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Seeing planets like never before

Until the end of the 20th century, ours was the only planetary system known. We now know of more planets outside our solar system than within it.  Astronomers have now located more than 1,000 planets orbiting stars other than our own, and the latest observations are starting to reveal what these planets are like. The American Museum of Natural History-led Project 1640 is at the forefront of this research. The project’s advanced telescope instrumentation can spot chemical fingerprints that will help characterize how exoplanets form, evolve, and differ from familiar planets closer to home. Created by American Museum of Natural History.

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Video transcript

The idea that planets orbit other stars than the Sun is nothing new. The Greeks back thousands of years ago discussed this idea. But the scientific evidence for it really didn’t come about until the early to mid-90’s. At this point, we know of the existence of roughly a thousand planets orbiting stars other than the Sun. We know about their mass distribution, the variety of orbits that they occupy. But we know very little about the chemical composition of their atmospheres, and we know nothing of the surfaces of the planets that we have detected. Project 1640 is called that because we observe wavelengths that are just redward of what a human eye can detect, in what we call the near infrared, and the wavelength of light at which the project can see the faintest planets is actually 1,640 nanometers. The specific goal of this project is to try to see and study in detail as many planets as we can. There is such a broad range of possible planets out there with a wide range of properties that people really didn’t imagine even just a few years ago. For example, there could be a world of water, or there maybe a giant lava world, or a planet with a huge gas layer on top of it so that we’d never see the surface. We have no idea. And I think by expanding the types of planets that we know of people can come to a far better understanding of ourselves and how we fit into this Universe. The problem is that these planets are very, very faint, and they’re right next to extremely bright stars. So the whole trick here is removing the light of the star without destroying the light of planet. A little more. There we go. We’ve just filled the infrared camera with liquid nitrogen in in order to cool down the detector so that we can actually see planets and stars, and this is all in preparation for installing the instrument on the telescope tomorrow. Here we go. Are we high enough to push in? And this Ethernet is labeled DAK USB. It’s a USB extender. Trying to find one of these exoplanets takes a lot of advanced technology. Imagine a firefly flying around a lighthouse. To be able to see the firefly, we have to block out the light from the lighthouse. And we use a coronagraph to do that, and that’s a very high-tech version of putting your thumb over the lighthouse. But you’re trying to do this through the Earth’s atmosphere. And if you’ve ever looked across a hot road in the summertime—that’s the distortion in the atmosphere that we’re trying to take out using our adaptive optic system. We also have a wave front control system that helps to stabilize the telescope itself. All those have to work together perfectly to give us the suppression of the starlight we need to let us pull out the faint images of the planet itself. So I managed, I think, to get four of the objects we wanted in. O.K. And there’s just one decent looking survey star. Right. Observing at Palomar is always a race. You’re racing against the Sun. The moment the Sun goes down, you’re just going bang, bang, bang from exposure to exposure to target to target and trying to collect as much data as possible. All right, the next star, Gene, is 40273. O.K. Thank you, moving. We want to choose fairly nearby stars so the planet is separated as widely as possible from the star. It’s awfully close to the star. It could just be too close? It’s possible. We want fairly young stars so that the planets are still bright from their residual heat of formation. Image processing sequence complete, awaiting instructions. And our goal, long-term, is to observe about 150 to 200 stars and start And start to really characterize these exoplanet systems for the first time. All right, so here’s the first image of the star. We collect 32 different images all simultaneously, but each image is at a slightly different wavelength of light. What we can then do is make a movie of these things. A movie not in time but in color. And what you see as you go from short wavelengths to long wavelengths is speckles radiate outward from where the star is. A real planet or object will stay stationary in those images. Do you see it? Yeah, there’s something right here. Yup. So, it’s clearly not moving with the speckles. Once you’ve got lots of data like this you can see your little planet. But you can also measure how bright it is at each wavelength, and that’s the spectrum of the planet that allows you to determine the chemical composition of it. So if you see a dip somewhere at a particular wavelength, you can identify what molecule caused that because molecules absorb at very specific well known and well cataloged wavelengths of light. Yeah, I think the seeing is not bad, actually. So one of the high points of Project 1640 so far has been our observation of the planetary system with the romantic name of HR 8799. What we’re able to do is take a snapshot showing all four planets at the same time, and in each case be able to get a spectrum of all the planets and start to be able to do the characterization. And And our goal is to be able to repeat that many times over, finding new systems, characterizing them, and start to build up many, many family portraits of these new exoplanet systems. Alright, why don’t you bump it up to three? So, what do you have to do, add one more? Ultimately, the kind of research that we’re doing is a precursor to looking for planets similar to Earth. Perhaps ones the even support life. The question of whether life exists outside our solar system is so compelling that we’ll never stop searching until we’ve found an answer. But in the meantime we have a lot of worlds to study.