Astronomy

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Astronomy

• Earth Science R

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I. What is Astronomy?

• Astronomy is the study of the Universe.

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A. Astronomical Measures

• Long distances exist in space and are measured in
  
• Light Years.
• A light year is the distance that light travels
  in one year at a velocity of 186,000 mps or
  669,600,000 mph. Thats 5,865,696,000,000 miles
  in one year.
• One Light Year 1 Astronomical Unit (AU)

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B. Galaxies

• A galaxy is a system of stars (billions).
• There are three types.

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a. Spiral Galaxy
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www.galacticimages.com/catalog/images/m51exz.JPG
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http//www.adg.us/images/A20Barred20Spiral20Gal
axy20(1920x1200).jpg
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http//imgsrc.hubblesite.org/hu/db/1999/25/images/
a/formats/web.jpg
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The Milky Way from Earth
http//zebu.uoregon.edu/imamura/209/mar31/milkywa
y.gif
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The Milky Way from the Hubble Space Telescope
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Our position in the Milky Way
http//www.ncsu.edu/project/agronauts/images/milky
_way.jpg
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Our nearest neighbor
The Andromeda Galaxy http//en.wikipedia.org/wiki/
ImageM31_Lanoue.png
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b. Elliptical Galaxies
http//www.glyphweb.com/esky/_images/illustrations
/galaxy.gif
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c. Irregular Galaxies
http//www.godandscience.org/images/irregulargalax
yngc1705.jpg
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C. The Sun Our Closest Star

• Energy from the Sun drives all weather and water
  processes on Earth
• Temperature ranges from 6000 K at the surface to
  12,000,000 K at the center.
• The sun is composed of H He.
• Age is about 5 by and is expected to last another
  5 by.

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6. Sunspots

• Cooler gases result in dark spots called
  sunspots.
• Indicate that the sun does not rotate uniformly.
• Occur in 11 year cycles.
• Can alter Earths climate.
• Are actually areas of cooler gases.

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http//sohowww.nascom.nasa.gov/hotshots/2003_10_22
/sunspot.gif
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Checkpoint

• What is the fuel of the Sun?
• HYDROGEN

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Sample Questions

• What type of star is Polaris?
• RED GIANT
• Two stars of the same color are plotted on an H-R
  diagram. Star A is more luminous than Star B.
  Correctly explain the reason for this difference.
• Star A is larger than Star B

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More Sample Questions

• Name a star that is cooler and many times larger
  than Earths Sun.
• Betelguese
• Compared to other groups of stars, the group that
  has low luminosity and low temperatures are the
• Red Dwarfs

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The Electromagnetic Spectrum of Radiation
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Checkpoint

• What does a shift in wavelength toward the
  red-light end of the visible spectrum tell us
  about the universe?
• It is expanding
• Name a star whose surface temperature is closest
  to the temperature of the boundary between
  Earths mantle and Core.
• The Sun

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Checkpoint

• Which type of electromagnetic energy is more
  intense?
• ULTRAVIOLET
• or
• INFRARED

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II. The Solar System

• How did the planets form?
• ? Planets characteristics are based on their
  distances from the Sun.
• Terrestrial Planets are mostly rock
  where heat drove off ice gases.
• Jovian Planets are cooler and farther from
  the Sun therefore are mostly gas

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A. Terrestrial Planets

• MERCURY
• No Moons.
• Period of Revolution 88 days
• Period of Rotation 59 days
• Temps -180 to 430ºC
• No atmosphere.
• Difficult for us to see it being so close to the
  sun.
• The surface is Frozen in time like our Moon and
  Mars.

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Terrestrial Planets

• 2. VENUS
• No Moons.
• Period of Revolution 224.7 days
• Period of Rotation 243 days
• Temps consistently 400ºC
• The thickest atmosphere mostly CO2 and the air
  pressure is 90x that of Earth Greenhouse Effect
• Surface of great mystery.
• Extensive Volcanism.
• Day is longer than a year.
• Retrograde Motion

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Terrestrial Planets

• 3. EARTH
• One Moon.
• Period of Revolution 365.26 days
• Period of Rotation 24 hours
• LIFE is supported in the Ecosphere region around
  the Sun (from Venus to Mars)
• Oceans served as the breeding ground for life.
• Oceans allow us to live comfortably in moderation

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Terrestrial Planets

• 4. MARS
• Two Moons.
• Period of Revolution 687 days
• Period of Rotation 25 hours
• Temps reach 27 C
• LIFE??
• Polar Ice Caps

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B. Jovian Planets

• 5. JUPITER
• Sixteen Moons.
• Period of Revolution 11.86 yrs
• Period of Rotation 9 hr, 50 min
• A spinning top
• Great Red Spot

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Jovian Planets

• 6. SATURN
• Eighteen Moons.
• Period of Revolution 29.46 yrs
• Period of Rotation 10 hr, 14 min
• Rings of Ice

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Jovian Planets

• 7. URANUS
• Twenty-one Moons.
• Period of Revolution 84 yrs
• Period of Rotation 17 hr, 14 min
• Rotating on its side in Retrograde Motion.

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Jovian Planets

• 8. NEPTUNE
• Eight Moons.
• Period of Revolution 164.8 yrs
• Period of Rotation 16 hours
• Temps as low as -210 C
• Outermost planet in our solar system.
• Faint rings.
• Low energy from the sun leads to high winds.

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Dwarf Planets

• xx. PLUTO CO.
• Pluto itself has 2 moons.
• Period of Revolution 247.7 yrs
• Period of Rotation 6 days, 9 hrs
• Oblong orbit disqualifies it as a planet
• There are now eight similar objects beyond
  Neptune

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Checkpoint

• Which planets if placed in water would float?
• SATURN
• Correctly compare the size, density and
  composition of Neptune to Earth.
• Neptune is larger, more gaseous and less dense

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Checkpoint

• A major belt of asteroids is located between Mars
  and Jupiter. What is the average distance from
  the Sun to the Asteroids?
• 390 million km

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Space Travel the most significant advance in our
study of Astronomy
PLAY VIDEO
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III. Space Objects

• Asteroids Left over debris
• An asteroid belt comprised of thousands of small
  rocks circles the sun between Mars and Jupiter.
• The asteroid Hermes nearly hit Earth in 1936.
  It could happen

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B. Comets

• Large chunks of Ice moving at high velocities.
• Have orbits of High Eccentricity. See p 42.

http//images.google.com/imgres?imgurlhttp//star
ryskies.com/The_sky/events/meteors/comet.orbit.jpg
imgrefurlhttp//starryskies.com/The_sky/events/m
eteors/origin.htmlh345w410sz12hlenstart1
tbnidZcg5lacDm8BjnMtbnh105tbnw125prev/ima
ges3Fq3DComet2Borbit26svnum3D1026hl3Den26l
r3D
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C. Impact Events

• Craters are the result of impacts from
  extra-terrestrial objects.

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IV. Deep Space Phenomena

• Scientists believe the universe started with the
  big bang, 15 to 20 million years ago. Clouds of
  H He became galaxies and stars.

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A. Life of a Star

• Nebula gas and dust cloud
• Nuclear Fusion begins
• As the star ages, it becomes a red giant
• After the red giant collapses, it becomes a white
  dwarf.
• Increased gravity results in a neutron star.
• A neutron star may explode, resulting in a
  supernova.
• A new star called a pulsar may form briefly and
  the increased gravity causes it to collapse
  forming a black hole.

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Nebula
http//video.google.com/videoplay?docid-169733958
9356701058qstellarlife
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Red Giant as seen from Hubble
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White dwarf
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Supernova
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Black Holes
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Checkpoint

• Stars will undergo evolutionary changes over
  millions of years. Which sequence of events
  shows the predicted life of Earths Sun?
• Yellow Star?Red Giant?Black Hole
• Yellow Star?Supernova?Black Hole
• Yellow Star?Red Giant?White Dwarf
• Yellow Star?Supernova?Black Dwarf

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B. Apparent Star Motions

• Stars appear to move in different paths across
  the night sky, just like the sun appears to move
  across the sky throughout the course of one day.
• Circumpolar Stars that can be seen throughout
  the year, appear to circulate around Polaris.
• Ecliptic Stars that can only be seen during
  certain months of the year. They are eclipsed
  by the Sun.

PLAY VIDEO
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C. The Constellations
Constellations are patterns of stars in the sky.
The zodiac of the month is eclipsed by the Sun.
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Orion, A Winter Constellation
PLAY VIDEO
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Phases of the Moon
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Waxing Crescent
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Phases of the Moon
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First Quarter
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Phases of the Moon
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Waxing Gibbous
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Phases of the Moon
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Full Moon
Once in a Blue Moon?
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Phases of the Moon
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Waning Gibbous
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Phases of the Moon
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Third (Last) Quarter
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Phases of the Moon
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Waning Crescent