What are Stars and Planets? UNIT D THE SOLAR SYSTEM What are Stars and Planets?

An astronomer is a person who studies the universe.

THE NIGHT SKY Did you ever notice the sky on a clear night? There are many stars, too many of them to count. They look like small dots of light in the sky. They only look small because they are so far away. Stars are really much bigger than Earth.

STARS A star is a big ball of hot gases. The hot gases give off light. This light is what we see from Earth. They also give off heat. The sun is the closest star to Earth. Did you ever wonder why some stars are bigger and brighter than other stars?

The brightness of a star depends on their size, their heat, and their closeness to Earth. All stars are not the same sizes and temperatures. The bigger and hotter a star is, the brighter it will be. A stars closeness to Earth will also make it brighter. The closer a star is to Earth, the brighter it will be.

THE SUN

FACTS ABOUT THE SUN The sun is a star. It is the closest star to Earth. The sun is much larger than the Earth. It only looks smaller because it is so far away. Like other stars, the sun is made of hot gases. Because these gases are so hot, they give off light and heat.

Some people use a telescope to look at the night sky. A telescope makes stars look closer and larger.

CONSTELLATIONS A group of stars that form a star picture is called a constellation. Long ago, people saw pictures in these groups of stars. They began naming the different star pictures. There are about 88 constellations in the entire sky.

Let’s look at some of our constellations……

Big Bear and Big Dipper The Big Bear (Ursa Major) constellation contains a group of seven stars called the Big Dipper. Together these stars form the shape of a dipper, a kind of spoon. www.coe.uh.edu/.../constellations.htm

Polaris, or the North Star, can be found at the end of the handle of the Little Dipper. People long ago used it like a compass because it was so easy to spot, and always leads you to the north.

Orion the Hunter….. Can you see the shoulders, belt with sword hanging, the bow, and his hand pulling back the bow????

THE SOLAR SYSTEM The sun is the closest star to Earth. Eight planets, including Earth, move around the sun. A planet is a large ball of rock or gas that travels around the sun. Together, the sun, the planets, moons, comets, asteroids, and meteoroids make up our solar system. The sun is the only star in our solar system.

OUR GALAXY Our galaxy is the Milky Way Galaxy. The Milky Way galaxy includes the entire solar system and hundreds of billions of stars.

Mercury the planet closest to the sun. Small rocky and hot planet Dusty surface with craters Looks like Earth’s moon 36 million miles from sun www.starchild.gsfc.nasa.gov/

Venus is second planet from the sun. Can be seen shining in the night sky Dry ,hot planet with tall mountains and deep valley Thick yellow clouds, blown around by strong winds About the size of Earth 67 million miles from sun

Earth, our planet, is the third planet from the sun. Almost cover by water Ball of rock Not too hot or too cold Only planet with plants and animals 93 million miles from sun

Mars is the fourth planet from the sun. Desert, except for ice caps at each end Tall mountains and deep canyons Red planet(soil full of rust) Strong winds blow up red dust 141 million miles from sun

Jupiter is the fifth planet from the sun. Biggest planet Ball of gas, rocky center Yellow, tan, red, orange, and white clouds blown by strong winds Giant red spot, scientists think it’s a storm) 483 million miles from sun

Saturn is the sixth planet from the sun. Ball of colored gas Rocky center Pretty rings made of bits of ice and rock 885 million miles from sun

Uranus is the seventh planet from the sun. Gas planet, rocky center Thin, dark rings Blue-green color Covered by thick haze Tilted on side, moves around the sun like a rolling ball 1billion 779 million miles from sun

Neptune is the eighth planet from the sun. Gas planet Center of rock and iron Greenish color Cover with clouds 2 billion 788 million miles from sun

What about Pluto? After it’s discovery in 1930, Pluto was considered the ninth planet in the solar system. From 1930 until 2006, we had limited information about Pluto. We did not gain a realistic understanding of it’s characteristics until 2006. In 2006, Pluto was classified as the 2nd largest known dwarf planet. There are just 5 known dwarf planets at this time. But, scientists know there are many more to be discovered.

Meteoroids Meteoroids are made of small chunks of rock and ice.

Asteroids Asteroids are chunks of rock and metal.

Comets Comets are frozen balls of dirty ice.