The Rosetta spacecraft spent two years around comet 67P, sniffing the gases streaming off it. The chemists' verdict: a bouquet of rotten eggs (hydrogen sulphide), horse stable (ammonia), bitter almonds (hydrogen cyanide) and alcohol. Not exactly inviting, but packed with molecules that fascinate origin-of-life researchers.
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.