Earth Science - Astronomy

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Earth Science - Astronomy
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What is Astronomy?

• Astronomy is the study of anything we see in the
  sky, and beyond
• Overlaps with physics, chemistry, geology, and
  other sciences

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The Scientific Method in Astronomy

• Astronomy is one of the most difficult sciences
  to do, because we cant do very many things in a
  lab
• We have to combine our observations with our
  understanding of other sciences to make good
  predictions
• Sometimes, our lab is a computer

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Astrology

• Astrology - the belief that the stars and planets
  affect your life
• Despite the ology, its not a science!
• Gravity of other planets is not as strong as the
  gravity of your obstetrician!
• Does not use the scientific method
• Its complete poppycock

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Observing the Universe

• Astronomy began with people observing their
  surroundings
• What did the sky look like when herds moved?
  When a season changed?
• When was it good to plant?
• Planets, sun, moon, and stars all seemed to move
  independently

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What have you Observed?

• An incomplete list
• Moon
• Planets (Venus, Mercury, Mars, Jupiter, Saturn)
• Stars
• Meteors (shooting stars)
• Aurora
• Comets

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Whats Out There, Anyway?

• Atmospheric phenomena
• Solar System
• Sun and planets comets, asteroids, etc.
• Milky Way
• Our galaxy
• Extra-galactic
• Other galaxies
• Some objects like our galaxy
• Some completely different phenomena
• Things between galaxies

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Atmospheric phenomena

• Auroras
• Meteor Showers

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Solar System Objects and Phenomena

• The Sun
• Eclipses
• Planets Moons
• Asteroids
• Comets

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Galactic Objects and Phenomena

• Stars star clusters
• Nebulas
• Supernova Remnants
• Dead Stars
• White Dwarfs
• Neutron Stars
• Black Holes
• Dark Matter

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Extra-Galactic Objects and Phenomena

• Other Galaxies
• Galaxy Clusters
• Super Clusters
• Dark Matter
• Dark Energy

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Neighborhood Tour - Our Solar System
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The Solar System

• Condensed from Solar nebula about five billion
  years ago
• Contains Sun, planets, asteroids, comets, and
  dust

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Terrestrial verses Jovian Planets

• Terrestrial Planets Include
• Mercury, Venus, Earth and Mars
• Jovian Planets Include
• Jupiter, Saturn, Uranus Neptune
• Also Interesting Jovian moons
• Not sure what to do with them
• Pluto/Charon
• Xena

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Sol (our sun)
SOHO/Extreme Ultraviolet Imaging Telescope (EIT)
consortium
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The Solar System
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Terrestrial Planets

• Small and rocky, composed of Oxygen, Silicon,
  Aluminum, Calcium, Iron, and Magnesium
• Mercury
• Venus
• Earth
• Mars

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Mercury

• Mercury has a lunar-like geology.

Caloris Basin
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Mercury

• Mercury is almost tidally locked, like the Moon.

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Venus

• Venus surface has only been revealed in the past
  10 years.

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Venus

• The surface of Venus is like the surface of hell.

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Venus

• Venus has a young, basaltic surface.

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You Probably Know This One
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Mars

• Mars has the most Earth-like geology.

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Mars

• Mars has a thin atmosphere of CO2.

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Mars

• Familiar geologic features/processes

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Mars

• Familiar geologic features/processes

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Mars

• Mars geologic history was once warmer and wetter
  than now.

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The Real Face of Mars
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Mars from Pathfinder
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Sojourner
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Olympus Mons
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Mars Polar Caps
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Martian Meteorite
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Martian Fossils ?
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Deimos and Phobos
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Jovian Planets

• Large, gaseous, composed mainly of hydrogen and
  helium
• Jupiter
• Saturn
• Uranus
• Neptune

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Jupiter

• Jupiters geologic features are all atmospheric.

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Moons of Jupiter

• Io is the most active body in the Solar System.

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Moons of Jupiter

• All these worlds are yours except Europa

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Moons of Jupiter

• Ganymede and Callisto are two of the larger
  bodies in the Solar System.

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Saturn

• Saturn is the furthest out of the historical
  planets.

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Saturns moons
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First ever color picture of Titans surface
January 14, 2005
Water and hydrocarbon ice
ESA/NASA/Univ. of Arizona
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Uranus moons

• Uranus orbits the Sun on its side.

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Neptune moons
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Pluto Charon
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Units for MeasuringAstronomical Distances

• Astronomical Units (AU)
• Defined as the distance from the Sun to the Earth
• About 1.496x1011 m (about 150 million km)
• Light-years
• Defined as the distance light travels in one year
• About 9.46x1015 m
• Parsecs
• Derived from the way stars appear to shift
  slightly in the sky as the Earth orbits the Sun
• Equal to about 3.26 light-years

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How Big Is It?

• Our Earth
• 12,756 km across
• Earth to the Moon
• 384,400 km
• Earth to the Sun
• 150 million km
• 1 AU
• 500 light-seconds

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How Big Is It?, cont.

• Sun to Jupiter
• 5.2 AU
• Sun to Pluto
• Between 30 and 49 AU
• Oort Cloud
• Theoretical, unobserved edge of the Solar System
• Out to about 50,000 AU ( 0.79 light-year)

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How Big Is It?, cont.

• Nearest star
• 4.2 light-years away
• Our Galaxy
• 100,000 light-years across
• To the nearest large galaxy
• 2.5 million light-years away

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How Big Is It?, cont.

• Virgo Cluster of Galaxies
• Nearest cluster of galaxies to us
• About 50 million light-years (debated)
• Quasar 3C 273
• One of the nearest and brightest quasars
• About 2 billion light-years
• Edge of the observable Universe
• About 13.7 billion light-years away

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Light travel times

• Across earth 0.04 seconds
• From moon 1.3 seconds
• From sun 8 minutes
• From Neptune 4 hours

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Light travel times

• From nearest star 4 years
• From galactic center 25,000 years
• From Andromeda galaxy 2 million years
• From hot early universe 14 billion years