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How dark is space? Astronomers who tried to answer the question found a surprising answer: not as dark as they thought.
Researchers using images from NASA’s distant New Horizons space probe have found a very faint glow of visible light invading the universe.
Astronomer Tod Lauer, of the National Science Foundation’s National Optical-Infrared Astronomy Research Laboratory (NOIRLab), examined images taken by the probe as it peered beyond our galaxy. He and his colleagues were especially looking for fields of view that did not include stars and galaxies so that they could measure how dark space was.
“What we found when we were done is a bit lighter than what we thought was or should be there,” he said. Quirks & Quarks host Bob McDonald.
“There is a very faint, very faint glow, but it’s more than we can explain from known sources,” such as local stars, distant galaxies, or interstellar dust, he said.
“So it’s a small component of the universe that we have discovered.”
A shining mystery
In an attempt to figure out the source of the faint glow, Lauer and her colleagues systematically eliminated all sources of light that it could possibly be. The New Horizons images, to date, are the only ones that could be useful in this study, which was accepted for publication in The Astrophysical Journal.
After the New Horizons flyby of Pluto in the summer of 2015, it continued to traverse the far reaches of our solar system and is currently on the edge of the Kuiper Belt and on the verge of leaving the solar system, making it only the fifth artificial craft to do it.
In the inner solar system, space is filled with dust particles that reflect sunlight, which produces a diffuse glow in images taken by ground or orbital telescopes.
But beyond Pluto, where New Horizons currently sails, it’s beyond the light “pollution” caused by sunlight bouncing off dust and debris in our solar system. He is able to see the darkness of space clearly in the same way we might see the night stars more clearly when we leave a city and go out into the countryside.
The team combed through the archive of images from the New Horizons mission and subtracted all known light sources, including stars in the Milky Way and galaxies far away.
They also had to eliminate any light that could be coming from the spacecraft itself, any camera flaws, and possible errors in their calculations.
WATCH | The New Horizons journey is lively. (NASA)
https://www.youtube.com/watch?v=/78U0_XcFP_I
The mysterious diffuse glow remained.
So far, the team has no good explanation for the source of this light, and they are left with some speculation. One possibility is that rogue stars in intergalactic space are too dark to be considered points of light, Lauer said.
“Maybe there are stars that have been plucked from galaxies as they emerge and interact with each other to form a diffuse background.”
“There are a few more wacky suggestions,” Lauer said. One concerned the interactions between still hypothetical particles of exotic “dark matter” thought to be present throughout the universe.
“Some people thought that there might be particles that interact and sometimes annihilate each other and that could produce light. It’s more speculative.”
Lauer even revisited a previously dismissed theory – one that astronomers don’t want to be true.
“New Horizons has an instrument to look for dust by simple direct impact, and we don’t see much. So we think it’s clean there,” he said. “But maybe we’re wrong and maybe there is a cloud of dust scattering sunlight even far into the Kuiper Belt.”
How bright is this faint glow?
Lauer says that this diffused glow represents a significant amount of light – roughly the same amount of light we see in galaxies across the universe. It’s just very widespread in the vastness of space.
It’s also not very interesting to watch in the footage captured by New Horizons.
“It sounds like noise,” Lauer said. “It’s about as exciting as watching a blank picture on the TV. It’s just static.”
To give an idea of how dim this glow is, Lauer gave an analogy.
“Imagine you are in the countryside and it is a moonless night,” he said. “You have a neighbor a mile down the road and the neighbor walks into his kitchen at 3 a.m. and opens the refrigerator door. Getting that much light a mile away is roughly equivalent to what we see from there. distant universe. “
While astronomers don’t have a satisfactory explanation for this light, finding a new phenomenon like this – a new puzzle to solve – is certainly rewarding in itself.
“If we didn’t have our mysteries, we would have to find something else to do. One of my pleasures of being an astronomer is that you can ask questions like, ‘How dark is space? “”
“There will always be mysteries, I hope.”
Written and produced by Mark Crawley
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