Artist’s impression of a young gas giant planet still swathed in traces of a late-stage protoplanetary disk
A long time ago, in a solar system far, far away, a planet was born. Since its momentous birth, it has grown and grown and grown, far surpassing its distant cousin Earth in size.

But even though astronomers knew the giant heavenly body existed, there was no direct evidence of that fact. Scientists could only make inferences about it based on the information they had at their disposal.

Until now. In 2015, Amherst Assistant Professor of Astronomy Kate Follette and a team of colleagues from other institutions were able to image that “baby planet”—called LkCa15b and pronounced “lick calcium 15 b”—in its still-formative state. They are the first group of scientists to ever directly image a planet still in the process of forming, otherwise known as a protoplanet.

Kate Follette using a telescope on the Amherst College campus
Follette and her colleagues published a paper reporting a second protoplanet in another star system in The Astrophysical Journal Letters this past August.

“This is at the very hairy edge of what we can do,” Follette said recently, adding that when she first saw the image of LkCa 15 b she found it hard to believe what was in front of her eyes. “It’s a small signal. I talked myself into and out of what I was seeing.”

Follette explained that planets in other solar systems, called exoplanets, behave as Earth does and orbit around stars. (In Earth’s solar system, that star is the sun.) Planets like LkCa15b are hard to see directly, since they are very far away, and the brilliant light emitted by the stars that the exoplanets orbit make it difficult to see anything close to them. As a result, scientists are often forced to use other, indirect ways to detect and study these distant bodies. One common method, for example, involves measuring the dimming of a star as an exoplanet passes between it and the Earth.

planet formation model known as core accretion
Being a part of a team that imaged and is learning more about LkCa15b is very exciting, said Follette. She and her colleagues were able to estimate the planet’s mass to be a couple of times that of Jupiter, the largest planet in our solar system. LkCa15b is approximately 450 to 500 light years away from and probably 20 times the radius of Earth. And even though the planet is still forming, it probably won’t get much bigger, relatively speaking. “We’ll just have to keep watching it,” she said.“If we take all the technologies my colleagues, students and I have been trying to improve on the ground and we apply them to a space-based imaging mission, for example, we could conceivably get to Earth-like planets in the not-too-distant future,” she said, adding, “I’m not optimistic of that happening in the next decade or two, but perhaps within my lifetime.”

In response to a reporter’s “I have to ask it” question of whether or not she believes in the existence of other life forms in the universe, Follette said she couldn’t provide an answer any time soon, because such a response would just be hypothetical.

“Of course, exoplanets were purely speculative until 1995,” she mused. “So who knows what we will find in the future?”

Credit for artists' renditions: NASA/JPL-Caltech