Our Solar System Francine Campogni How Big is Big? Planet Size The “nine” planets How Big is the Sun? The Milky Way • Our solar system may seem big to us. But it is only a tiny part of a huge galaxy - the Milky Way. The Milky Way Galaxy is a tiny part of the universe. Click on galaxy The Milky Way is made of… • Gas • Dust • Stars (over 200 billion in the Milky Way alone!) • So far, astronomers have found about 70 solar systems and are discovering new ones every year. Given how many they have found in this neighborhood of the Milky Way galaxy, scientists estimate that there may be many billions of solar systems in our galaxy. The Sun The Sun is personified in many mythologies: the Greeks called it Helios and the Romans called it Sol. Click on our star Mercury In Roman mythology Mercury is the god of commerce, travel and thievery, the Roman counterpart of the Greek god Hermes, the messenger of the Gods. The planet probably received this name because it moves so quickly across the sky. Click on the inner planet Venus Venus (Greek: Aphrodite; Babylonian: Ishtar) is the goddess of love and beauty. The planet is so named probably because it is the brightest of the planets known to the ancients. (With a few exceptions, the surface features on Venus are named for female figures.) Click on the inner planet Earth Earth is the only planet whose English name does not derive from Greek/Roman mythology. The name derives from Old English and Germanic. There are, of course, hundreds of other names for the planet in other languages. In Roman Mythology, the goddess of the Earth was Tellus - the fertile soil (Greek: Gaia, terra mater - Mother Earth). Click on our home planet The Moon Called Luna by the Romans, Selene and Artemis by the Greeks, and many other names in other mythologies. Click on Earth’s satellite Mars Mars (Greek: Ares) is the god of War. The planet probably got this name due to its red color; Mars is sometimes referred to as the Red Planet. (An interesting side note: the Roman god Mars was a god of agriculture before becoming associated with the Greek Ares; those in favor of colonizing and terraforming Mars may prefer this symbolism.) The name of the month March derives from Mars. Click on the inner planet Asteroids 1801 Year Giuseppe Piazzi discovered the first asteroid, Ceres. Click on the rocky orbiter Jupiter • Jupiter (a.k.a. Jove; Greek Zeus) was the King of the Gods, the ruler of Olympus and the patron of the Roman state. Zeus was the son of Cronus (Saturn). Click on the outer planet Saturn Click on the outer planet In Roman mythology, Saturn is the god of agriculture. The associated Greek god, Cronus, was the son of Uranus and Gaia and the father of Zeus (Jupiter). Saturn is the root of the English word "Saturday" Uranus Uranus is the ancient Greek deity of the Heavens, the earliest supreme god. Uranus was the son and mate of Gaia the father of Cronus (Saturn) and of the Cyclopes and Titans (predecessors of the Olympian gods). Click on the outer planet Neptune In Roman mythology Neptune (Greek: Poseidon) was the god of the Sea. Click on the outer planet Comets Comets occasionally appear in our night skies. We see them as bright—or faint—fuzzy balls of light, with one or two long tails streaming out. They look nothing like stars, the moon, or any other object we see in the sky. That is because they really are quite different! The comets we see, and the trillions more we don’t, are part of our own solar system. It is mostly the force of our Sun’s gravity that influences their Click on the icy “stuff” orbits. Comets are actually icy, leftover chunks of the stuff that formed our solar system four and one-half billion years ago. Historical Images Click on the picture below to view some historical images from NASA. Watch video straight from NASA!