650 likes | 1.31k Views
Motion of the Earth. Orbit? Rotation? Revolution?. What is a Rotation?. Rotation is the spin of a planet. A rotation is the movement of something through one complete spin. The Earth goes through one complete rotation in a day = 24 hours. Orbit? Rotation? Revolution?.
E N D
Orbit? Rotation? Revolution? • What is a Rotation? • Rotation is the spin of a planet. • A rotation is the movement of something through one complete spin. • The Earth goes through one complete rotation in a day = 24 hours
Orbit? Rotation? Revolution? • What is a Revolution? • A revolution is the path that a planet follows around the sun. Also known as an orbit. • The Earth completes one revolution around the sun every year.
Orbit? Rotation? Revolution? • What is an Orbit? • An orbit is the curved path in space that is followed by an object going round and round a planet, moon, or star.
What is Earth’s orbit shaped like? • Earth’s orbit is shaped like an ellipse not a circle. Ellipse Circle
Why do we have seasons? • Many uninformed people blame the seasons on the shape of the Earth’s orbit. Stating that it is warmer in the summer because we are closer to the sun. • THIS IS NOT TRUE!!!! • It is Wrong in two ways
2) The real reason we have seasons is due to the tilt of Earth’s axis
1 KW/m2 1 KW/m2 1 m2 2 m2 In winter light is spread over a bigger area than in summer Due to the inclination away from the Sun
What is an equinox? • An equinox is one of the two days in the year when day and night are of equal length. • They usually occur on March 20th or September 22nd
What is the vernal equinox? • What is the autumnal equinox • The vernal equinox occurs in march. For the northern hemisphere it is the spring equinox • The autumnal equinox occurs in September, or in the fall for the northern hemisphere
Winter and Summer Solstice • What is a solstice? • Thesummer solstice is the day of the year with the most hours of daylight, and thewinter solstice is the day of the year with the fewest hours of daylight.
Solar and Sidereal Day • How long is one day ? • From noon (Sun directly overhead) to noon ?
T=24h (Solar day) T=23h 56m 04s (Sidereal Day) Noon Noon Solar & SiderealDays T=0h Not to Scale
Precession of the Earth’s axis • What is the Earth’s axis • The Earth’s axis is the imaginary line going through the Earth that it rotates around
Precession of the Earth’s axis • What is precession? • Precession is a change in the orientation, or direction, of the rotation axis of a rotating body.
Precession of the Earth’s axis • The Earth’s axis also follows a precession. The axis of the Earth will point in a different direction in the future