Triton is the only large moon in the Solar System that orbits in the opposite direction to its planet's spin. Such an orbit can hardly form in place, so Triton is probably a former Kuiper Belt object, a cousin of Pluto, captured by Neptune. In 1989, Voyager 2 even photographed nitrogen geysers erupting on its surface.
A large share of Earth's water molecules formed in the interstellar cloud that existed before the Sun was even born, more than 4.6 billion years ago. You are literally drinking a cosmic fossil.
By day, the Martian sky looks butterscotch because of fine dust hanging in the air. But at dusk, those same grains scatter blue light forward, creating a bluish glow around the Sun. Rovers have photographed these blue sunsets: the exact reverse of what we see on Earth.