Why does Earth seem to be Why does Earth seem to be standing still?standing still?

• Because you move along with it.Because you move along with it.

• Earth moves slowly and steadily.Earth moves slowly and steadily.

What are 2 clues that Earth What are 2 clues that Earth moves?moves?

• Stars seem to move across the sky.Stars seem to move across the sky.

• The seasons change.The seasons change.– Seasons change during the year Seasons change during the year

because Earth is tilted on its axis and it because Earth is tilted on its axis and it orbits the sun.orbits the sun.

What causes day and night?What causes day and night?

• When a place on Earth is turned toward When a place on Earth is turned toward the sun it is day.the sun it is day.

• When a place on Earth is turned away When a place on Earth is turned away from the sun it is night.from the sun it is night.

• Earth rotates from west to east.Earth rotates from west to east.

Earth’s RevolutionEarth’s Revolution

• A complete trip around the sun is one A complete trip around the sun is one revolution.revolution.

• Earth takes 1 year or about 365 days to Earth takes 1 year or about 365 days to complete one revolution.complete one revolution.

• As Earth orbits the sun, its distance from As Earth orbits the sun, its distance from the sun changes.the sun changes.

• Gravity between the Sun and Earth keeps Gravity between the Sun and Earth keeps Earth revolving.Earth revolving.

• Without gravity, Earth would fly off into Without gravity, Earth would fly off into space.space.

Why is it summer in the Northern Why is it summer in the Northern Hemisphere when it is winter in the Hemisphere when it is winter in the

Southern Hemisphere?Southern Hemisphere?

• During summer in the Northern During summer in the Northern Hemisphere, the North Pole is tilted Hemisphere, the North Pole is tilted toward the sun and gets more direct toward the sun and gets more direct sunlight, while the South Pole tilts sunlight, while the South Pole tilts away from the sun and gets less away from the sun and gets less direct sunlight.direct sunlight.

What causes Earth’s What causes Earth’s seasons?seasons?

• Earth’s axis is tilted so Earth’s axis is tilted so that the end tilting that the end tilting toward the sun has toward the sun has Spring and Summer. The Spring and Summer. The end tilted away from the end tilted away from the sun has Winter and Fall.sun has Winter and Fall.

• Earth revolves around the Earth revolves around the sun resulting in Earth’s sun resulting in Earth’s axis being tilted toward axis being tilted toward the sun 1/2 the year and the sun 1/2 the year and away from the sun the away from the sun the other ½ of the year.other ½ of the year.

Moon PhasesMoon Phases

• The changing phases of The changing phases of the Moon depend upon the the Moon depend upon the positions of the Sun, Moon, positions of the Sun, Moon, and Stars.and Stars.

• The Moon rotates once on The Moon rotates once on its axis at about the same its axis at about the same rate that it revolves once rate that it revolves once around Earth.around Earth.

• Different amounts of the Different amounts of the lighted half of the Moon lighted half of the Moon facing the Earth causes the facing the Earth causes the apparent changes of the apparent changes of the Moon’s shape.Moon’s shape.

EclipsesEclipses

• An eclipse occurs when one An eclipse occurs when one object in space comes between object in space comes between the Sun and another object.the Sun and another object.

• Lunar and solar eclipses can be Lunar and solar eclipses can be seen from Earth.seen from Earth.

• A solar eclipse occurs when the A solar eclipse occurs when the Moon, Sun, and Earth are in-Moon, Sun, and Earth are in-line with each other. line with each other.

• In a lunar eclipse the Moon In a lunar eclipse the Moon passes through Earth’s shadow.passes through Earth’s shadow.

StarsStars

• The Sun is a medium-The Sun is a medium-sized star close to the sized star close to the Earth.Earth.

• All stars, including the All stars, including the Sun, are hot balls of gas.Sun, are hot balls of gas.

• Apparent patterns of Apparent patterns of stars are called stars are called constellations.constellations.

• Distance between the Distance between the stars seem close stars seem close together, but they are together, but they are actually far apart.actually far apart.

EssayEssay

• What causes the phases of the Moon What causes the phases of the Moon to change in the same pattern to change in the same pattern approximately every 29 days?approximately every 29 days?– As the Moon revolves around Earth, As the Moon revolves around Earth,

different parts of the Moon are struck by different parts of the Moon are struck by sunlight, which then reflects off of the sunlight, which then reflects off of the Moon’s surface. As different parts of the Moon’s surface. As different parts of the Moon’s surface are struck by sunlight, Moon’s surface are struck by sunlight, different phases of the Moon can be seen.different phases of the Moon can be seen.