Solar System Sun is at the center, other objects orbit it Sun is a star Orbit- path an object takes around the sun 8 planets Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Pluto Inner Planets Outer Planets

Solar System Moons- bodies that orbit planets Earth has one moon Jupiter and Saturn have many moons Mercury and Venus-no moons Asteroid- small rocky bodies that revolve around the sun, most found in asteroid belt Comet- made up of ice, dust and small gritty particles, have “tail”, many come from Oort cloud, beyond Pluto Meteroid- small particles of rock, most come from asteroids or comets, produce streaks of light called meteors, when they land on Earth they are called meteorites

Solar system Review 1.) Which statement best describes how the sun and Earth are related? a. Earth revolves around the sun b. The sun revolves around the Earth c. Earth rotates around the sun d. The sun rotates around Earth 2.) Which list gives the inner planets in correct order starting with the planet closest to the sun? a. Mercury, Earth, Venus, Mars b. Venus, Earth, Mars, Mercury c. Mercury, Venus, Earth, Mars d. Mars, Venus, Earth, Mercury 3.) Which of the following is a rock from space that lands on Earth? a. Meteoroid c. comet b. asteroid d. meteorite 4.) Which of these does NOT describe an outer planet? a. rocky c. has many moons b. has rings d. gasous

The sun and other Stars Star- a sphere of hot glowing gases that gives off its own light and is held together by gravity Sun =Medium star by size and mass, yellow in color, surface temp 5,500oC, diameter 1.4 million kilometers, mass 1.99 x 1030 kg Sun- contains 99.8% of the mass of our solar system, the sun is a star, made of mostly hydrogen gas Nuclear Fusion- process that provides sun’s energy In nuclear fusion, two atoms of hydrogen combine to form helium producing extreme amounts of energy

The Sun and Other Stars Temperature of a star determines its color Brightness determined by size and temperature Absolute magnitude- describes actual brightness if it were a standard distance from Earth, measured from -10 to +15 (negative=brighter) Color Temperature 30,000oC 9,500oC 6,000oC 5,000oC 3,000oC

The sun and other stars HR Diagram Most stars fall with in diagonal band of stars called main sequence. These stars show a direct relationship between temperature and brightness Hotter stars burn brighter. Cool red giants in the upper right are bright because of their size Hot white dwarfs are dim because they are so small

The Sun and Other Stars Life Cycles of Stars Stars form when clouds of gas become compressed enough to start the process of nuclear fusion, **Its mass determines its life cycle Most stars enter the main sequence phase *lasts about 10 billion years, nuclear fusion powers these stars **HOT STARS USE OF THEIR HYDROGEN FASTER THAN COOL STARS Stars leave main sequence Low mass left—collapse and become white dwarf Medium mass- enters period of expansion and contraction, use helium as fuel, becomes red giant, after about a billion years collapses to white dwarf, then cools to black dwarf Very Massive- become super giant (huge, cool, red stars), helium and carbon used as fuel, if massive enough will collapse to neutron star when it dies, most massive collapse into black holes (an object so dense light cannot escape from it) Sun main sequence star about 4.6 billion years old, will burn hydrogen for about 5 billion more years then it will become a red giant and burn helium when helium runs out fusion will stop red giant will become white dwarf the sun will continue to give off energy as it cools into a black dwarf

The sun and other stars review 1.) What kind of star is our sun? a. supergiant c. white dwarf b. red giant d. main sequence 2.) Which of the following is MOST important in determining a star’s life cycle? a. its mass c. its color b. its diameter d. its brightness 3.) What fuel does a main-sequence star use for nuclear fusion a. oxygen c. helium b. petroleum d. hydrogen

Days, Years, and Seasons Length of year-time in which a planet completes on orbit around the sun 365 days Planets that are farther from the sun have longer years than those closer to the sun Length of day-time in which a planet makes on full turn on its axis 24 hours Length of day varies among the planets Seasons-variation in length of day and temperature based amount of sunlight received Amount of sunlight affected by tilt of the Earth on its axis Summer Solstice Autumnal Equinox Winter Solstice Vernal Equinox **Equinox  equal

Phases of the Moon Phases of the moon: Same side of moon always faces the Earth Moon takes the same amount of time to orbit Earth as it does to turn on its axis Moon’s orbit around Earth is angled so an eclipse does not occur often At any time half the moon is lit, half the time its dark Waxing- sunlit part of the moon grows larger Waning- sunlit part of the moon grown smaller

Tides Tide- rise or fall of surface of water due to gravitational force High tide-highest level of water along shore Low tide-lowest level of water along shore Spring Tide-moon, sun, and earth in line during new or full moon, greatest difference between high and low tide Neap Tide-moon, sun and earth at right angles during new or full moon, least differences between high and low tide http://oceanservice.noaa.gov/education/tutorial_tides/media/supp_tide06a.html

Eclipses Solar Eclipse-moon blocks sun’s light and casts a shadow onto Earth Only occurs during new moon Moon passes between sun and Earth Umbra-area of total eclipse, sky becomes dark as night Penumbra-area of partial eclipse, not as dark as

Eclipses Lunar Eclipse-moon passes into Earth’s shadow Earth is between sun and moon, this blocks sun’s light from reaching the moon Only occurs during a full moon Most lunar eclipses are partial