Earth and Space Science ESS 1 5 OBJECTS

Earth and Space Science ESS. 1. 5 OBJECTS IN THE UNIVERSE

Vocabulary • Sun – The closest star to Earth • Earth – 1 of 8 planets orbiting the Sun • Moon – a natural satellite orbiting a planet

• Star – A ball of hot gas which produces heat and light. Stars come in different brightnesses and sizes. • Planet – An object with its own gravity orbiting a star • Solar System - A star and everything orbiting that star • Galaxy – A huge collection of stars (millions and millions), gas and dust. Our solar system is in the Milky Way galaxy. The Milky Way is about 100, 000 light years across. • Universe – A collection of millions of galaxies • The Universe Video

Stars • Most stars are made of hydrogen gas • The color of a star is related to the temperature it is burning at The hottest stars are white or blue The cooler stars are orange or red

Brightness of a Star • How much energy a star puts out is called luminosity • Distance from Earth and luminosity determine how bright a star is. The farther away a star, the less bright it appears.

The Sun • Contains 98% of our Solar System’s mass • Right now the sun is about 90% hydrogen and 8% helium and 2% metal • The sun is about 4. 5 billion years old • Mass: 1, 989, 100, 000, 000, 000 kg • Distance from Earth: 149, 597, 900 km • Rotates once about every 25 days http: //solarsystem. nasa. gov/planets/profile. cfm? Object=Sun

The Earth • Earth is an English/German word meaning ground • Third planet from the sun • About the same size as Venus • Mass: 5, 972, 190, 000, 000 kg • Orbits the sun every 365. 26 Earth days

70% of Earth’s surface is covered by water Much of Earth’s weather comes from the heating and cooling of water in the atmosphere

Earth Revolves Around the Sun • Each year, Earth goes around the sun one time • Earth travels in an ellipse (not a perfect circle) Geography for Kids Video

• Earth is tilted at an angle as it rotates around the sun

Animation of Earth’s annual orbit around the sun

The Moon • A natural satellite in Earth’s orbit • Other planets have moons also – Jupiter for example has 67 moons (4 large and 63 small)

• We don’t know how it was formed, but maybe Earth collided with another planet sized objects and the debris from the crash pulled together to form the moon How Moon craters may have formed Video

• We always see the same side of the moon

The Moon’s rotation Video

Phases of the Moon • The moon passes through 8 phases every 29. 5 days History Channel: Phases of the Moon http: //www. youtube. com/watch? v=n. Xse. TWTZlks Ask an Astronomer: Why Does the Moon Look Like it Changes? http: //www. youtube. com/watch? v=Yd. I 1 a. Dj. WLl. Y

NEW MOON • The visible moon is not fully illuminated by direct sunlight.

WAXING MOON • A waxing moon is when a moon appears to be growing larger. Waxing Crescent is less than ½ illuminated Waxing Gibbous is more than ½ illuminated

First quarter • This is when exactly ½ of the face of the moon is lit and the moon is still “growing”. • Occurs between a waxing crescent and waxing gibbous

FULL MOON • The visible moon is fully illuminated by direct sunlight.

WANING MOON • A waning moon is when a moon appears to be getting smaller. Waning Gibbous is more than ½ lit and is getting smaller. Waning Crescent is less than ½ lit and is getting smaller.

Last or Third Quarter Moon • This is when ½ the face of the moon is lit between a waning gibbous and waning crescent. The moon is getting smaller.