The planet Mercury is being pelted regularly by bits of dust from an ancient comet, a new study has concluded. Comet Encke has the shortest period of any comet, returning to perihelion every 3.3 years. The dust from the comet affects Mercury’s tenuous atmosphere and may lead to a new understanding on how these airless bodies maintain their ethereal envelopes.
We can’t see the wind, but we can learn about it by observing things that are being blown about. And by studying changes in a comet’s bright tail of gas and ions, scientists are on the trail to solving two big mysteries about the solar wind — the supersonic outflow of electrically charged gas from the Sun’s million-degree upper atmosphere, or corona.