Adam Kraus and his colleague, Michael Ireland from Macquarie University and the Australian Astronomical Observatory, used Keck telescopes on Mauna Kea to find the planet being formed from gas and dust, the Institute for Astronomy said Wednesday.
LkCa 15 b is 450 light years away from Earth and is the youngest planet ever found.
Kraus presented the discovery Wednesday at NASA's Goddard Space Flight Center in Maryland. Kraus and Ireland's research paper on the discovery is due to appear in The Astrophysical Journal.
Scientists hadn't been able to see such young planets before because the light of the stars they're orbiting outshines them.
"In the past, you couldn't measure this kind of phenomenon because it's happening so close to the star. But, for the first time, we've been able to directly measure the planet itself as well as the dusty matter around it," Kraus said in a statement.
Kraus and Ireland used mirrors to cancel out the bright light of the star near LkCa 15 b.
"It's like we have an array of small mirrors," Kraus said. "We can manipulate the light and cancel out distortions."
The astronomers found the planet while surveying 150 young dusty stars. This led to a more concentrated study of a dozen stars.
The star LkCa 15 - the planet is named after its star - was the team's second target. They immediately knew they were seeing something new, so they gathered more data on the star a year later.
"We realized we had uncovered a super Jupiter-sized gas planet, but that we could also measure the dust and gas surrounding it. We'd found a planet at its very beginning," Kraus said.