MOTION IN THE UNIVERSE

Earth’s relative motion

DAILY REVIEW1. Kepler’s 1st law states that planetary orbits

are _________________ shapes?2. Kepler’s 2nd law states that 2 equal intervals

of time an imaginary line connecting a planet and the sun will sweep an equal amount of ___________?

3. Kepler’s third law states that the innermost planets orbit ______________________ than the outermost planets.

4. Rotation is the earth spinning on it’s _________________.

5. One trip around the ______________ is called a revolution.

ESSENTIAL STANDARD EEn.1.1 Explain the Earth’s role as a

body in space. EEn.1.1.1 Explain the Earth’s motion through

space, including precession, nutation, the barycenter, and its path about the galaxy. Explain relative motion of the Earth in the

solar system, the solar system in the galaxy, and the galaxy in the universe—including the expanding nature of the universe; Orbital motion (Earth around the Sun- once/year, seasons depend upon an approximate 23.5 degree tilt); Rotation around our axis (day/night,)

ESSENTIAL QUESTION How do galaxies and planets move in

the universe?

MOTIONS OF EARTH Rotation

Turning or spinning of a body on its axis Revolution

Motion of a body along a path around some point in space

PrecessionSlight movement of Earth’s axis

26,000 years

ROTATION Results in day and night

24 hours1,667 km/hr (1,036 mi/hr)

Prove Earth is Rotating? OK!

REVOLUTION Earth moves around the sun in an

elliptical orbitSpeeds around 107,000 km/hr (66,500

mph)Average distance is 150 million kilometers

Perihelion is the point where earth is closest to the sun

Aphelion is the point where earth is farthest from the sun

EARTH’S AXIS AND SEASONS Earth’s axis is tilted about 23.5º on its

axisThis tilt brings the sun 23.5º south of the

equator on the winter solstace This tilt bring the sun 23.5º north of the

equator on the summer solstace

Earth's Seasons

PRECESSION Direction which earth’s axis points

changes very slowly over time without a change in tiltTakes about 26,000 years to complete one

period Currently the axis points toward Polaris

making it the North Star, in 14,000 years Vega will be the North Star.

Precession and polar shift

EARTH-SUN MOTION Earth accompanies the sun as the entire

solar system speeds toward a distant star, Vega

The sun revolves around the galaxyOver 230 million yearsAt 250 km/sec

Now Earth is approaching our nearest galactic neighbor, Andromeda

Earth's not orbiting the sun?!

MOTIONS OF THE EARTH-MOON SYSTEM Earth’s only natural satellite

Orbit’s Earth in one monthWhen viewed from the North Pole, the orbit

is counterclockwiseAverage distance is 384,401 kilometersPoint close to the Earth is PerigeePoint farthest from Earth is Apogee

PHASES OF THE MOON Phases are the

amount of moon that appears lit

Half of the moon is always illuminated

Phases result from the motion of the moon and the sunlight reflected from its surface

Every 29.5 days

Moon Phases

supermoon

TIDES (PG 458) Daily elevation

changes of the ocean surface.

Rhythmic Caused by

gravitational pull of the moon Atmosphere and

ocean are fluids and free to move due to this force.

The sun is further away resulting in less tug

tidal mysterybay of fundy

NUTATION The moon pulls on Earth and Earth pulls

on the moon This pull causes the Earth to wobble on

its axis by about ½ a degree.Changing in the tilt of the Earth’s axis

How does this differ from precession?

gyroscope demo

BARYCENTER Point between 2 or more objects where

they balance each otherPoint where 2 celestial bodies orbit each

other

barycenter

barycenter animation

MORE BARYCENTER When a moon orbits a planet or a planet

orbits a star, both are actually orbiting a point outside the center of the larger body. The moon and earth actually orbit a spot

about 1,710 km below earth’s surface.

MAKE A FLYING GYROSCOPE! A gyroscope rotates allowing you to see precession,

rotation, and nutation Flying gyroscopes are able to fly extremely long

distances You are going to make a flying gyroscope out of

paper! We will launch these gyroscopes outside (weather

permitting or a hallway if not) to see who can get their to fly the farthest

As your gyroscope flies, imagine an axis running through the center of it, and try to see the rotation, precession, and nutation. You will describe it

make a flying gyroscope

EARTH’S SHAPE

EARTH’S SHAPE Not a true sphere Called an oblate spheroid, geoid, or

ellipsoid

CIRCUMFERENCE AND DIAMETER Not equal throughout Poles are squished making a bulge at

the equator Diameter and circumference are greater

at the equator than at the poles.

WHY? Earth’s rotation and gravity Gravity pulls on the mass causing it to

contract Rotation causes earth to flatten due to

centrifugal forceThe force that causes objects to move

outward, away from the center of gravity We call this the coriolis effect

coriolis effect

LOCAL TOPOGRAPHY Topography- study of

surface shape and feature

On a global scale this difference is very small

Mt. Everest is about 8,850 m above sea level

The Mariana Trench is about 10,900 m below sea level

The difference is only about 19,000 m or 12 mi

REMEMBER You have a test on Thursday. We will review tomorrow.