Earth’s Motion

Do Now What is the shape of a planet’s orbit? Describe how the planets of the solar system formed. A galaxy is __________. The modern heliocentric model states that the planets travel around the ____ in a _______ orbit. Two types of evidence for the big bang theory include __________.

Lesson Essential Question How does the Earth move? (Rotation, Revolution, Precession, Nutation)

Notes on the Universe The universe is made of galaxies which are made of many stars. Some stars have planetary systems similar to our solar system. Earth is a satellite planet of one particular star (our sun)

ROTATION Rotation – turning or spinning on it’s axis Rotations CAUSE DAY and NIGHT Earth rotates as it orbits AROUND the SUN Spins Counterclockwise one day to equal 24 hours

The Earth’s Axis The tilt of the axis is responsible for SEASONS The axis moves counterclockwise The Earth’s axis has a tilt of 23.5 degrees When the axis is tilted TOWARDS the sun = WARM seasons in the NORTHERN HEMISPHERE and COOL seasons in the SOUTHERN HEMISPHERE

Revolution Revolution – the motion of a body along a path around some point in space Earth’s orbit is an elliptical Earth orbits (revolves) the sun ONCE a year

Precession The direction this axis of a planet is pointing in will change, but the tilt will not change. This will change the stars near the pole but will not change the seasons (as long as the angle of the tilt, 23.5 in the case of Earth, stays the same) The Earth’s axis points to two stars: Polaris and Vega

Nutation Nutation happens when the axis of a planet starts to wobble The angle of the axis will change during nutation ½ degree one direction or the other Nutation happens over the course of 18 years Nutation is a direct result of the moon (or moons) of a planet

How it works…DRAW this diagram!

Let’s Take a Look Rotation and Revolution

Barycenter Barycenter – the point between 2 objects where they balance each other The center of mass where 2 or more celestial bodies orbit each other. KEY POINT – the Barycenter is CLOSER to the object that has the GREATER MASS.

The sun is NOT stationary in our solar system. It moves as the planets tug on it causing it to orbit the solar systems’ barycenter. The sun never strays too far from the solar system.

Exit Ticket 1. Identify the evidence that supports the Earth’s rotation. 2. What is the reason for Earth’s spheroidal shape (wider at the equator)? 3.

Summary of Rotation and Revolution

Rotation – Revolution Contrast & Comparison Contrasts Comparisons Revolution vs. Rotation Revolution= object moves around another object Rotation = an object spin in one place Orbit vs. Revolution Orbit = path that object takes around another object Revolution = object moves around another object Revolution vs. Rotation Both involve circular movement Orbit vs. Revolution The orbit is the path that an object takes while it is revolving another object

Rotation – Revolution Contrast & Comparison cont. Contrasts Comparisons Rotation, vs. Rotation Axis vs. Equator Rotation = spinning of an object Rotation Axis = point on Earth where the spinning occurs Equator = imaginary line that circles the middle of the Earth Rotation, vs. Rotation Axis vs. Equator The rotation of Earth occurs on the rotation axis The equator is the midway point between the North and South Rotation axis

Rotation – Revolution Contrast & Comparison Contrasts Comparisons Solstice vs. Equinox Solstice = occurs when the Northern and Southern hemispheres have opposite weather (during summer and winter). Equinoxes = occurs when the northern and southern hemispheres have equal weather (spring and fall) Solstice vs. Equinox Solstices and Equinoxes alternate seasons (spring equinoxes, summer solstice, fall equinoxes, winter solstice)

Seasons

December Solstice The north end of Earth’s axis leans away from the sun = Winter Solstice In the Northern Hemisphere = Winter In the Southern Hemisphere = Summer Temperatures are cooler in the Northern Hemisphere because solar radiation is more spread out and less concentrated during this time.

March Equinox The number of daylight hours is 12 hour day and 12 hours night In the Northern Hemisphere = Spring In the Southern Hemisphere = Fall The sunlight is distributed equally during this time

June Solstice The north end of the Earth’s axis leans towards the sun = Summer Solstice In the Northern Hemisphere = Summer In the Southern Hemisphere = Winter The temperatures is higher because the solar radiation is more concentrated during this time.

September Equinox The number of daylight hours during the Fall is 12 hours of daylight and 12 hours of night In the Northern Hemisphere = Fall In the Southern Hemisphere = Spring The sunlight is distributed equally

Eclipses

Eclipses Eclipse – when an object passes between the observer and the object that emits light. Two types – Solar (sun) and Lunar (moon)

Solar Lunar The Moon blocks solar radiation from the Sun and solar radiation is blocked from reaching the Earth’s surface During Solar Eclipse – the position of the Sun, Moon, and Earth are in a STRAIGHT LINE…in THAT order The Earth blocks solar radiation from the Sun and solar radiation is blocked from reaching the Moon’s surface During Lunar Eclipse – the position of the Sun, Earth, and Moon are in a STRAIGHT LINE…in THAT order

What are tides? Tides are changes in the elevation of the oceans surface

Tides What causes tides? What is a spring tide? What is a neap tide? Gravitational pull of the Sun and Moon What is a spring tide? When the high tide is higher than the normal tide because the Moon, Sun, and Earth are aligned in a straight line in the same direction. What is a neap tide? When the high tides are lower than normal tide because the Moon, Sun, and Earth are not aligned in a straight line in the same direction (right angle/perpendicular)

When do tides occur in relation to the moon? Spring tides - occur during NEW and FULL moon because the GRAVITATIONAL forces are ADDED together. Neap tides - occur during 1st and 3rd quarter moon because the GRAVITATION forces are OFFSET

What does it look like?

Tidal patterns

Tidal Pattern 1 Diurnal = Daily One HIGH tide and One LOW tide each lunar day Lunar day – tides occur 50 minutes later due to the rotation pattern of the Earth and the moon.

Tide Pattern 2 Semidiurnal – TWO high and TWO low tides. Each high and low tides are similar to each other Occurs in the Atlantic Coast

Tidal Pattern 3 Mixed – TWO high tides and TWO low tides each day. Each high and low tides are DIFFERENT from each other Occurs on the West Coast