PORTLAND – Greely High School student Morgan MacLeod has earned a star. Make that two stars.

The 17-year-old Cumberland resident is being honored for discovering two variable stars, which fluctuate in brightness. He was using only an amateur’s telescope when he found them while searching star clusters in the constellation Cassiopeia.

“Variable stars are not that easy to discover,” said MacLeod’s science teacher, Robert O’Neill.

“It’s easy to find stars, but it’s very difficult to find stars and then analyze their light curves and their temperature curves to prove that they are a specific type of variable star. And that’s what he did,” O’Neill said.

MacLeod used a digital camera to photograph the stars through a telescope, then examined the photos using special software. It was all amateur astronomy equipment that could be purchased in a store for about $4,000.

“My parents were really nice in helping me buy a lot of it,” MacLeod said. “I had to pay for part of it, but they helped me out a lot.”

His work makes MacLeod one of six finalists for a $100,000 grand prize in the Siemens Westinghouse Competition in Math, Science and Technology early next month in Washington. It is considered the nation’s most prestigious high school science competition.

He won the top individual prize at the New England Regional finals held at the Massachusetts Institute of Technology in Cambridge on Saturday. The prize came with a $3,000 scholarship.

One of the stars MacLeod discovered was a pulsating star, “which means that it’s expanding and contracting, and that’s causing the change in brightness that we see,” he said.

“It’s an unstable star, basically, and that’s causing it to oscillate,” said MacLeod, who puts Bowdoin on his short list of colleges where he’ll apply.