we call it the Hudson River, over in New Jersey, is a colleague of mine from Princeton Department of Astrophysical Sciences, Gaspar Bakos.

And you are a PI on a project called HatNet, which is search for exoplanets.

And of course, people, I don't think everyone thinks much about the fact that at any given spot on earth where most people live you don't see the whole sky so if you're gonna find exoplanets in a place you're not looking what do you do?

Indeed there is a project called headnet which is which is an automated telescope system because finding exoplanets with a naked eye would be really very challenging, I would say impossible.

But the idea behind robotic telescopes is they can actually scan, monitor big areas of the sky non-stop and then we can use computers to analyze all the data and we can place these robotic telescopes to like fancy astronomical locations which have clear skies, high mountains, and have internet and power.

And they're not very large, so it's not a big disruption to the physical location.

This was an amazing thing that we realized about sort of 20 years ago that we can actually do cutting-edge science with tiny telescopes, because stars, when a planet goes in front of them, they blink, and that blink can be detected with a small telescope if it's all carefully engineered and run, so.

Right, but, Hattonet, apparently, it's not, you have telescopes in multiple places on Earth.

So the transits are elusive and the transit of a planet, that the time instance when it goes in front of its star, will have nothing to do whether it's daytime or nighttime on Earth from a given location.

So it might actually go in front of its star and the star blinks when it's broad daylight here in Princeton.

So the idea is to put telescopes around the globe at tactical longitudes so we can observe around the clock.

In other words, the sun never rises above our telescope empire.

That's an equivalent, this whole British empire, sun never sets.

It never rises either, but logically it also never rises.

But okay, so you can cover it, so I love your phrase, tactical longitudes, but now what about latitude?

Yeah, you can also be tactical with latitudes because here's the thing, if you go too far to the south, you freeze to death.

If you go too close to the equator, then you have too much humidity and jungles, which are lovely things, but it's just not good for astronomy.

too far south if you're in the southern hemisphere.

In the north it's the same thing, I mean, and plus, in the north if you go too far north there's no ground you can touch, that's another problem.

Most people don't know that Santa Claus lives on an ice floe, okay?

Most illustrations of Santa Claus at his workshop, they have mountains and pine trees and things.

This would be Santa Claus in a bathing suit, right?

Last year, the Arctic did not freeze over.

Ships can be crossing it at any time or something.

So where are your Southern Hemisphere telescopes?

So the first station we built is in Chile at Las Campanas Observatory in the Andes.

So it's a pre-existing observatory location, right?

So you didn't have to build roads, you didn't have to put in the internet, like you said, you just ride the pre-existing infrastructure.

But we did pour the concrete piers, we pulled in a container, like a shed for instruments, and we hold in all the things and build all the infrastructure up for our local installation.

But there is other infrastructure already there.

The second 1 is in Namibia in the Kalahari Desert.

There is an existing installation there called the HESS telescopes.

So again, we had internet, we had power, sort of, you know, it was a bit tough in the beginning, but it's an amazing place.

And the third 1 is in Australia, in Outback, at Siding Spring Observatory, which again has sort of very good infrastructure.

And last I checked, the catalog of exoplanets was nicely rising through 5, 000, and you're going to make predictions about how soon we'll hit maybe 10, 000, doubling that number?

Yeah, that's a very hard thing to extrapolate.

At what rate are you discovering exoplanets?

Yeah yeah well yeah are you good at this?

Yeah well so our rate we actually found 140 something exoplanets between 2006 and now and our rate has been going down because our space missions have been contributing majority of the discoveries.

But you know space missions have a limited lifetime so Kepler was a famous 1 that flew from 2009 through sort of

And then TESS is now a highly productive mission which we run for a limited time.

And TESS is itself an acronym, what is it?

So, I've been fascinated by this, so, but you'll continue cranking with or without the space observatories is what you're saying.

Well, an idea what we do is we complement the data coming from space.

Let's say TESS observes an area for 27 days non-stop, and it finds transiting planets.

Now some of the transits will be single transits, there will be just a blip in the light curve, we don't know what's the next blip is happening, we don't know.

And but if we complement it with ground-based data, we can solve for a period and then...

So TESS makes the discovery, now you follow up to verify that it's a repeating phenomenon.

Because if they just see 1 blip, that could have been anything.

Oh yeah, yeah, and there's many false positives.

That's the other thing that there's 5, 000 planet candidates right now, but I think the number of confirmed planets with mass is measured, say, is about 270 from tests.

So there's like a huge difference between the 2.

All right, so it's still a lot of work to happen there.

So now you're also involved in, you're a part of a documentary called Dark Sacred Night.

Well, I've been, I grew up on the dark skies as a kid.

I grew up in the northeast part of Nigeria on the border of Cameroon.

Yeah, there was no electricity and no TV, no internet, no phone, But we had the dark sky and it was really amazing.

I remember as a five-year-old looking up and I would see the Milky Way going down to the fence or whatever, the horizon, you know?

And then I realized when we moved back to Europe that this is not something I see from there.

I mean, it's just all that beauty is sort of missing for...

I felt pity for all of us here, we just don't see this thing.

And I felt, is it actually a necessity or is it a stupidity?

And after a while I realized it is more of a stupidity.

If lights were properly designed and aimed down, it was not wasted, then we would actually see the make-away from majority of the US.

So we'd have both civilization plus a dark night sky is what you're saying.

So not having our cities any less lit, but just having smarter lighting that is less wasteful, less pointing up and escaping less.

Matt, you know what I tell people when I'm in an airplane and we're about to do our final loop to the airport around a city?

I'd say to the person next to me, you see that area of streetlights down there?

And I say, someone is paying money to send photons to me in an airplane.

I mean, the estimate now is something like 50% of the light emitted in the US by light fixtures goes up straight in the sky.

And the amount of money, which just Neil referred to, is right now the estimate is about $3 billion per year is converted into photons that go up in space simply because of the cool design.

Just to light the clouds and airplanes so we can see the city.

I've talked about this before on this show, but it, because I grew up on the outskirts of London and then now I live in Los Angeles, and Neil, you were up in New York, and it's just, I remember the first time I was somewhere that was sort of remote and in the middle of nowhere, and you could really see the sky, and I was like, oh, that's what stars are.

That's what people used to write poems about and draw pictures of and stuff.

So Matt, that moment for me was in the Hayden Planetarium.

So Matt, this is a hybrid, nice conversation with our guests, but also we solicited questions from our audience.

Matt, what questions do you have for our man here?

Yeah, so a load of Patreon patrons came through with some great questions.

So Shane McDaniel says, when you use long exposure detectors, how do you keep them in the same line of sight through the exposure so that all the data lines up given the Earth is rotating and the cameras in space have their own velocity, etc.

I don't know if this refers to a space mission or a ground-based telescope, but whatever it is, we have developed tracking on the skies has been on Earth.

We have what we call the polar axis of old style telescopes.

You'll see it on big axis pointed at the roughly the North Pole, which is Polaris at our time.

And the telescope spins around this with what we call sidereal rate.

And they also have other fine things like the auto guide, we have a special detector which is sensing starlight and would like nudge the motors left and right to keep things exactly in the center.

And for a space mission, it's similar techniques.

And plus in space, it's somewhat easier actually to track because you know they have less external forces, you're not necessarily like spinning with the earth itself, you're pointed at some direction.

Yeah, just to add some emphasis there, you mentioned sidereal time because I don't know that people know that the stars revolve around the Earth, if I may speak in that way, pre-Copernican, they revolve at a different rate than the sun does.

So the sidereal rate is the star rate, that the stars go around the Earth, and that's every 23 hours and 56 minutes.

The stars make 1 complete loop, whereas the sun makes 1 complete loop in 24 hours.

So yeah, so we got smart people figuring all that out.

But you know what my iPhone does today, is if I want to take a long exposure, it doesn't say, hold it really steady while I can do this.

No, it takes multiple exposures, multiple short exposures, and then in software, when the exposure is done, It registers the light in that image, stacks them, adds them, and that's my final photo.

And I don't even see the intermediate stages of it.

So that's another way to accomplish the same thing.

So Gaspar, what you're saying is, we know enough about the rotation of the Earth to compensate for it when we're taking long exposure photos.

Yeah, yeah, we have measured the spin of the Earth very well, so well that we actually even see, that's not something we correct for during the night, but strictly speaking we see when the Earth spins down or spins up due to changing seasons.

We are so good at knowing the rotation of the Earth, we can say when it's varying.

The Earth used to be our primary clock, right?

wouldn't know if the clock was varying if your clock itself was the foundation of your timekeeping.

So now you have to be able to keep time better than Earth does to then show that Earth is either speeding up or slowing down.

You can see my pottery on my website, cosmicmugs.com.

Cosmic Mugs, art that lets you taste the Universe every day.

This is StarTalk with Neil deGrasse Tyson.

Well, I'm going to combine a couple of questions because I'd love to do that.

So there's a question from Mark Bode, firstly from Boulder, Colorado, who says, is a question about the proliferation of low-Earth orbit satellites.

Since it doesn't seem like the rate humanity is launching these things will reduce anytime soon, What is the best way we can ensure the skies remain clear and free of light pollution to enable important activities, such as the search for extrasolar planets?

And then also Kevin Browning from White Deer, Texas says, How does low orbiting satellites and space debris interfere with the search for exoplanets?

What can ordinary people like myself who care about the night sky do to convince congress or companies like SpaceX to reduce light pollution and the number of orbiting satellites?

Okay so that's why you have to answer that in 3 sentences.

So actually first why don't you distinguish for us the difference between light pollution and satellite pollution, because it's not the same thing, is it?

I would say light pollution has a ground-based component, which is bright city lights, poorly designed lights going up in the sky and illuminating our atmosphere and the night sky making it brighter.

And the second component which is fairly new and unexpected so to say is light pollution coming from thousands or soon maybe tens of thousands of artificial satellites orbiting the earth, reflecting back light from the sun or emitting radio waves, which is also electromagnetic radiation.

To deal with the first 1, I would say technically, it's sort of a trivial thing.

And there are many other things in the history of humanity which were trivial and we have not been dealing with it.

But you know, to give some hope, I think some of them were dealt with.

So we used to pollute our rivers far more than we do now.

We used to pollute our atmosphere with Freon and with other pollutants that would decrease like...

Smoke stacks, you know, I grew up, I have to brush ash off my shoulders because every apartment building burned its own trash at certain times of day.

So yeah, When I grew up, the sky was bad for multiple reasons.

So, you know, London used to be covered in soot for centuries, and now it's sort of clean compared to that.

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Cosmic Queries – Discovering Exoplanets with Gáspár Bakos