Text on screen: Seven Earth-sized planets were discovered orbiting a nearby star. Tell us about these exciting new results!
Well we are very excited because NASA’s observatories are basically revealing a star system with seven Earth-sized planets orbiting the star.
These were detected by the Spitzer Space Telescope and now we are doing follow up studies with the Hubble Space Telescope.
It is the first time we’ve seen a system like this, with this many Earth-sized planets, orbiting a star.
Text on screen: These extrasolar planets are so far away. How can we tell if they are similar to planets in our solar system?
Well, looking at exoplanets – these planets around other stars – is a bit like detective work. They are so small next to a bright star that it is hard to tease out information unless you do it incrementally.
So what we can tell right now is that these planets are in fact similar to Earth in size and we can tell that some of them may be similar to Earth in its composition – doing kind of crude studies of the density of these planets.
We’re also using the Hubble Space Telescope right now to do follow up observations of the atmospheres of some of these planets to see the compositions of the atmospheres and wondering,
trying to find out if maybe there may be water in the atmospheres to see if they are similar to our own Earth’s atmosphere. So we are taking this one step at a time.
Text on screen: What does Hubble look for when it studies an exoplanet’s atmosphere?
So, what Hubble can do is actually tease out some of the components of the atmospheres of these planets orbiting this other star in the TRAPPIST system.
When the planet orbits around its parent star they happen – these planets happen to orbit in the plane, along out line of sight.
So, when that planet goes in front of the star some of that star light goes through the outer limbs of that planet’s atmosphere on its way to our Hubble Space Telescope and we can tell by what’s absorbed from that atmosphere – out of that star light – we can tell what’s in that atmosphere.
And sometimes we might see things like water vapor or other elements or molecules that give us more information and that’s what we are curious about. We want to know whether these planets have atmospheres similar to Earth’s or different from Earth’s.
Text on Screen: When the Hubble Space Telescope launched in 1990, we didn’t even know there were planets beyond our solar system. What is the iconic telescope’s role in studying exoplanets?
Sure, so Hubble was designed decades ago when we didn’t even know that there were planets orbiting other stars. Since Hubble’s launch there’s been an explosion of detection from other telescopes of planets orbiting other stars – these exoplanets.
Hubble is not really designed to discover these planets around other stars, but what Hubble is good at is looking at some of them with detail through something we call spectroscopy – which is the science of taking that light, spreading it out into its constituent colors and from this we can tell something about the composition of the atmospheres of these exoplanets.
Hubble was the first telescope to really use this technique of transit spectroscopy to tease out elements in an exoplanet atmosphere.
This is the technique of looking at light as it comes through the outer atmosphere of a planet that’s orbiting in front of its parent star on its way to our telescope and seeing what’s absorbed by the atmosphere.
So, Hubble detected things like sodium and other elements in an exoplanet atmosphere and was kind of the pioneer in that. Since then Hubble has become a powerhouse, for looking for molecules like water vapor in atmospheres of exoplanets that are detected and trying to help us understand the character of some of these exoplanets.
Because we really want to know if any of them are similar to Earth or if most of them are different and what makes a planet habitable. All of these pieces of information from different telescopes come together to give us a more complete picture of what we’re discovering.
Text on screen: Searching for habitable worlds outside our solar system sounds like science fiction, but it is a growing area for NASA. How will future mission search for Earth-like planets?
Well we are so excited about what we are learning about these extrasolar planets or exoplanets based – both on some of the discoveries that have already been made with telescopes on the ground and space telescopes like Kepler and now with the Spitzer Space Telescope.
We’re using Hubble now to analyze the atmospheres of many of these exoplanets and in the future – the near future – we’re looking forward to new space telescopes that will give us even more information.
Next year we are looking forward to something called TESS, which is the Transiting Exoplanet Survey Satellite mission which will actually look at many of the nearby, bright stars to our own solar system to see if there are planets orbiting those stars.
And then the James Webb Space Telescope, launching at the end of next year, will be a powerhouse observatory for many kinds of astrophysics, but one thing it will be good at is looking at the atmospheres of some of these exoplanets in infrared light.
So, that will give us another piece of information that we can add in to Hubble, Spitzer, the ground based and the Kepler work to give us a more complete picture of what these objects are really like and if any or many of them could be potentially Earth-like or habitable we need all of this information together.