An Astronomer’s Quest: Searching for the Known Unknown

Cullen Blake was smitten by the sky when his third-grade class studied stars and planets. “It piqued my curiosity,” he recalls, adding that his intellectual trajectory was influenced by the 1995 discovery of an exoplanet, the first planet known to orbit a star outside our solar system.

As an assistant professor of physics and astronomy and a NASA Nancy Grace Roman Fellow, Blake’s stargazing is rooted in science. But his sense of wonder has not waned. “One of the most exciting scientific realizations in some time is the notion that our solar system is neither special nor rare,” he remarks, “and that’s an important take-away.”

Blake’s primary research interests encompass the search for Earth-like exoplanets orbiting low-mass stars, studies of brown dwarfs—celestial objects larger than planets but smaller than stars—and time-domain astronomy, which focuses on how an object changes over seconds to hours.

“There are only so many bright stars in the sky, but stars come in a surprisingly wide range of sizes and masses,” Blake says. “In the past 25 years, the focus in the search for exoplanets has been on stars that are like the sun. But they are only the tip of the iceberg. Many other populations of stars are largely unexplored.” 

Blake concentrates on the search for Earth-like exoplanets located in the habitable zone—the area around a star in which a planet absorbs the same amount of radiation from its host star as Earth absorbs from the Sun, which may make them neither too hot nor too cold to support life. As an observational astronomer, one of Blake’s main goals is to develop techniques to measure and characterize Earth-like planets orbiting low-mass stars.

“In the last hundred years, astronomical data has been mainly static in time, not capturing the rapid variability of stars or distant galaxies,” Blake says. “Digital cameras have dramatically enhanced the quality of available data. Rather than applying to a committee that doles out telescope time, we use Internet-enabled telescopes that operate on every clear night. That’s much more efficient science than is possible with person-operated telescopes.”

Blake, who counts Hawaii’s Mauna Kea Observatory and Mt. Hopkins in Arizona among his favorite places his work has taken him, has helped design a telescope capable of detecting “momentary explosions—things that go bump in the night.” Supported by NASA, his current project involves developing and assembling an instrument and telescope. Working together, these high-tech tools will detect planets whose presence is inferred from the slight movement of the parent star that is caused by the planetary companion. This work is largely designed to complement NASA’s Transiting Exoplanet Survey Satellite (TESS), which will search the entire sky for planets outside our solar system.

“It will be a long time before we have definitive evidence of planets having atmospheric compositions indicative of the presence of life, but we are developing a better picture of how planets form and where they come from,” Blake says. “I fully expect the next few decades will be exciting for this field, especially in terms of studying the atmospheres of exoplanets.”