To date almost 700 planets have been found that orbit other stars, and the numbers keep climbing. The question is, once you’ve found a new planet, what do you do with it?
This summer, doctoral student Knicole D. Colon of the University of Florida tried out two possible answers to that question—and one of her projects may help us better understand the chances of finding more truly Earthlike worlds across the galaxy.
First, it’s worth noting that a couple different techniques exist for finding extrasolar planets, or exoplanets. Both of Knicole’s targets were found because they transit, or pass in front of, their host stars as seen from Earth.
NASA’s Kepler space telescope is an ongoing mission that’s so far found 1,235 possible planets via transits. But the data can include false positives, requiring followup observations to confirm that the objects are actual planets. To date, Kepler’s confirmed planet count stands at 24.
Once an exoplanet is confirmed, even more observations can help astronomers paint a more accurate picture of the world and its chances for habitability.
For instance, from a confirmed planetary transit, the resulting dip in starlight can tell astronomers the size of the planet and how far it orbits from its star, which can in turn allow scientists to estimate the planet’s surface temperature.
Other planet-hunting techniques can then give mass, allowing for calculations of the planet’s density and thus best estimates for its composition.
What’s more, by observing a transit with the right instruments, astronomers can try to tease out what types of chemicals exist in a planet’s atmosphere. That’s because some of the starlight that reaches us would have been altered as it passed through the alien atmosphere.
Piecing together clues such as size, density, temperature, and atmospheric contents can help scientists figure out just how much a given planet resembles Earth.
For her recent work, Knicole wanted to 1) help confirm the existence of super Earth-size to Neptune-size planets in Kepler’s haul of candidates and 2) search for methane in a super-Earth’s atmosphere.
But to do all this, Knicole first had to travel to an “alien” realm right here on Earth: the top of a high, remote mountain on the Spanish island of La Palma in the Canary Islands.
With funding from the National Geographic Society’s Committee for Research and Exploration Young Explorers program, Knicole was able to conduct observations with the OSIRIS instrument on the 10.4-meter Gran Telescopio Canarias, currently the largest single-aperture optical telescope in the world.
The data is still being processed for public consumption, but Knicole was able to answer a few questions about her scientific adventure:
What was it like going to La Palma?
It was an adventure in itself just traveling there! The trip involved four separate flights, crazy taxi drivers, and driving up the steepest mountain I’ve ever been on! There are so many twists and turns going up the mountain that you just *know* you are going to go flying over the cliff on one of the turns … and yet, by some miracle, you get to the top of the mountain safely! Once you are there, you know that the 24+-hour trip it took to get there was completely worth it. You feel like you are on top of the world, and you have such an amazing view of both the ocean and the sky. You can even see some of the other islands in the distance. It truly is breathtaking. Not to mention that you see several awesome-looking telescopes on the mountaintop!
Was it weird using such a friggin’ huge telescope?
I think it was a pretty humbling experience. As an undergrad I got to spend a summer doing research at Arecibo Observatory [in Puerto Rico], which was amazing because I got to visit the largest radio telescope in the world and see it in action. Being at the GTC was completely different, though, because I was at one of the largest optical telescopes in the world and this one I got to use for my own personal research! I got to decide what target to look at, where to look, when to look … basically this huge telescope was at my command! Not only was that awesome, but seeing the telescope in action was like looking at a truly marvelous piece of human technology. When you don’t see these kinds of things in person, it’s hard to fully appreciate them.
Did you have any unexpected challenges during her trip, or any surprising experiences?
For the most part the actual travel to and from La Palma went smoothly, which was surprising in itself. All in all, I’d say that things went as expected during the trip. There were some minor technical issues to deal with, and I had to make some quick decisions on how to handle those issues or else we may not have been able to acquire any data during my trip (which would have been a huge disappointment of course). That did make me a bit nervous because I hoped I was making the right decision at the time (and looking back at it now, I’m confident I did). But that is one thing that was emphasized to me during my trip—you do not want to risk wasting time at a 10-meter telescope!
What do you mean by “technical issues”?
One particular issue we had was that one of the mirror segments of the primary mirror was misaligned. The telescope’s primary mirror is composed of 36 hexagonal components, and all those components are supposed to be aligned so that they focus the incoming light to one location. However, the night of one of our observations one of the segments was misaligned so that, on the images we took, the light from that mirror segment was not sent to the same location as all the rest of the segments. When we looked at images of our target star and nearby stars, we noticed a small blip to the lower right of every star in the image. When we realized what was causing this problem, we tried to reset the system so that mirror segment would realign itself. Unfortunately, that did not work. So, after considering our options, and to avoid losing any more observing time, we decided that because the small blip was still fairly close to the star, we would still be able to get all the light we needed for our observations. From this, we went ahead with the observations. I would say this type of problem was not necessarily solved, but it was something we had to deal with by weighing the pros and cons of getting observations with this type of issue present. In the end, I think it all worked out okay, but it was still stressful at the time!
Do you think we’ll find a habitable “other Earth” in your lifetime?
This is a very interesting question. Do I think we’ll find a habitable “other Earth” in my lifetime? Yes, I do. I think we will be able to find an Earth-size planet in an Earth-like orbit around a sun-like star sooner than later in my lifetime. I think it will be very difficult, but not impossible, to determine if it has an Earth-like atmosphere and composition and is therefore habitable, but this could still happen in my lifetime. What I think is very tricky and may or may not happen in my lifetime is finding an *inhabited* Earth-like planet. That would be a truly incredible discovery and I really hope such a thing happens in my lifetime. Unless, of course, the inhabitants are hostile and decide to come to Earth!!!