2.1 Do Now Take 15 minutes to complete the do now. Make sure to write your name, date, and 2.1 on top of your paper. Read the Article “New Planet Discovered Similar to Earth” and fill in what you know about the Kepler planet in the appropriate circle: Kepler PlanetEarth

Kepler’s Laws 2.1

Unit 2 Data Tracker

Objective EEn TSW explain the Earth’s motion through space (nutation, barycenter (sun's moving), and precession) by checkpoints and the barycenter lab. EQ: How does the Earth move? What is the difference between precession and nutation?

Who is Kepler? On the top of your notes, write down three interesting facts about Johannes Kepler.

Kepler’s Laws Kepler created 3 laws that discussed how our Earth and the planets move. Today we will learn about Kepler’s 1 st Law of Planetary motion.

Kepler’s 1 st Law: Law of Ellipses Planets move in elliptical orbits with the Sun at one focus.

Why does the Earth move in an ellipse? An ellipse is an oval-shaped figure whose shape is determined by 2 foci. The Sun is at one focus planet’s orbit; the second focus is empty because of the gravitational pull.

How does the Earth move? 1. Rotation 2. Revolution 3. Precession 4. Nutation

Rotation Rotates = spins. 1 rotation=24 hours/ 1 day Looking at the picture below, why is the left hemisphere experiencing a warm day and the right hemisphere experiencing a cooler night? DAY warmer NIGHT cooler

Revolution Revolves (orbits around) the sun 1 revolution= 365 days/ 1 year

Quick Quiz #1 What is the difference between rotation and revolution? A. Rotation is when the Earth orbits around the sun and Revolution is the Earth spinning. B. Rotation gives Earth 1 year (365 days) and Revolution gives Earth 1 day (24 hrs) C. Rotation is when the Earth spins and Revolution is when the Earth orbits around the Sun. D. Rotation moves in an ellipse and Revolution moves in a circle around the sun.

Precession The change in direction of the axis of the Earth, but without any change in tilt -Like the wobbling motion of a spinning top 1 precessional cycle: approximately 26,000 years After viewing the videos, write in where you see precession:

Just like a spinning top!

Quick Quiz #2 Which is the best explanation for precession?  Precession is how the Earth revolves around the sun  Precession is how the Earth spins  Precession takes 1 day to make a rotation  Precession is the change in direction of the Earth’s axis as it rotates

Nutation What do you notice about the movement of the Earth?

Nutation The wobbling/swaying motion during the precession of our axis. This causes a 1 degree change in the tilt of the Earth’s axis.

Quick Quiz #3 What is the best explanation of nutation?  The spinning of the Earth  The wobbling of the Earth’s axis  The change in direction of the Earth’s axis  The orbiting of the Earth around the sun

Kepler’s 2 nd law A planet that speeds up when it is closer to the Sun because of the Sun’s gravitational pull.

Animation

A planet travels the same distance in the same time and but at different speeds (velocities).

Identify the following on the picture: which side is faster?

Quick Check 1. Therefore, Earth moves ________________________ (faster/slower) in summer than in winter, so summer in the Northern Hemisphere must be ___________________________ (longer/shorter) than winter. 2. Isaac Newton later determined that the force of GRAVITY holds the planets in orbit around the Sun. When a planet is closer to the Sun, the force of the Sun’s gravitational attraction on the planet is _________________________ (stronger/weaker) than when the planet is farther from the Sun.

Kepler’s law and Barycenter Barycenter- is the center of mass between two points. All bodies (planets, the sun) in our solar system revolve around a barycenter.

Center of Mass Unbalanced Balanced

So what does this mean? Yes, the sun is the center of the solar system. But the sun and planets are BOTH revolving around the barycenter (the center of mass between them).

Where is the barycenter located? For two objects that are of different masses, the barycenter is CLOSER to the one with MORE mass.

Barycenter Lab

Complete the results and conclusion section of your lab write- up. This will be worth a 30 point project grade. Remember to write in complete sentences!

The time it takes to REVOLVE around the Sun= the distance from the Sun. The farther you are from the sun, the longer it takes to get around the sun. Kepler’s 3 rd Law of Planetary Motion

Just like a track!

The Earth takes ___________ (longer/shorter) than Mercury to revolve around the sun. The Earth takes _____________ (longer/shorter) than Mars to revolve around the sun. For example: Earth

A. Shape of orbit and location of Sun. B. Speed of the Earth and its position in orbit. C. Distance from the sun and length of year. Kepler's third law of planetary motion describes a relationship between the

A. A planet moves faster when its orbit is close to the sun. B. The planet travels faster when it is away from the sun. C. Planets travel in circular orbits Which of these statements about Kepler's Laws is true?

Exit Ticket Complete the Earth section of the Do Now.