Earth%20and%20Space

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Earth and Space
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Our Solar System

• Our solar system is made up of
• Sun
• Eight planets
• Their moons
• Asteroids
• Comets
• Meteoroids

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Inner Planets

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

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Mercury

• Planet nearest the sun
• Second smallest planet
• Covered with craters
• Has no moons or rings
• About size of Earths moon

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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

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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).

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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

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Outer Planets

• The outer planets composed of gas are
• Jupiter
• Saturn
• Uranus
• Neptune

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Pluto

• Dwarf Planet
• Never visited by spacecraft
• Orbits very slowly

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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

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Comets

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

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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.

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Rotation versus Revolution

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

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Why Do We Have Seasons?

• The tilt of the Earths axis and the revolution
  around the Sun cause the Earth to have seasons.

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Combined Effects of Tilt and Revolution
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Earths Seasons - Year
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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.

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Instruments and technology used in astronomy
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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

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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

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Measurements in astronomy

• AU Astronomical unit 150 million km
• Distance between the Earth and the Sun
• Light year 9 500 billion km

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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"

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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.

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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.

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Solar system
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Galaxy

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

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ICW/Homework

• P.293 1,2,5,6,7
• P.294 10,11,18
• P.295 22,25