Space facts

After watching the 6-part series from the BBC called "The Cosmos" last week, I went fishing for facts to feed my revigourated hunger. I'll put a few here:

• The distance from the surface of Earth to the centre is about 3,963 miles. Because much of Earth is fluid, the solid skin of the planet is only 41 miles thick - thinner than the skin of an apple, relatively speaking.
• You could fit approximately 1,000,000 Earths inside the Sun.
• The surface area of the Earth is 196,950,711 square miles.
• Our Solar System is moving at 43,000mph through our galaxy - the Milky Way.
• Some of the objects visible in Hubble Space Telescope images are nearly 4,000,000,000 (billion) times fainter than the limits of human vision.
• If you suspend three grains of sand in a large sports arena, such as Madison Square Garden in New York, the arena will be more closely packed with sand than our galaxy is with stars.
• The Earth orbits the Sun at an average velocity of approximately 18 miles per second.
• Due to frequent collisions with subatomic particles, it takes a typical gamma ray photon about one million years to travel from the core of the Sun to its surface, even though gamma rays travel at the speed of light (the gamma ray region of light has shorter wavelengths than X-rays). By the time the photon that started out as a gamma ray photon escapes the solar furnace, it has lost so much energy through collisions that it emerges from the Sun's surface as a photon of ordinary, visible light.
• And, one of my favourites(!) - there are more stars in our universe than there are grains of sand on the whole of Earth..