Astronomy is the study of outer space and the entire physical universe. Prepare your mind for lift off with these out-of-this-world space facts about planets, stars, asteroids, galaxies and more.
Although they can't take off their suits and helmets while on a spacewalk (well, they could, but it probably wouldn't go too well), astronauts often get a whiff of a distinct odor after returning to their spacecraft.
After his mission in 2003, astronaut Don Pettit said that, although the scent is hard to describe, it vaguely reminded him of when he used to work with an arc welder, repairing logging equipment. Other astronauts have described the smell as similar to burning steak, ozone, walnuts, brake pads, and even burnt almond cookie.
A micrometeorite is an extra-terrestrial dust particle, measuring from about 50 nm (nanometers, or millionths of a meter) to 2 mm, that has survived entry through the Earth's atmosphere. Astronomers believe that more than 3,000 micrometeorites fall to Earth every second.
Think the Milky Way is big? The universe is made up of over 50 billion galaxies. In fact, there are more than one sextillion stars in space—that's 1,000,000,000,000,000,000,000.