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Is space really black? Astronomer Todd Lauer has been wondering for some time. If I could see the night sky without stars, galaxies and the rest of the known visible light sources, would we be in absolute black?
The surprise is that it isn’t. Lauer and other researchers from NASA’s New Horizons mission used this spacecraft’s telescope and camera and discovered something curious that they can’t explain very well: the universe isn’t as black as it is painted.
The space is “dark enough”
New Horizons had the original mission of studying Pluto, but it already passed the dwarf planet in 2015 and did its job, and now it has simply continued its journey and is currently about 7.4 billion kilometers from Earth.
This means that this spacecraft is now far from any source of light pollution that could prevent it from detecting light signals from the universe itself.
As these astronomers explained, both around our planet and in the inner solar system, space is filled with dust particles that are illuminated by the Sun and which create a diffuse glow throughout the sky, but the light that comes from the sun it’s much fainter where New Horizons is now.
To try to answer this initial question, the astronomers used the spacecraft’s instruments to analyze the surrounding outer space. They selected images that qualify as an empty sky, where there are some small lights from distant but very faint stars and galaxies.
They processed those images to eliminate all visible light sources. After eliminating the light that comes from the stars and the light that comes from the Milky Way they also eliminated any stray light from the peculiarities of the camera. The theoretical result was to be left alone with the light that came from beyond our galaxy.
Even then they weren’t satisfied: they went further and subtracted the light that could be attributed to galaxies that could have been captured by those cameras. Even doing all of this, there was still light in an image that wasn’t completely black when it should be.
Pluto and Charon, seen from New Horizons. Photo: JHUAPL / SwRI. In fact, Marc Postman, one of the astronomers involved in the study, pointed out that the amount of light from unknown sources was equivalent to that from known galaxies. This has left scientists perplexed, who believe there are unknown galaxies out there “or another light source we don’t yet know about.”
Preliminary studies that have also been done with the New Horizons probe have pointed in that direction without being so precise. There is no definitive explanation for a phenomenon that is surprising to experts and which could also be associated with dark matter.
For Lauer, as for other astronomers, the discovery is disturbing, but he ended up saying that even after all these analyzes “space is dark enough”.
Street | NPR
More information | arXiv
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