Ana Humphrey, a student at T.C. Williams High School in Alexandria, Va., won first place and was awarded $250,000 in the Regeneron Science Talent Search. (Chris Ayers/Society for Science & the Public)

In sixth grade, Ana Humphrey attended the nation’s oldest and most prestigious high school science competition and was inspired after speaking with a student who claimed the top prize that year.

Humphrey left that year with dreams of conducting her own research. On Tuesday night, at a black-tie gala inside a soaring hall at the National Building Museum in Washington, the 18-year-old from the city of Alexandria, Va., was awarded the $250,000 top prize at the Regeneron Science Talent Search.

“All I could dream of was being just like her, just doing research just like her,” she said. “I never thought that dream would include actually winning.”

Humphrey’s project sought to confirm the existence and probable location of exoplanets — planets outside our solar system — missed by NASA’s Kepler Space Telescope. The planets orbit stars beyond our solar system and are uncovered using a method that measures a star’s decrease in brightness when a passing body blocks its light, according to a project summary.

But some planets may not pass in front of a star from our viewpoint, or the planets are so small they don’t block enough light to be detected, Humphrey explained. Humphrey used mathematical modeling to determine as many as 560 missing planets and 96 key areas to search.

Adam Ardeishar, a student at Thomas Jefferson High School for Science and Technology in Alexandria, Va., won third place and $150,000 in the competition. (Chris Ayers/Society for Science & the Public)

“By learning about these other systems and figuring out how they form . . . we can understand a lot more about how our own solar system formed and what’s possible and what our place is in our universe,” she said.

Humphrey is the only student from T.C. Williams High School in at least the past decade to place in the competition’s top 10. Two other Northern Virginia students — Adam Ardeishar, who attends Thomas Jefferson High School for Science and Technology in Alexandria, and Carolyn Beaumont, a student at the private Potomac School in McLean — were finalists.

Ardeishar, who came in third and won $150,000, found a connection between a previously unsolved math problem called the “coupon collector problem” and extreme value theory, which is used to determine the likelihood of a maximal event, such as a bridge collapse.

Beaumont received fifth place and $90,000 for investigating how water affects the viscosity of magma, a key factor in the violence of volcanic eruptions.

In the past decade, just four other Virginia students placed in the science competition’s top 10. All attended Thomas Jefferson, an elite magnet school in the Fairfax County Public Schools system that enrolls students from several school districts.

Carolyn Beaumont, a student at the Potomac School in McLean, Va.,, won fifth place and was awarded $90,000. (Chris Ayers/Society for Science & the Public)

Thousands of students submit research projects to the competition each year. Forty finalists were invited to Washington, where they explained their projects to some of the nation’s top scientists and competed for more than $1.8 million in prizes.

Three other students from the Washington region — all from Montgomery Blair High School in Silver Spring, Md. — were among the 40 finalists.

Regeneron Pharmaceuticals, a biotechnology firm in Tarrytown, N.Y., began sponsoring the competition in 2017 and promised $100 million in scholarship money to winners over 10 years.

Humphrey, who plans to put her winnings toward higher education and more research, is the first Hispanic student to claim the science fair’s top award in two decades. One of the recurring themes during the teenagers’ week in Washington, she said, was the “strengths of immigrants and what they bring to this country, what they bring to science.”

“It just shows that you need a diversity of thought and a diversity of backgrounds to solve the world’s most challenging problems,” she said. “And you can’t do that without including everyone.”