As a young girl growing up in small-town Vermont, Aki Roberge dreamed of other worlds.
An avid science fiction fan, she wondered if the kinds of planets she saw in the “Star Wars” movies, with their varied climates and cultures, creatures and civilizations, might really exist.
Today, and for more than a decade now, she actually explores such possibilities, searching not for parched Tatooine or ice-clad Hoth, but for real exoplanets — planets orbiting other stars.
Dr. Aki Roberge, a research scientist in NASA’s Exoplanet and Stellar Astrophysics Lab at the Goddard Space Flight Center in Maryland, right outside Washington, D.C., will talk about her life, her work and the latest breakthroughs in this relatively new branch of astronomy at 7 p.m. Friday. It’s part of Wyoming Stargazing’s “The World Above the Tetons” speaker series.
Giordano Bruno (1548-1600), an Italian monk, philosopher, mathematician, poet and early adopter of the heliocentric model of our solar system, took Nicholas Copernicus’ revolutionary idea a step further in 1584 when he speculated that our infinite universe contained “an infinity of worlds of the same kind as our own.”
Sir Isaac Newton (1642-1726) said something similar 225 years later in an addendum to his opus, “Principia Mathematica,” writing, “And if the fixed stars are the centers of similar systems, they will all be constructed according to a similar design” as our home star system.
But it was another 225 years, including a century or so of false starts and near misses, before the first confirmed detection of an exoplanet: In 1992 Aleksander Wolszczan and Dale Frail, working at the dearly departed Arecibo Observatory in Puerto Rico, found two planets orbiting a pulsar 2,300 light years away in Virgo. A third was discovered in 1994, and the following year the first exoplanet was found orbiting a “main sequence” star — a star more or less like our own sun — and a new branch of astrophysics was off and running.
As of April 1 astronomers has confirmed 4,704 exoplanets in 3,478 systems. Early discoveries were gas giants, up to 30 times the size of Jupiter, in tight orbits that caused their stars to dim periodically as they passed across them and even wobble due to gravitational interplay. In February 2014 NASA announced that with its Kepler Space Telescope it had found a whopping 715 exoplanets in 305 systems, including many closer in size to Earth. Exoplanets have been detected orbiting Alpha Centauri, our cosmic next-door neighbor, and in February 2018 the Chandra X-ray Observatory found evidence of planets in another galaxy.
This “wonderful diversity” of exoplanets is part of what fascinated Roberge.
“Before the first were discovered … it was totally the realm of science fiction,” she said in a recent Zoom call, in which she used a filter to make it look like she was sitting in the lounge of Han Solo’s Millennium Falcon. “Since then it has become a new and growing field of astronomy, and to the delighted surprise of astronomers they are much more common and more diverse than we expected.”
We still don’t yet know if there are any truly Earth-like planets out there, she noted, but ever-advancing technology is bringing us closer to being able to find them, if they are out there, not to mention adding volumes of new information to what we know about stellar and solar system formation.
“In the coming years we’re going to be able to start moving from the discovery phase ... to where we probe them and see what they’re like,” said Roberge, who helped conceive of one of the instruments that may make that happen, the Large UV/Optical/IR, or LUVOIR, telescope.
If NASA approves LUVOIR and it is built and deployed — the 2030s is the target date — it will follow up on work begun by the Hubble, Kepler and Webb space telescopes. Designed specifically to look for and study Earth-like planets (among other things), it will be able to analyze the atmospheres of exoplanets, looking for “biosignatures,” things such as oxygen and methane that can be byproducts of photosynthesis and other biological processes.
“We’ll be looking at planets at really nearby stars,” Roberge said, “tens of light years away, in our solar neighborhood.”
The detection of water vapor and molecular oxygen “would be, like, ‘boom!’” she said — a significant clue that life might have evolved there.
“I’m an optimist on the question of life on other worlds, simply because planets are common,” she said. “There’s a lot of territory out there that can be inhabited, and the ingredients of life on this planet are pretty common, among the most abundant elements of the universe. We don’t know how life arose on this planet — don’t know how hard it is — but planets seem common and the necessary elements are common … and if we find out that Earths are rare, that’s important info, too. No matter what we find we’ll learn about something important.”
Wyoming Stargazing’s speaker series continues through the spring, with Dr. Suzanne Ramsay of the European Extremely Large Telescope set for May and Dr. Michela Negro of the Fermi-Large Area Telescope coming in June. All events are free, though the nonprofit appreciates donations. For information and to tune in to Friday’s talk with Roberge, go to WyomingStargazing.org/speaker-series. ￼