Dust arises everywhere – on bookshelves under the sofa, and now apparently in rings around mercury. Astronomers have made a surprising discovery and found a ring of cosmic dust in an unexpected place in our solar system.
Solar scientists Guillermo Stenborg and Russell Howard of the Naval Research Laboratory in Washington, D.C. did not appear to seek dust. On the contrary – they were looking for a dust-free region close to the Sun in preparation for the exploration by Parker Solar Probe. Scientists believe that there should be a region close to the sun where the heat of the star would evaporate dust, and finding the edge of this region would tell us more about what cosmic dust is made of and how planets are formed in a young solar system.
Instead, Stenborg and Howard stumbled upon a "cosmetic dust" that sprinkled over the Mercury orbit, forming a ring that is 9.3 million miles wide. Mercury itself is only 3,030 miles wide, so it flows through a huge sea of dust as it moves around the sun.
"We're not really dusty people," Howard said in a statement. His team tried to remove the effects of the dust from pictures, so Parker Solar Probe can see the sun more clearly. "The dust near the sun only appears in our observations, and generally we have thrown it away." But this time, they realized that the dust they were trying to scrub off was much closer and more widespread than they expected.
It was not the previous researchers that there could be a dust ring around mercury, so no one had to think about looking for one before. "People thought that mercury, unlike Earth or Venus, is too small and too close to the sun to capture a dust ring," Stenborg said. "They expected that solar wind and magnetic forces from the Sun would blow off excess dust in Mercury's circuit."
Now, Howard and Stenborg will face the challenge of examining Mercury's dust dust for "dust people" and will focus on searching for the dust-free zone as Parker Solar Probe explores the solar corona.