Space dust consists of crushed-up remains from the formation of the solar system and includes rubble from asteroid collisions or pieces of comets.
When dust in space settles, it often forms grainy rings overlying the orbits of Earth and Venus. Scientists sift through this space dust and study it in order to better understand it and also to find clues about the birth of the solar system itself.
Now, two recent NASA studies have revealed some fascinating new findings, including never-before-detected asteroids.
While previous research has shown that the dust ring in Earth’s orbit comes largely from the asteroid belt due to the planet’s gravitational pull, astrophysicist Petr Pokorny found that this was not the case for the dust ring in Venus’s orbit. This led to Pokorny and his research partner, Marc Kuchner, wondering about the mysterious origins of the dust ring.
After a series of simulations, the researchers hypothesised that it comes from a group of never-before-detected asteroids orbiting the sun alongside Venus.
Kuchner said the most exciting thing about this result is that “it suggests a new population of asteroids that probably holds clues to how the solar system formed”.
Pokorny modelled all the dust sources he could think of using a dozen different modelling tools, looking for a simulated Venus ring that matched the observations.
The researchers deduced there could be a group of asteroids co-orbiting the sun with Venus, meaning they share Venus’s orbit, but stay far away from the planet, often on the other side of the sun.
Using this information, the researchers modelled many potential versions of it. Of all the possibilities, one group alone produced a realistic simulation of the Venus dust ring: a pack of asteroids occupying Venus’s orbit and matching its trips around the sun one for one.
Pokorny said they were excited by their discovery but then realised there was still a lot more work to do to. “We thought we’d discovered this population of asteroids, but then had to prove it and show it works.”
To show the existence of their test asteroids, the researchers built another simulation, starting with multitude of 10,000 asteroids neighbouring Venus. They let the simulation run through 4.5bn years of solar system history, incorporating all the gravitational effects from each of the planets. When the simulation arrived at present day, approximately 800 of the scientists’ test asteroids had survived. Their work was published in The Astrophysical Journal Letters.
Their results indicate that asteroids could have formed near Venus’s orbit in the chaos of the early solar system, and some could still be there today, feeding the dust ring nearby.
Pokorny’s next step is to locate the mysterious asteroids. “If there’s something there, we should be able to find it.”
A new dust ring discovery
Another recent NASA study has uncovered a new dust ring around the sun.
Solar scientists Guillermo Stenborg and Russell Howard found the new dust ring by chance, stumbling upon it while searching for evidence of a dust-free region close to the sun.
During their search, the scientists noticed a pattern of enhanced brightness along Mercury’s orbit, which was more dust in the light that they had otherwise planned to discard. They describe evidence of a fine haze of cosmic dust over Mercury’s orbit, forming a ring 9.3m miles wide.
Howard said the findings weren’t an isolated occurrence. “All around the sun, regardless of the spacecraft’s position, we could see the same 5pc increase in dust brightness, or density. That said something was there, and it’s something that extends all around the sun,” he said.
Stenborg deduced that the dust ring probably went undetected for so long because scientists had previously never considered that a ring might exist along Mercury’s orbit.
“People thought that Mercury, unlike Earth or Venus, [was] too small and too close to the sun to capture a dust ring,” he said. “They expected that the solar wind and magnetic forces from the sun would blow any excess dust at Mercury’s orbit away.”
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