Earth and Space

Earth’s Place in Space *Earth moves around the sun. A. Earth’s Rotation Earth spins around an imaginary line running through its center called an axis. It is slightly tilted. The spinning of Earth on its axis is called Earth’s rotation. It rotates once every 24 hours (1 day and night).

B. Earth’s Revolution The movement of Earth around the sun in known as Earth’s Revolution. It takes Earth 1 year to complete one revolution.

C. Seasons The Earth’s tilt and revolution around the sun causes seasons. Summer occurs when your part of the Earth is tilted towards the sun. The days are long and the nights are short. Winter occurs when your part of the Earth is tilted away from the sun and the slanted rays of the sun are weak. The days are short and the nights are long. Spring and fall occur when Earth is not tilted toward or away from the sun.

D. Movements of the Moon The moon constantly circles the Earth as Earth revolves around the sun. Although it looks different at different times of the month, it doesn’t change – the way we see it does. The sun lights up the moon. The movement of the Earth is what causes night and day.

D. Movements of the Moon (cont.) When the moon and sun are on opposite sides of Earth, a full moon occurs. When the moon and sun are on the same side as Earth, a new moon occurs. This is when the side of the moon that is lit by the sun faces away from Earth. Full Moon New Moon

Phases of the Moon

Diagram of a Solar Eclipse Solar eclipse: when the moon is between the Earth and Sun. Diagram of a Solar Eclipse Total Solar Eclipse (2001)

Stages of a Lunar Eclipse Lunar eclipse: when the Earth is between the sun and moon. Stages of a Lunar Eclipse

Space – How are we connected? Universe Galaxy Milky Way Our Solar System

The Universe (several galaxies can been seen) Universe: the vast expanse of space which contains all of the matter and energy in existence. EVERYTHING is a part of it. IT IS HUGE!!! Galaxy: a cluster of starts, dust, and gas which is held together by gravity. Astronomers suggest there may be as many as 100 billion!! They are scattered throughout the universe and vary greatly in size. The Universe (several galaxies can been seen) Spiral Galaxy

1. irregular – no definite shape *Galaxies are classified by scientists according to their size and shape. 1. irregular – no definite shape 2. spiral – pinwheel shape (our galaxy) 3. elliptical – go from round to flat discs *galaxies range from a few thousand to a million light years in diameter. Spiral (Andromeda) Elliptical Irregular

Solar System Made up of 8 planets and other objects that orbit the sun. To measure distances in space, scientists use an astronomical unit (AU). 1 AU = 150 million km, which is the average distance from Earth to the sun. A light year is 9.5 trillion (9,500,000,000,000) kilometers and is the distance light travels in one year.

Planet: round ball of gas or rock that travels around a star – and the path it takes around a star is called its orbit. Inner Planets: Mercury, Venus, Earth, Mars

Outer Planets: Jupiter, Saturn, Uranus, Neptune.

Saturn is not the only planet with rings Saturn is not the only planet with rings. Jupiter, Uranus, & Neptune do too. Pluto is now considered a dwarf planet.

The Stars and Sun The stages a star goes through in its life depend on the star’s size. The smallest stars shine the longest. Scientists hypothesis that stars begin their lives as nebulae (clouds of gas and dust). A large-size star can end its life cycle as a neutron star or a black hole. The sun is a medium-sized star.

The Stars and Sun, cont. In about 5 billion years our sun will become a giant. At the end of our sun’s life cycle, it will become a black dwarf.

The Sun and Stars, cont. Constellations: patterns formed by groups of stars. *They are named for people, animals, or commons objects and were used as reference points in the sky by sailors. *Because the Earth is moving, the stars that are visible at night constantly change. *As the Earth revolves around the sun, different constellations are seen throughout the year.

Examples of Constellations… The Big Dipper (Ursa Major) The Little Dipper (Ursa Minor)

Our Galaxy Our galaxy is called the Milky Way. The shape of our galaxy is spiral (looking down it looks like a pinwheel) It contains: stars (billions!), nebulae (clouds of dust and gas), planets, and asteroids. It is approximately 100 light years in diameter. All objects in the Galaxy revolve around the Galaxy’s center. It takes the Sun 250 million years to pull us through 1 revolution around the center of the Milky Way.

The Milky Way Galaxy