On 16 November 1974, the Arecibo radio telescope beamed a 1,679-bit message towards the star cluster M13: numbers, DNA, a human figure, the Solar System. Because 1,679 is the product of two primes, it can be rearranged into a picture. But the cluster is about 25,000 light-years away and will have moved by then. It was above all a symbolic gesture.
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.