A is a ‘dirty snowball†of ice and rocky debris, typically a few miles across, that orbits the Sun in a long ellipse. When close to the Sun, the warmth evaporates the ice in the nucleus to form a coma (cloud of gas) and a tail. Named for their discoverers, comets sometimes make return visits after as little as a few years or as long as tens of thousands of years.
China set to retrieve Martian soil samples by 2030
China set to retrieve Martian soil samples by 2030 by Simon Mansfield Sydney, Australia (SPX) Apr 26, 2024 China is...