Hubble Detects Mysterious Ghostly Glow Surrounding Our Solar System 

This artist’s illustration shows the location and size of a hypothetical cloud of dust surrounding our solar system. Credit: NASA, ESA, Andi James (STScI)

Exhaust from Infalling Comets Makes Space a Dusty Place

Imagine walking into a room at night, turning off all the lights, and closing the shades. Yet an eerie glow comes from the walls, ceiling, and floor. The faint light is barely enough to see your hands before your face, but it persists.

Sounds like a scene out of “Ghost Hunters?” No, for astronomers this is the real deal. However, looking for something that’s close to nothing is not easy. Astronomers searched through 200,000 archival images from Hubble Space Telescope and made tens of thousands of measurements on these images to look for any residual background glow in the sky. Like turning out the lights in a room, they subtracted the light from stars, galaxies, planets, and even the zodiacal light. (Zodiacal light is a faint glow of diffuse sunlight scattered by interplanetary dust.) Surprisingly, a ghostly, feeble glow was left over. It’s equivalent to the steady light of ten fireflies spread across the entire sky.

Where’s that coming from?

One possible explanation is that a shell of dust envelops our solar system all the way out to

This artist’s illustration shows the location and size of a hypothetical cloud of dust surrounding our solar system. Astronomers searched through 200,000 images and made tens of thousands of measurements from Hubble Space Telescope to discover a residual background glow in the sky. Because the glow is so smoothly distributed, the likely source is innumerable comets – free-flying dusty snowballs of ice. They fall in toward the Sun from all different directions, spewing out an exhaust of dust as the ices sublimate due to heat from the Sun. If real, this would be a newly discovered architectural element of the solar system. Credit: NASA, ESA, Andi James (STScI)