A ghostly glow of light surrounds the solar system and no one can explain it – ScienceAlert

A new analysis of Hubble data has confirmed it: there is too much light in space around the Solar System.

Not much extra light, for sure. Just a subtle, ghostly glow, a faint excess that cannot be counted in a census of all light-emitting objects.

All the stars and galaxies that surround the Solar System, and the zodiacal light, also known as the dust in the plane of the Solar System, none of them can explain what astronomers now call “ghost light.”

After analyzing 200,000 Hubble images and making thousands of measurements in a project called SKYSURFan international collaboration is sure that the excess light is real.

And besides, they can’t quite explain it. There are possibilities, but none of them have been confirmed. Not yet, anyway.

The strongest possibility? A dust component of the Solar System that we have yet to directly detect: tiny particles of dust and ice from a population of comets that travel inward from the dark regions of the Solar System, reflecting sunlight and generating a glow diffuse global

This source would be a little closer to us than the additional light detected by the New Horizons spacecraftwho found an excess of optical light in space beyond Pluto, outside the Solar System.

“If our analysis is correct, there is another component of dust between us and the distance where New Horizons made measurements. This means that this is some kind of extra light coming from the interior of our solar system “. says astronomer Tim Carleton from Arizona State University.

“Since our measurement of the residual light is higher than that of New Horizons, we believe that it is a local phenomenon that is not far outside the Solar System. It may be a new element for the contents of the Solar System that has been hypothesized but not quantitatively. measured so far.”

There are lots of very bright things floating around the Universe: planets, stars, galaxies, even gas and dust. And generally the shiny things are what we want to look at. Therefore, detecting ambient light in interstitial places (interplanetary, interstellar and intergalactic space) is a difficult thing to do.

However, when we look, sometimes we find that things are not as we expected.

For example, something we cannot explain in the galactic center is producing high energy light. Voyager I found an excess of brightness associated with hydrogen at the edge of the Solar System. There is the detection of New Horizons. Things are looking strangely bright out there.

The purpose of SKYSURF was to fully characterize the brightness of the sky.

“More than 95 percent of the photons in the Hubble archive images come from distances less than 3 billion miles from Earth. Since the early days of Hubble, most Hubble users have discarded these photons from the sky, since they are interested in the faint discrete objects in the Hubble images, such as stars and galaxies.” says astronomer and Hubble veteran Rogier Windhorst from Arizona State University.

“But these sky photons contain important information that can be extracted thanks to Hubble’s unique ability to measure faint brightness levels with high precision over its three-decade lifetime.”

Across three separate papers, the researchers scoured the Hubble archive for signs of faint galaxies we might have missed and quantified the light that should be emitted by objects that are known to glow.

The team that searched for hidden galaxies determined that not enough galaxies were missed to account for the extra light.

The resulting excess was, according to scientists, equivalent to a constant glow emitted by 10 fireflies across the sky.

This may not seem like much, but it is enough to know that we are missing something. And it is important. More and more, scientists are finding ways to see the light between the stars. If there is a local excess, we need to know about it, as it could distort our understanding of more distant ghostly glows.

And of course there’s the impact it could have on our understanding of the Solar System and how it holds together.

“When we look at the night sky, we can learn a lot about the Earth’s atmosphere. Hubble is in space.” says astronomer Rosalia O’Brien from Arizona State University.

“When we look at this night sky, we can learn a lot about what’s happening in our galaxy, our Solar System and on large scales like the entire Universe.”

All three published SKYSURF articles have been published on The Astronomical Magazine i The Astrophysical Journal Lettersand can be found here, herei here. A fourth work, sent to The Astronomical Magazine and yet to publish, can be found on the arXiv preprint server.