Four astronomers at the Space Telescope Science Institute in Baltimore, Md. are on two teams sharing the 2007 Gruber Cosmology Prize for their discovery that the expanding universe is accelerating under a mysterious cosmic force called dark energy.
The astronomers are Andrew Fruchter (top left), Ron Gilliland (top right), Nino Panagia (bottom left), and Adam Riess (bottom right).
Gilliland and Riess are on the High-z Supernova Search Team led by Brian Schmidt of the Australian National University. Fruchter and Panagia are on the Supernova Cosmology Project led by Saul Perlmutter of the University of California at Berkeley.
The two teams independently found that the universe is expanding at an ever faster rate.
To be able to measure the universe's expansion rate, now and at various times in the distant past, the astronomers needed standardized light sources. These sources have to be very bright ones that would be visible to Earth-based telescopes despite being billions of light-years away and billions of years old.
The standard light sources they used were exploding stars called Type Ia supernovae. The researchers used the unique sensitivity of NASA's Hubble Space Telescope to make precise measurements of these distant supernovae; a task that would have been impossible with only ground-based telescopes.
The $500,000 prize will be shared by Schmidt, Perlmutter, and their two teams. The prize will be awarded at the University of Cambridge on September 7.