A cool closeup of a comet. The bright dots that […]

A cool closeup of a comet.

The bright dots that look like falling snow are actually background stars. The more rapidly moving streaks are probably dust particles illuminated by the Sun, sprinkled with a few streaking cosmic rays.

Comets offer a window to 4.6 billion years ago. As Rosetta helped establish, they are orbiting remnants from when our Solar System formed, rather than fragments from later collisions.

From the European Space Agency’s Rosetta spacecraft circling Comet 67P/Churyumov–Gerasimenko, and assembled by a cool cat: https://twitter.com/landru79