How Dark Is Space?

Tod Lauer, NSF’s NOIRLab

Looking at the sky on a clear moonless night, one sees stars against black space. Powerful telescopes reveal faint stars and galaxies strewn between the bright stars, but still set against a black background. But we can ask, "Is space really, truly, completely dark?"

Unfortunately, looking for a faint glow from the universe itself is tricky from the vantage point of the inner Solar System, where sunlight is scattered by interplanetary dust. NASA’s New Horizons space probe, however, is now more than 50 times further away from the Sun than Earth, and its background sky is much darker than the one the Hubble Space Telescope observes.

Join Dr. Tod Lauer as he describes an intriguing experiment that employed this perfect camera for gauging the blackness of space, and found evidence for an unknown source of light from the universe, itself.

Host: Frank Summers, Space Telescope Science Institute
Recorded live on Tuesday, October 5, 2021
More information: www.stsci.edu/public-lectures