Everything in the Solar System is in Motion A REVOLUTION is an important motion, at which one object moves around another The planets revolve around the sun in paths called ORBITS How long does it take earth to orbit the sun? It takes 365.26 days for the earth to orbit the sun

the apparent shift of position of stars in the sky A parallax helped prove that the earth revolves around the sun, giving us our year length Parallax is a difference in the apparent position of an object viewed along two different lines of sight Pick an object, close your right eye, line your thumb up with the object, now close right eye and open left Unit III Part 1: Weathering and Erosion different types of weathering and erosion hydrological cycle and water’s role in weathering and erosion, glaciation and glaciers’s roles in weathering and erosion Unit III Part 2: Atmosphere and Ocean structure of the atmosphere and weather patterns, typical ocean floor and relation to ocean currents the apparent shift of position of stars in the sky

Paralax & Triangulation - Techniques for Indirectly Measuring Distance uses the geometry of a triangle to find the distance to far away objects. First, a baseline is measured. The longer the baseline, the more accurate the distance measurement will be Next, measure the angles from each end of the baseline to the object. Using mathematic determine the distance the object

Earth Revolution & Tilt this causes short days in winter and longer days in summer; day length doesn’t really vary at the equator aphelion (July) is the point when we are farthest from the sun, perihelion (Jan) when we are closest Unit III Part 1: Weathering and Erosion different types of weathering and erosion hydrological cycle and water’s role in weathering and erosion, glaciation and glaciers’s roles in weathering and erosion Unit III Part 2: Atmosphere and Ocean structure of the atmosphere and weather patterns, typical ocean floor and relation to ocean currents

Kepler’s 1st Law – planets travel in an ellipse with the sun at the focus Unit III Part 1: Weathering and Erosion different types of weathering and erosion hydrological cycle and water’s role in weathering and erosion, glaciation and glaciers’s roles in weathering and erosion Unit III Part 2: Atmosphere and Ocean structure of the atmosphere and weather patterns, typical ocean floor and relation to ocean currents An ellipse has two foci (instead of one like a perfect circle) The further apart the foci are, the more eccentric (non –circular) the orbit is. E = 0, perfect circle E = 1 , perfect ellipse

Kepler’s 2nd Law – radius vector sweep out equal areas in equal times (A1 = A2) Unit III Part 1: Weathering and Erosion different types of weathering and erosion hydrological cycle and water’s role in weathering and erosion, glaciation and glaciers’s roles in weathering and erosion Unit III Part 2: Atmosphere and Ocean structure of the atmosphere and weather patterns, typical ocean floor and relation to ocean currents

(time to orbit the sun)2 = (distance from the sun)3 Kepler’s Third Law of Planetary Motion (harmonic law) states that the square of a planets time to orbit the sun (period) is equal to the cube of its distance from the sun. (time to orbit the sun)2 = (distance from the sun)3 Astronomers like to list the distances to objects within our solar system (planets, dwarf planets, asteroids, comets, spacecraft, etc.) in terms of an astronomical unit. One astronomical unit (AU) represents the mean distance between the Earth and our sun. An AU is approximately 93 million miles (150 million km). Jupiter is ~5.2 AU from the Sun. Therefore, how many earth years does it take to orbit the Sun? T2=R3 time to orbit sun = period = T (in earth years) distance from sun = R (in AUs) T2=(5.2 AU)3 T2=140.6 T= T= ~12 years.

Kepler’s laws of planetary motion