Exploring the existence of exoplanets

By Gianluca D’Elia

Less than two weeks ago, a team of astronomers pointed the Hubble Space Telescope toward a solar system over 4,000 light years away, hoping to confirm the existence of a distant exomoon orbiting an exoplanet — that is, moons and planets outside of Earth’s solar system.

Alex Teachey, a Columbia University graduate fellow who is working on the research team, spoke about his research as part of the science department’s Science Friday series on Nov. 3.

In July, Teachey and his team suggested the possibility of a moon called Kepler 1625 b-i circling a planet outside our solar system after analyzing transit signals, or the passing of one celestial body across another. He said the planet is most likely the size of Jupiter and that its moon is the size of Neptune.

“It’s a crazy feeling to have your observations made by a million-dollar instrument hurdling through space,” he told a lecture hall full of science majors. “But the cool thing about physics is that you can make predictions about the future.”

The telescope took 233 snapshots of different regions of the sky to see transit signals, Teachey said.

“Whenever we’re looking at our solar system, we compare it to others,” Teachey told students. “Exomoons are a piece of that puzzle. In the outer of our own solar system, there are lots of moons. So what if others don’t have lots of moons? Until we observe, we don’t know. Maybe our solar system has had some sort of unusual history.”

Even though exomoons and exoplanets may be galaxies away from here, Teachey said exomoons are important to learn about.

“It takes a special set of circumstances for life to arise,” Teachey said. “The Milky Way has hundreds of billions of stars. Even if the rising of life is a one-in-a-trillion event, it’s still life.”

Assistant professor of physics John Bochanski expressed strong appreciation for Teachey’s work.

“[Teachey] is doing cutting-edge work on searching for exomoons, and I hope that he will discover the first one,” Bochanski said. “Finding a moon around a planet around another star will tell us a lot about just how common these systems are, and place our Moon in a greater context.”

Teachey also insisted that students stay tuned to the news as his team gets closer to finding out whether the exomoons exist, adding that the relationship between scientists and journalists can sometimes be difficult when it comes to reporting on new discoveries.

When the suggestion of Kepler 1625 b-i first came about in July, Teachey said his team has remained skeptical about the moon and planet’s existence until they can make further observations — they just started to make those observations last week.

“We didn’t want this news to get out because we weren’t ready to announce it — because we hadn’t even confirmed it,” he said. “We didn’t want to cry wolf. But it turned out someone spotted it, tweeted about it, and then a journalist said they wanted to write about our moon, and we said, ‘please don’t,’ but they wrote an article about it anyway, so we scrambled to get our paper out.”

Even before getting results on whether the exomoon exists, Teachey said there has already been extensive media coverage of his team’s research around the world, reaching as far as Poland and Estonia.

Leaving his advice for aspiring scientists, Teachey said, “You gotta be hard-nosed about the data and follow it wherever it leads. I don’t think we got it wrong. We did the best we could and we’ll report it accurately, whatever happens.”

Teachey also emphasized the importance of studying the universe beyond Earth’s solar system.

“It feels like we’re not part of the universe, but it’s not true,” he said. “We’re immersed in it.”

The Science Friday series will resume next semester, Bochanksi said.