Planets and Galaxies

C. Observing the Solar System Geocentric- Earth at center with all other planets and sun orbiting it. Ptolemy- Greek astronomer developed the idea

2. Heliocentric- sun at center and all planets orbit it. Copernicus- Polish astronomer developed idea Galileo supported idea

Kepler 17th century German astronomer who discovered that the planets move in elliptical orbits around the sun.

Formation of the planets Protoplanet hypothesis suggests that the planets formed about 5 billion years ago in a great cloud of gas and dust rotated slowly in space. The cloud was at least 10 billion kilometers in diameter. As time passed, the cloud shrank under the pull of its own gravitation and formed the planets of our solar system.

Inner Planets Outer Planets Terrestrial Planets Mercury, Venus , Earth and Mars. Jovian, gaseous or Jupiter like planets Jupiter, Saturn, Uranus and Neptune

Terrestrial and Jovian Planets Why?

Nine Planets Mars Jupiter Uranus Pluto Mercury Neptune Saturn Earth Venus

Mercury One rotation takes 59 days. One year is 88 days. It has no moon or rings. Mercury is the closest planet to the sun. It looks a lot like our moon. Click here to learn about Mercury.

Venus One rotation takes 243 days. One year is 224.7 days. It has no moon or rings. Venus is the second planet from the sun. It is as dry as a desert and hotter than an oven.. Click here to learn more about Venus.

Earth One rotation takes 24 hours. One year is 365 1/4 days. It has 1 moon and no rings. It is the third planet from the sun. Earth is mostly covered with water. Click here to learn more about Earth

MARS One rotation takes 24.5 hours. One year is 687 days. It has 2 moons and no rings. It is the fourth planet from the sun and the last of the inner planets. Mars looks red because of rusty iron in its soil and red dust in its air. Click here to learn more about Mars

Jupiter One rotation takes 9.8 hours. One year is 12 earth years. It has at least 16 moons and 2 rings. It is the fifth planet from the sun and the first gas planet. It has a great red spot of swirling gas. Click here to learn more about Jupiter

Saturn One rotation takes 10.7 hours. One year is 29.5 Earth years. It has at least 17 moons and many rings. Saturn is the sixth planet from the sun and the second gas planet. Saturn’s rings are made of ice, rock, and dust. Click here to learn more about Saturn

Uranus One rotation takes 17 hours. One year is 84 earth years. It has at least 15 moons and 10 rings. Uranus is the seventh planet from the sun and the third gas planet. Uranus seems to rotate on its side. Click here to learn more about Uranus

Neptune One rotation takes 16 hours. One year is 165 earth years. It has 8 moons and 4 rings. It is the eighth planet from the sun and the last gas planet. Neptune is blue-green. Neptune Click here to learn more about Neptune

Pluto Recently reclassified as a dwarf planet One rotation takes 6 days. One year is 248 earth years. It has 1 moon and no rings. It is the ninth, and last planet from the sun, but every 248 years Neptune orbits farther than Pluto. Charon is Pluto’s moon. Click here to learn more about Pluto

Galaxies A system of clustered stars that slowly spin in space. Telescopes show that space contains at least several billion galaxies. Our solar system formed from a giant cloud of dust and gas and is in the Milky Way Galaxy. The Milky Way belongs to a small cluster of 17 galaxies called the LOCAL GROUP. Galaxies

Types of Galaxies There are three main types of galaxies. Spiral – have a central lens shaped bright nucleus made of millions of stars. Arms that trail behind the galaxy as it rotates. Elliptical – nearly spherical to lens shaped. Their brightness patterns show that most of their stars are close to the center. They have no arms and almost no gas and dust clouds

Irregular Galaxies Smaller, fainter, and less common than the others. Their stars are spread unevenly. With the information that has been provided identify the following galaxies…..

Classify these 3 galaxies. B. Spiral Elliptical C. Irregular Classify these 3 galaxies.