The Sun's surface constantly rises and falls in oscillations of about five minutes, driven by sound waves resonating inside the star. By measuring millions of these vibrations, astronomers practice helioseismology, just as geologists probe Earth's interior using earthquakes. That is how we know what lies inside a star nobody can ever drill into.
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.