It's equivalent to the glow of 10 fireflies spread across the entire night sky.

hubble space telescope spots haunting glow surrounding the solar system
An illustration showing a hypothetical cloud of dust that could come from infalling comets. (Image credit: NASA, ESA, Andi James (STScI))

Did someone leave a light on?

The solar system is surrounded by an eerie ghostly glow that persists after all known light sources are accounted for, according to new research from the Hubble Space Telescope. The discovery suggests that models of the solar system’s structure may have to be revised. 

“It may be a new element to the contents of the solar system that has been hypothesized but not quantitatively measured until now,” Tim Carleton, an astronomer at Arizona State University and lead author of the research, said in a statement. 

The findings came about when astronomers attempted to answer the question, “How dark is dark?” As part of a project called SKYSURF, the team sorted through 200,000 images from the Hubble Space Telescope, systematically eliminating the glow from planets, stars, galaxies, and from dust in the plane of our solar system and making tens of thousands of measurements to detect the residual glow in the night sky after these sources were removed.

They found a tiny excess of light, equivalent to the glow of 10 fireflies spread across the entire sky. 

In a statement, NASA officials described this as being similar to walking into a room at night, turning out all the lights and closing the shades. Despite the darkening of the room, an eerie glow comes from the walls, ceiling and floor even after all light sources have been eliminated. 

While this might sound like a haunting scene facing a protagonist in a classic ghost tale, the eerie glow discovered around the solar system has a rational and definitely non-supernatural explanation. 

The team thinks that one possible explanation for this solar system glow is reflected sunlight from a sphere of dust left behind by comets that are falling into the solar system. The solar system’s background glow is smoothly distributed, which would match an origin with the innumerable snowballs of ice and dust that approach the sun from all directions. 

As comets approach, heat from the sun causes solid material within comets to instantly transform into gas, or sublimate, causing an exhaust of dust and ice to burst free from the cosmic snowballs; this exhaust could then reflect back sunlight to create the eerie glow.

Such a shell of dust would represent a new addition to what astronomers know about the architecture of the solar system. 

Cosmic ‘ghost hunting’ with Hubble and New Horizons 

This isn’t the first time astronomers have spotted a ghostly glow around the solar system. In 2021, NASA’s New Horizons spacecraft also aimed to measure the background glow of the sky. 

The probe had flown past Pluto in 2015 and is now heading out of our planetary system and into interstellar space, and it took measurements of the solar system at a distance of 4 billion to 5 billion miles (6.5 billion to 8 billion kilometers) from the sun.

New Horizons was beyond possible light contamination from planets and asteroids, but not yet affected by interplanetary dust, and it detected a faint background light that to this day remains unexplained, although one hypothesis is that it originates outside of the solar system when dark matter particles annihilate each other. 

However, the light source from this earlier investigation seemed to be farther out than the glow discovered recently by the SKYSURF team.

“If our analysis is correct, there’s another dust component between us and the distance where New Horizons made measurements,” Carleton said. “That means this is some kind of extra light coming from inside our solar system.”

The idea to use Hubble data to search the solar system for this ghostly light came from veteran astronomer Rogier Windhorst at the Arizona State University, who saw important information encoded in photons that astronomers usually ignored. 

“More than 95% of the photons in the images from Hubble’s archive come from distances less than 3 billion miles [4.8 billion km] from Earth,” Windhorst said. “Since Hubble’s very early days, most Hubble users have discarded these sky-photons, as they are interested in the faint discrete objects in Hubble’s images such as stars and galaxies.” 

The team’s research is published in two papers published in October and November in the Astronomical Journal and the Astrophysical Journal Letters. 

Follow us on Twitter @Spacedotcom or on Facebook.


Power on the Moon. What Will it Take to Survive the Lunar Night?

With the help of international and commercial partners, NASA is sending astronauts back to the Moon for the first time in over fifty years. In addition to sending crewed missions to the lunar surface, the long-term objective of the Artemis Program is to create the necessary infrastructure for a ...

View more: Power on the Moon. What Will it Take to Survive the Lunar Night?

Iwan Rhys Morus

Iwan Rhys Morus holds PhDs in the history and philosophy of science from the University of Cambridge. He has spent much of his career working on the history of science during the nineteenth century, including the development of new electrical technologies, the popular culture of science, and the history ...

View more: Iwan Rhys Morus

How do lie detectors work?

This article was first published on Big Think in October 2020. It was updated in December 2022. We all lie. Some might argue it’s human nature. In a 2002 study, 60% of people were found to lie at least once during a 10-minute conversation, with most people telling an ...

View more: How do lie detectors work?

How electricity stormed past steam and became the power of the future

Excerpted from HOW THE VICTORIANS TOOK US TO THE MOON, written by Dr. Iwan Rhys Morus and published by Pegasus Books. None of this happened by accident – and none of it happened as the result of acts of individual genius either. The business of electrification was a business, ...

View more: How electricity stormed past steam and became the power of the future

What is the true nature of our quantum reality?

When it comes to understanding the Universe, scientists have traditionally taken two approaches in tandem with one another. On the one hand, we perform experiments and make measurements and observations of what the results are; we obtain a suite of data. On the other hand, we construct theories and ...

View more: What is the true nature of our quantum reality?

Planetary Interiors in TRAPPIST-1 System Could be Affected by Solar Flares

In a recent study published in The Astrophysical Journal Letters, an international team of researchers led by the University of Cologne in Germany examined how solar flares erupted by the TRAPPIST-1 star could affect the interior heating of its orbiting exoplanets. This study holds the potential to help us ...

View more: Planetary Interiors in TRAPPIST-1 System Could be Affected by Solar Flares

SpaceX’s last Starlink launch of 2022 is a bit of a mystery

In a strange twist, SpaceX says that its next Starlink mission will launch 54 satellites into low Earth orbit (LEO), implying that they’re roughly the same size as the V1.5 satellites it’s already launching – not the larger V2 or V2 Mini satellites hinted in recent FCC filings. However, ...

View more: SpaceX’s last Starlink launch of 2022 is a bit of a mystery

Is Mining in Space Socially Acceptable?

Traditional mining has been subject to a negative stigma for some time. People, especially in developed countries, have a relatively negative view of this necessary economic activity. Primarily that is due to its environmental impacts – greenhouse gas emissions and habitat destruction are some of the effects that give ...

View more: Is Mining in Space Socially Acceptable?

“Mad honey”: The rare hallucinogen from the mountains of Nepal

Fred Hogge

The history of ice, one of the first luxuries

Astronomy 2023: Top Sky Watching Highlights for the Coming Year

Are humans wired for conflict? Charles Darwin vs. "Lord of the Flies" - Big Think

What was the biggest explosion in the Universe?

Canada takes boldest stance on electric vehicles yet

Despite the low air Pressure, Wind Turbines Might Actually Work on Mars

NASA Makes Asteroid Defense a Priority, Moving its NEO Surveyor Mission Into the Development Phase

Lightweight Picogram-Scale Probes Could be the Best way to Explore Other Star Systems

World’s biggest cultivated meat factory is being built in the U.S.

Ndidi Akahara


Top Car News Car News