Download Unit E - Topic 1.0 Notes

Space Exploration
1.1 Early Views about the Cosmos
Celestial objects have fascinated humans
throughout history. These include:
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The sun
The moon
The stars
Constellations
Planets
Meteors
Falling stars
Northern lights
Celestial events of particular interest to humans
were / are:
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Solar and lunar eclipses
Meteor showers
Aurora borealis
Comets
The Greeks were the first
to explain how the universe
worked in a logical, systematic manner.
Models of Planetary Motion
1. Geocentric model: Aristotle 2000 years
ago
– The earth is the center of the universe
2. Heliocentric model: Copernicus about
1500 AD
- The sun is the center of the universe and all
other planets orbit around it.
Models of Planetary Motion
Geocentric Model
Heliocentric Model
Proposed by / when:
Aristotle – over 2000 years ago
Copernicus – 1530 AD
Description:
Earth is center of universe
Sun is center of universe
Supported by:
Euclidian and Pythagorean
math used to calculate the size
of the spheres
Telescopes allowed
scientists to see mountains
on the moon and the rings
of Saturn
What wasn’t explained:
Movement of the planets was
irregular
Planetary motion didn’t
follow a circular pathway
What next:
Replaced with the heliocentric
model
Updated to account for
elliptical pathways of the
planets
Geocentric Model - Aristotle
Heliocentric Model - Copernicus
Aristotle’s Model
(Geocentric)
Assisted by Pythagoras
and Euclid
Copernicus’ Model
(Heliocentric)
Confirmed by Galileo and
Kepler
Revisions to the Heliocentric Model
• Galileo Galilei – saw mountains on the moon
with a telescope and confirmed Copernicus’
ideas
• Tycho Brahe – observed and recorded the
movement of the planets, confirmed a circular
orbit was not likely
• Johannes Kepler – proposed the planets
followed elliptical orbits around the sun
Cosmological Events
• Solstice means “sun” “stop” and represent the
shortest and longest periods of daylight.
• June 21 – the summer solstice is the longest
day of the year
• Dec 21 – the winter solstice is the shortest day
of the year
Equinox
• Means “equal” “night” and represents periods
of equal day and night.
• Vernal Equinox - March 21 – spring equinox
• Autumnal Equinox - Sept 22 – fall equinox
Ancient peoples celebrated the solstice and
equinox occasions by creating large structures
Chichen Itza
Pyramids at Giza
Stonehenge
Medicine Wheel
Our solar system – size and scale
• http://www.youtube.com/watch?v=D1iK2p8q
wdY
• http://www.youtube.com/watch?v=z6yHKE9d
g0g&feature=related
• http://www.youtube.com/watch?v=mtKNH2Y
2OJM&feature=related
Astronomy tools
• Sundial: have been used for more than
7000 years to measure the passage of
time - based on the sun's position in
the sky
• Merkhet: invented by the Ancient
Egyptians to chart astronomical
positions and predict the movement
of stars
• Quadrant: Invented in the 2nd century
AD by the Egyptian astronomers to
measure a star's height above the
horizon
• Astrolabe: Used by Arabian
astronomers to make accurate charts
of star positions
• Cross-staff: invented by Levi ben
Gurson to measure the angle between
the Moon and any given star
• Early Telescope (late 16th century):
invented in the late 16th century and
it allowed astronomers such as Galileo
to discover details about Earth's closet
planetary neighbors and the relative
size and distance of what laid beyond
Earth
• Optical/Radio Telescopes and Space-Based
Telescopes: operating from Earth, satellites
orbiting around Earth and space-based
telescopes have reveals the immensity of objects
in space and distances across the universe. Also
have discovered that our sun is simply one in the
corner of our galaxy that is among of billions of
other galaxies.
Measuring Distance and Time in Space
• Astronomical Units (AU) - Used for….measuring
"local distances", inside our solar system
1 AU = average distance from the center of Earth
to the center of the Sun = 149 599 000 km
Used when…describing positions of the planets
relative to the Sun
less than 1 = closer to the sun than Earth
greater than 1 = further from the sun than Earth
The furthest planet (Pluto) from the sun is 39.5
AU away
• Light Years
Used for….when the vast distances beyond the
solar system, out to the stars and galaxies are
too great for astronomical units.
It equals the distance that light travels in one
year
Speed of light is…300 000 km/s
Light travels 9.5 trillion km in 1 year
The nearest star (after the sun) is 4 light years
away.
Looking In the Past
The light we seen has taken time to get to us therefore
the images we see are from the past. The time delay for
the images coming from the following places is…
Light travelling from…
The moon
The sun
Pluto
Stars in the center
of the galaxy
Light captured by the
Hubble light telescope
Time Delay
1 second
8 minutes
5 hours
25 000 years
13 billion years
Do Check and Reflect p. 383, # 1-8