It’s National Astronomy Day! To celebrate, I thought I’d share some of the most interesting astronomy facts I’ve stumbled on while researching articles for this site. They’ve inspired me to keep studying, and maybe they’ll inspire other readers to start.

Fun Astronomy Facts:

Humans have watched the skies since ancient times, engaging in an early form of astronomy since at least 2000 B.C.E. The earliest astronomers came from Babylon, China, Greece, Italy, India, and Egypt, and observed the skies solely with the naked eye.

Astronomers thought our solar system was the center of the universe until 1918, when American astronomer Harlow Shapley determined this was false by studying the distribution of star clusters. The existence of other galaxies was not proved until 1924, when American astronomer Edwin Powell Hubble identified the Andromeda galaxy, and others, with the aid of a powerful 100-inch telescope.

A star begins as a cloud of dust and gas, which condenses to form a single star, a two-star system also known as a binary star, or a star cluster.

The first telescope was built in the early 1600s, by Dutch lens-grinder Hans Lipperhey.

The first asteroid to be discovered was Ceres, in 1801. It is believed there are millions of asteroids in our solar system, but only about 264,000 have been identified, and only about 12,136 of those have been named.

A comet looks like a dirty snowball until it approaches the Sun--a comet’s nucleus only shines when reflecting the Sun’s light, and the comet’s head and tail don’t form until the Sun’s heat causes dust and gas to evaporate.

According to some estimates, approximately 19,000 meteorites weighing about 3.5 ounces each shower the Earth every day, but only about 10 are recovered each year.

The first solar flares were recorded on Sept. 1, 1859, by scientists Richard C. Carrington and Richard Hodgson.

The Sun is the largest object in the solar system, and constitutes over 99 percent of the solar system’s mass.

A star’s color depends on its temperature: blue stars have the highest temperatures, followed by yellow-white stars, and finally by red stars, which have the coolest temperatures.