Mercury, the closest planet to the sun, is sharing its orbit with a vast ring of fine cosmic dust that has never been observed before.

Guillermo Stenborg and Russell Howard, a pair of solar scientists from the Naval Research Laboratory, found evidence of the existence of a 9.3 million mile-wide dust ring around the sun located in the orbit of Mercury using data from NASA's STEREO (Solar and Terrestrial Relations Observatory).

Their findings were published in The Astrophysical Journal on Nov. 21, 2018.

Mercury's Dusty Orbit

The two scientists discovered the new dust ring within the inner solar system while searching for a dust-free region near the sun. Previous models predicted that at some point, the extreme heat from the yellow dwarf would immediately vaporize cosmic dust, leaving a clean stretch of space.

However, searching for the theoretical dust-free region around the sun has been a challenge. All the dust floating between the Earth and the sun is obstructing the view of scientists.

Stenborg and Howard found a way around the problem by creating a new model based on the photos of interplanetary space from STEREO. When they tested the new model, two lights showed up: one from the sun's corona and the sunlight reflecting from cosmic dust.

The scientists wanted to devise a technique to separate the light coming from the corona and the light reflected by the dust. Removing the light from the corona would reveal the dust-free space they have been searching for.

They found the dust ring in the orbit of Mercury while working on the new model and their technique. Looking at the STEREO images, they noticed a pattern of enhanced brightness along the area.

"It wasn't an isolated thing," explained Howard. "All around the Sun, regardless of the spacecraft's position, we could see the same five percent increase in dust brightness, or density. That said something was there, and it's something that extends all around the Sun."

The Story Of The Formation Of The Solar System

Scientists believe that finding the boundary where the heat of the sun would vaporize cosmic dust would reveal their composition. Dust is a remainder from asteroid collisions and blazing comets.

However, dust is also remnants from the early history of the solar system. Scientists believe that cosmic dust is the raw material from which planets are formed. The study of cosmic dust could reveal how planets, including Earth, formed billions of years ago.

Stenborg and Howard will continue to look for the dust-free region around the sun. The solar scientists are hoping to use their new model and technique on the data beamed back by the Parker Solar Probe that continues to explore the corona of the yellow dwarf in the heart of the solar system.

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