NASA Fermi Space Telescope Data Adds Up All Of The Universe's Starlight

NASA's Fermi Gamma-ray Space Telescope provided data used to measure all of the starlight our universe produced over 90-percent of its history, the space agency has revealed. Scientists working on the project looked at the gamma-ray output from distant galaxies, using that to estimate star formation rates. This is the first time researchers have measured all of the starlight produced over the history of the observable universe.

The research comes out of Clemson University's College of Science, where astrophysicist Marco Ajello and postdoctoral researcher Vaidehi Paliya worked with colleagues to analyze Fermi telescope data. The work looked over the history of star formation covering 90-percent of the universe's history, finding that 4x10^84 particles of visible light were emitted by stars, producing starlight.

In talking about the research, Ajello said:

From data collected by the Fermi telescope, we were able to measure the entire amount of starlight ever emitted. This has never been done before. Most of this light is emitted by stars that live in galaxies. And so, this has allowed us to better understand the stellar-evolution process and gain captivating insights into how the universe produced its luminous content.

Despite the huge photon number, Earth still gets the majority of its light from the Sun due to the vast size of the universe. Starlight that reaches Earth from beyond our galaxy is as dim as a 60 watt light viewed from more than two miles away, leaving us with a dark night sky and small, bright stars visible in the distance.

NASA explains in the video above how Fermi works and why its data was able to help the researchers analyze the universe's starlight. In addition to its milestone research, the study also independently confirms past star formation estimates, according to the space agency, that were based on deep galaxy surveying missions.

The findings will help improve future research into stellar evolution.