As it ages, the Sun keeps getting brighter. At its birth it shone about 30% more weakly, and four billion years ago it was still about a quarter dimmer, enough that Earth should have been frozen solid. Yet rocks from that time show signs of liquid water. This is the faint young Sun paradox, and a stronger greenhouse effect is the leading explanation.
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.