The Moon shines brighter than the sun and would always look full when seen through NASA’s Fermi Gamma-ray Space Telescope.
“Gamma-ray observations are not sensitive enough to clearly see the shape of the Moon’s disk or any surface features. Instead, Fermi’s Large Area Telescope (LAT) detects a prominent glow centered on the Moon’s position in the sky,” NASA said in a statement.
Mario Nicola Mazziotta and Francesco Loparco, both at Italy’s National Institute of Nuclear Physics in Bari, have been analyzing the Moon’s gamma-ray glow as a way of better understanding cosmic rays.
“Cosmic rays are mostly protons accelerated by some of the most energetic phenomena in the universe, like the blast waves of exploding stars and jets produced when matter falls into black holes,” explained Mazziotta.
Cosmic rays interact with the powdery surface of the Moon, called the regolith, to produce gamma-ray emission.
Although most of these gamma rays are absorbed by the Moon, some bounce off its surface.
Mazziotta and Loparco organized data for gamma rays with energies above 31 million electron volts — more than 10 million times greater than the energy of visible light —showing how longer exposures improve the view.
Via #NASA - If we could see the universe the way the .@NASAFermi Gamma Ray Telescope does, our moon would glow brighter than our Sun. https://t.co/dn9XPeDIZa pic.twitter.com/E9wECEzD9d— Gene J. Mikulka (@genejm29) August 16, 2019
“Seen at these energies, the Moon would never go through its monthly cycle of phases and would always look full,” said Loparco.
The series of images released by NASA show the Moon shining brightly in gamma rays.
“Each 5-by-5-degree image is centered on the Moon and shows gamma rays with energies above 31 million electron volts, or tens of millions of times that of visible light. At these energies, the Moon is actually brighter than the Sun. Brighter colors indicate greater numbers of gamma rays,” the statement said.
Longer exposure, ranging from two to 128 months (10.7 years), improved the view.
Referring to its Artemis program of sending humans to the Moon by 2024, NASA said the gamma-ray observations are a “reminder that astronauts on the Moon will require protection from the same cosmic rays that produce this high-energy gamma radiation.”
With the eventual goal of sending astronauts to Mars, understanding various aspects of the lunar environment assumes even more significance, the agency said.