EARTH'S ROTATION AND REVOLUTION

Earth’s Rotation Rotation is the spinning of the Earth on its axis. You notice this when day turns to night The time for one rotation is 24 hours. The speed of rotation 24,855 miles/24 hr or 1,038 miles/hr Click image to view Earth’s rotation.

Earth’s Revolution A revolution occurs as the earth moves around the sun. Time for one revolution = 365 1/4 days = 8,766 hours This is why we have leap years every 4 years, to make up for the ¼ day. The speed of earth’s revolution is about 29.8 km/s or 18 miles per second.

Around and Around We Go Every second, that you sit in this classroom, the Earth's orbital motion carries you about 18 miles through space.

Earth’s Orbit The path an object takes as it revolves around another object. Earth’s orbit is in the shape of an eclipse. Because of this, earth is not always the same distance away from the sun When the Earth is closest to the Sun: perihelion When the Earth is farthest from the Sun: aphelion Earth’s aphelion is about 152 million km away vs. 147 during perihelion.

Constellations and Earth’s Motions A constellation is a group of stars that are organized in a recognizable pattern. Today there are around 88 recognized constellations, many come from the ancient Greeks.

Evidence of Rotation and Revolution Earths rotation make the constellations appear like they are moving in the shape of an arc Revolution During different seasons, the constellations are in different locations in the night sky.

Measuring Time They way that the Earth revolves and rotates determines “time” We say one day is equal to one rotation around Earth’s axis and a year is defined as one revolution around the sun. A month is based on the moon’s motion around Earth. Determined by the period between successive full moons (29.5 days). However, now a year is just broken into 12 months (number of full moons in a year not always a whole number)

Moon Cycle

Time Zones We define noon as the time when the sun is highest in the sky, but because of earth’s rotation the sun is highest above different locations at different times of day. 24 standard time zones Time set based on noon being when the sun is the highest. About every 15 degrees (total 360) is a new time zone.

Time Zones

Daylight Saving’s Time Because of the tilt of the Earth, the duration of daylight is shorter during winter months compared to summer months. To take advantage of this, we set clocks 1 hour ahead in March in order to get an additional hour of sun at night and in November clocks are set back in order to return to standard time. Not all counties participate in Daylight Savings time.

The Seasons Earth’s Axis is tilted at 23.5%. Earth’s Axis always points toward the North star as it revolves around the sun. When the North Pole points toward the sun, the northern hemisphere has longer periods of daylight than the southern hemisphere. Higher concentration of solar energy=warmer When the North Pole points away from the sun, the Southern Hemisphere has longer periods of daylight. Not as high concentration of solar energy=cooler

Seasons

Equinox The moment when the sun passes over the celestial equator. The Seasons Fall and Spring begin on days called equinoxes. The moment when the sun passes over the celestial equator. Imaginary line directly overhead the equator. Sun strikes equator at 90 degree angle Hours of sunlight and darkness are equal everywhere on Earth that day. Autumnal equinox: September 22, 23 (fall in N. hemisphere Vernal equinox: March 21, 22 (Spring in N. Hemisphere

Solstices Summer Winter June 21 or 22 is when the North Poles tilt toward the sun is the greatest. Marks beginning of summer in the N. Hemisphere. The N. Hemisphere has the most hours of daylight during this day. The farther north you are, the longer day you have. North of arctic circle you have 24 hours of sunlight. Winter By December 21, 22 the North Pole is tilted to the farthest point away from the sun. Winter Solstice marks the beginning of winter in the N. Hemisphere. During the winter solstice, the N. Hemisphere has the shortest amount of daylight hours. Places north of the arctic circle have 23 hours of darkness

Extension: Video: https://www.youtube.com/watch?v=82p- DYgGFjI Homework: Quiz over oceans on Wednesday…study

Round One 1. The Earth spinning on its axis. Rotation Revolution 2. Going around a larger body. Rotation Revolution Revolution 3. 24 hours. Round One Rotation Revolution 4. Causes the Earth’s seasons. Rotation Revolution 5. Creates a year. Rotation Revolution 6. The moon going around Earth. Rotation Revolution

Identify the motion being shown in each of these pictures Identify the motion being shown in each of these pictures. Each team must write their answers for each figure in the form of a question. Figure #1 Rotation Revolution Planet Round Two Figure #2 Earth Rotation Revolution