They measure the darkness of space

Is space completely dark? Not really. Even in the emptiest regions of intergalactic space, it is not completely dark; there is some light, but it is too weak for the human eye to detect. Recent research has determined the level of light in space in the darkest areas.

The study was carried out by a team comprising, among others, Marc Postman, from the Space Telescope Science Institute (STScI), and Michael Shull, from the University of Colorado at Boulder, both institutions in the United States.

The study is based on observations made by NASA’s New Horizons spacecraft, which flew past Pluto in 2015 and continued moving away from the Sun and Earth, now nearly 9 billion kilometres from our planet.

The authors of the study set out to answer the deceptively simple question: Does total darkness reign in areas of space far enough away from stars?

Space in these regions may appear pitch black to human eyes, but it has always been suspected that it is not completely dark. Since the universe was formed, billions of galaxies containing numerous stars have formed, and even when they have died, their light has continued to travel through the universe, even if it is now very dim. This extremely weak glow that bathes the universe is called the cosmic optical background.

Based on the aforementioned observations by the New Horizons space probe, the authors of the study calculated how bright this cosmic optical background glow is.

An artist’s impression of the New Horizons spacecraft at the edge of the solar system. The Sun and a bright band representing zodiacal light, caused by sunlight reflecting off interplanetary dust, are visible in the background. (Illustration: Joe Olmsted/STScI)

The results of the calculations indicate that the cosmic optical background is approximately 100 billion times fainter than the sunlight reaching the Earth’s surface, too faint for humans to see with the naked eye.

In the future, more precise measurements of this cosmic optical background could help scientists confirm that there is nothing strange in it or, on the contrary, detect excesses of light that could reveal the existence of mysterious objects yet to be discovered that emitted their light into space.

The study is titled “New Synoptic Observations of the Cosmic Optical Background with New Horizons.” It has been published in the academic journal The Astrophysical Journal. (Source: NCYT by Amazings)