Earth and Space

Our Solar System Our solar system is made up of: Sun Eight planets Their moons Asteroids Comets Meteoroids

Inner Planets The inner four rocky planets at the center of the solar system are: Mercury Venus Earth Mars

Mercury Planet nearest the sun Second smallest planet Covered with craters Has no moons or rings About size of Earth’s moon

Venus Sister planet to Earth Has no moons or rings Hot, thick atmosphere Brightest object in sky besides sun and moon (looks like bright star) Covered with craters, volcanoes, and mountains

Earth Third planet from sun Only planet known to have life and liquid water Atmosphere composed of composed of Nitrogen (78%), Oxygen (21%), and other gases (1%).

Mars Fourth planet from sun Appears as bright reddish color in the night sky Surface features volcanoes and huge dust storms Has 2 moons: Phobos and Deimos

Outer Planets The outer planets composed of gas are : Jupiter Saturn Uranus Neptune

Pluto Dwarf Planet Never visited by spacecraft Orbits very slowly

Asteroids Small bodies Believed to be left over from the beginning of the solar system billions of years ago 100,000 asteroids lie in belt between Mars and Jupiter Largest asteroids have been given names

Comets Small icy bodies Travel past the Sun Give off gas and dust as they pass by

Meteoroids Meteoroid: A small particle from a comet or asteroid orbiting the Sun. Meteor: The light phenomena which results when a meteoroid enters the Earth's atmosphere and vaporizes; a shooting star. Meteorite: A meteoroid that survives its passage through the Earth's atmosphere and lands upon the Earth's surface.

Rotation versus Revolution Rotation Rotation is the turning of a body about an axis. The earth rotates once every 24 hours. Revolution Revolution is the motion of one body around another. The earth revolves around the sun once every 364 ¼ days.

Why Do We Have Seasons? tilt of the Earth’s axis revolution around the Sun The tilt of the Earth’s axis and the revolution around the Sun cause the Earth to have seasons.

Combined Effects of Tilt and Revolution

Earth’s Seasons - Year

Why Does The Moon Have Phases? Phases of the moon are determined by: The relative positions of the earth, moon and sun. Revolution of moon around the earth. Your position on the earth.

Instruments and technology used in astronomy

Refracting telescope: collects & amplifies light using lenses Reflecting telescope: collects & amplifies light using mirrors Binoculars: uses two refracting telescopes to observe 3D objects Radio telescope: collects & amplifies radio waves emitted by celestial bodies Radar: measures the distance between the Earth and celestial bodies Observatory: building that provides the best possible conditions to observe the universe Satellite: object place around a celestial body to collect/transmit data

Instruments and technology used in astronomy Space probe: Unmanned spacecraft launched into space to explore celestial bodies Space rocket: Unmanned spacecraft launched into space, with only one salvageable section Space shuttle: A salvageable spacecraft launched into space capable of returning to Earth Space station: A facility place in orbit around the Earth (or other celestial body) that is designed for habitation and to carry out various missions

Measurements in astronomy AU: Astronomical unit = 150 million km Distance between the Earth and the Sun Light year: billion km

Pluto (not a planet) The 2006 debate surrounding Pluto and what constitutes a planet led to Ceres being considered for reclassification as a planet. A proposal before the International Astronomical Union for the definition of a planet would have defined a planet as "a celestial body that (a) has sufficient mass for its self-gravity to overcome rigid-body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (b) is in orbit around a star, and is neither a star nor a satellite of a planet"

Ceres (not a planet) However, and on 24 August 2006 a modified definition was adopted, carrying the additional requirement that a planet must have "cleared the neighborhood around its orbit". By this definition, Ceres is not a planet because it does not dominate its orbit, sharing it as it does with the thousands of other asteroids in the asteroid belt and constituting only about a third of the mass of the belt. Bodies that met the first proposed definition but not the second, such as Ceres, were instead classified as dwarf planets.

Solar system A solar system refers to a star and all the objects that travel in orbit around it. Our solar system consists of the sun - our star - eight planets and their natural satellites (such as our moon); dwarf planets; asteroids and comets. Our solar system is located in an outward spiral of the Milky Way galaxy.

Solar system

Galaxy a system of millions or billions of stars, together with gas and dust, held together by gravitational attraction.

ICW/Homework P.293 #1,2,5,6,7 P.294 #10,11,18 P.295 #22,25