Hubble detects a ghostly glow surrounding our solar system

It is hypothesized that this glow may be caused by sunlight reflecting off cometary dust in the solar system . 


It is small, equivalent to the constant brightness of 10 fireflies spread across the entire sky.

Tens of thousands of measurements on 200,000 archival images from the Hubble telescope have revealed a faint ghostly glow surrounding our solar system .

Aside from a tapestry of sparkling stars and the glow of the waxing and waning moon, the night sky looks inky black to the casual observer. But how black is the night sky really?

To find out, astronomers searched for any residual background glow in the sky, in an ambitious project called SKYSURF . This would be any light left over after subtracting the brightness of planets, stars, galaxies, and dust in the plane of our solar system (called zodiacal light).

When the researchers completed this inventory, they found an extremely small excess of light, equivalent to the constant brightness of 10 fireflies spread across the entire sky. That’s like turning off all the lights in a closed room and still finding a ghostly glow coming from the walls, ceiling, and floor.

What is this glow that surrounds the solar system due to?

The researchers say that one possible explanation for this residual glow is that our inner solar system contains a faint sphere of dust from comets falling into the solar system from all directions, and that the glow is sunlight reflecting off this dust. If real, this layer of dust could be a new addition to the known architecture of the solar system .

This idea is reinforced by the fact that in 2021 another team of astronomers used data from NASA’s New Horizons spacecraft to also measure the sky background. New Horizons flew past Pluto in 2015 and a small Kuiper belt object in 2018, and is now heading into interstellar space. The New Horizons measurements were made at a distance of 6 to 7.5 billion kilometers from the sun. This is outside the realm of planets and asteroids where there is no contamination by interplanetary dust.

New Horizons detected something slightly fainter apparently coming from a more distant source than Hubble detected . The source of the backlight seen by New Horizons also remains unexplained. There are numerous theories ranging from the decay of dark matter to a huge invisible population of remote galaxies.

“If our analysis is correct, there is another component of dust between us and the distance where New Horizons made the measurements. That means it’s some kind of extra light coming from inside our solar system,” said Tim Carleton of the University State of Arizona (ASU), in a statement.

“Because our residual light measurement is higher than New Horizons’, we believe it is a local phenomenon not too far from the solar system . It may be a new element of solar system content that has been hypothesized.” , but not measured quantitatively until now,” Carleton said.

Veteran Hubble astronomer Rogier Windhorst, also of ASU, first had the idea of ​​pooling the Hubble data to look for any “ghost lights.”

“More than 95% of the photons in the images in the Hubble archive come from distances less than 3 billion miles from Earth. Since the early days of Hubble , most Hubble users have dismissed these photons from the sky, since who are interested in the faint discrete objects in the Hubble images , such as stars and galaxies,” Windhorst said.

“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,” he added. (Europe Press)