The true darkness of the universe is a challenge. Earth’s atmosphere emits a faint glow even on the darkest night due to ultraviolet light from the Sun and cosmic rays interacting with the upper atmosphere. Even in the most advanced observatories, atmospheric light pollution limits the view of ground-based telescopes.
as you remember Science AlertTelescopes like Hubble and James Webb get the purest views of the sky from beyond Earth’s atmosphere. However, these telescopes still do not capture the truly dark sky.
Diffuse dust in our Solar System scatters light, and each particle contributes to a glow known as a sunglow. Even in interplanetary space, the night is not completely dark.
The solution? The New Horizons
To experience cosmic darkness at its best, it would be necessary to travel beyond the dust and reach the outer edge of our Solar System, beyond Pluto. Ships like Voyager I and II have reached this region, and NASA’s New Horizons spacecraft has also ventured beyond.
New Horizons, after exploring Pluto and the Kuiper belt, is now twice as far from the Sun. Recently, the mission team looked at a corner of the sky away from the Milky Way and the glare of the Sun, to measure how much light the camera was capturing.
They compared these data with those from the Hubble Space Telescope and discovered an unexpected, mysterious faint glow that has astronomers intrigued.
Despite being in a region of space where little backlight is expected, the brightness measured by New Horizons turned out to be about double. To solve this puzzle, the team plans to observe more dark areas in the next month, seeking to better understand the sheer darkness of the cosmos or to tease out the cause of this unexpected glow.