With the internet, it doesn’t take a Ph.D. in astrophysics to help find new worlds outside our solar system.
For the first time, new planet candidates have been identified with the help of the public’s analysis of NASA data. Anyone can join this effort, called Planet Hunters, for free and start helping real astronomers weed through data that might signal a never-before-seen planet.
Computer algorithms that the pros use do the job of sorting through data from deep space with precision and speed, but sometimes humans can do it better.
“A lot of times, we don’t know to anticipate in advance something unusual in the data. And so that’s clearly where the Planet Hunters, the public, [have] been coming in,” said Debra Fischer, professor of astronomy at Yale University and co-founder of Planet Hunters.
So far, there are about 40,000 users of Planet Hunters across the U.S. and about 90 other countries. It’s intuitive and simple enough that even a child could use it. Teachers are already using it in the classroom, Fischer said.
“It’s a perfect opportunity for even children to become involved, and to really learn what the scientific process is, what the scientific method is, and that thrill of discovery at an age where they still have the opportunity to make decisions about their future” said Natalie Batalha, co-investigator for NASA's Kepler mission, which has discovered more than 1,200 candidate planets so far.
All you have to do is sign up with Planet Hunters and start answering questions about graphs, which represent data about light from distant stars. The website guides you through what to look for – the dips and v-shapes corresponding to a dimming of light may mean a planet has transited, or passed in front of a star during a certain time period.
In the first test batch of data, users had classified about 3,500 transits. Fischer enlisted undergraduates to help look at every single one of them, passing the best ones on to the graduate students who would pass them to the rest of the team, and they boiled down the list to 40 that looked the most like the signatures of planets. Of the 10 that they sent to the Kepler group, two turned out to be good candidates for planets.
One is a “super Earth” with a radius about twice that of our planet. Without knowing its mass, scientists can’t say anything about its composition. The other is a Saturn-sized object, Fischer said.
Computer algorithms had seen both of these celestial objects, but had misclassified them.
Planet Hunters had also identified the recently-announced planet nicknamed Tatooine, the first planet confirmed to orbit two stars at once. The citizen science effort helped find it four months ago, independent of the NASA Kepler team.
The Kepler team had actually published a catalog of possible eclipsing binary systems in March, so technically the pros were still first. But Batalha says it’s not such a cut-throat competition.
“It doesn’t matter who was first,” Batalha said. “Those discoveries were being made, and that process – going through that process and experiencing that thrill – that’s what’s important.”
The Planet Hunters expert team, a collaboration between astronomers at Yale, the University of Oxford and the Adler Planetarium in Chicago, just sent the next top 10 over the Kepler, and it looks like seven may hold up as candidate planets, Fischer said.
Scientists have confirmed the existence of more than 680 planets outside of our solar system, according to NASA's PlanetQuest website. In order to be more certain about the two new candidates from the Planet Hunters, scientists need to use a method called Doppler spectroscopy, a method of measuring the mass of these objects.
Stars with planets appear to wobble toward and away from the observer - meaning a change in radial velocity - and this effect is larger when the planet is either bigger or closer to the star. Measuring light from the nearby star and its radial velocity helps scientists determine whether an object is indeed a planet, as well as how dense it is.
Fischer is fairly confident that the two new candidates spotted by Planet Hunters are “bona-fide” planets.
“There are 4 million classifications, and out of that came two planets so far. There will be there more, but still, it gives you some sense of the scale of the problem." Fischer said. "It’s a lottery ticket, I guess."