The sun’s innermost planet has a very dusty mystery. Scientists just found a ring of dust more than 9 million miles wide sharing Mercury’s orbit, which they didn’t think was possible. It’s also not the only one.
Dust in the Wind
The solar system used to be just gas and dust, and then over time, little nodules of the stuff collected and grew under their neighbors’ gravity. From dust particles and gas blobs grew asteroids and comets, then small planets, and then — where enough material was available — very large worlds.
Scientists stumbled across the dust ring while building a model based on pictures from NASA’s Solar and Terrestrial Relations Observatory spacecraft, or STEREO. Their goal was to help a newer satellite, the Parker Solar Probe, take better images of dust near the sun.
This ring was a huge surprise. Scientists thought that the constant stream of charged particles from the sun known as the solar wind, along with the sun’s magnetic forces, would push the dust far beyond Mercury’s orbit. But it looks like tiny Mercury was just big enough for its gravity to capture this dust and hold it in place.
The research was published in The Astrophysical Journal in November 2018and highlighted on NASA’s website this week. The lead author was Guillermo Stenborg, also of the Naval Research Laboratory and currently located at the University of Colorado.
Asteroids Near Venus
While scientists work on the dusty Mercury mystery, they also found that asteroids crossing the orbit of Venus may have created a similar dusty ring near Venus. Venus is the second planet out from the sun and is roughly the same size as Earth, although it has a hellish surface full of high temperatures, possibly active volcanoes, and extremely high pressure. No spacecraft has survived there for long.
