A Ghostly Glow of Light Surrounds the Solar System and No One Can Explain It

A new analysis of the Hubble data has confirmed it: there is plenty of light in the space around the Solar System. Not much extra light, that’s for sure. Just a subtle, ghostly glow, a slight 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 dust in the plane of the Solar System, none of that can explain what astronomers call “ghost light.”

After analyzing 200,000 Hubble images and taking thousands of measurements in a project called SKYSURF, an international collaboration ensures that the excess light is real.

And besides, they can’t explain it. There are possibilities, but none of them have been confirmed. Not yet, anyway. The strongest possibility? A component of Solar System dust that we have not yet directly detected: tiny particles of dust and ice from a population of comets that travel into the dark regions of the Solar System, reflecting sunlight and generating a diffuse global glow. This source would be slightly closer to us than the extra light detected by the New Horizons space probe, which found an excess of optical light in space beyond Pluto, outside the Solar System.

“If our analysis is correct, there is another dust component between us and the distance where New Horizons took the measurements. This means it’s some kind of extra light coming from our Solar System,” he said. says astronomer Tim Carleton of Arizona State University. “As our residual light measurement is higher than New Horizons, we think it is a local phenomenon that is not very far from the Solar System. It may be a new element for the content of the Solar System that was hypothesized, but not quantitatively. measured so far.”

There are lots of really bright things floating around in the Universe: planets, stars, galaxies, even gas and dust. And generally, the shiny things are the things we want to see. Therefore, detecting ambient light in interstitial locations (interplanetary, interstellar, and intergalactic space) is somewhat tricky. However, when we look, sometimes we find that things are not as we expected. For example, something we can’t explain at the galactic center is producing high-energy light Voyager I found excess brightness associated with hydrogen at the edge of the Solar System There’s the detection of New Horizons. Things are looking strangely bright out there.

SKYSURF’s goal was to fully characterize the brightness of the sky. “More than 95 percent of the photons in the archive Hubble images come from distances of less than 3 billion miles from Earth. Since the early days of Hubble, most Hubble users have dismissed these photons from the sky because they are interested in faint discrete objects in Hubble. images, like stars and galaxies,” says astronomer and Hubble veteran Rogier Windhorst of Arizona State University.

“But these photons from the sky contain important information that can be gleaned thanks to Hubble’s unique ability to measure faint brightness levels with high precision over its three decades of life.”

In three separate papers, the researchers scoured the Hubble archive for faint signals from galaxies that we might have missed, and quantified the light that objects known to shine should be emitting.