Transcript Consulting the Planetary Expert: You

Exploration of the Universe
For thousands of years humans have looked up at the sky in
wonder. As they observed they learned the sky was constant
and predictable. They learned to tell the time of day, the date,
the weather, their position and the occurrence of tides and
eclipses. Many other events were thought to depend on the
skies and astrologers were often employed to read the sky. This
type of prediction has nothing to do with science however. In
this same vein many different cultures have myths that are
associated with asterisms (distinctive star patterns such as the
Big Dipper) or constellations (an officially registered grouping of
stars such as Leo).
Today the sky is divided up into 88 regions, each associated
with a constellation (see constellation map) recognized by the
International Astronomical Union.
Hand out star map
Movement of Celestial Bodies
The Sun moves from east to west across the sky. The Sun
moves through the Zodiac constellations once per year. The
Moon moves from east to west across the sky but the moon rises
a bit earlier each day. The stars all revolve around Polaris (the
North Star), one complete revolution every 24 hours although
each star rises four minutes earlier each night. Planets seem to
move with the stars but after simple observations it can be seen
that planets wander through the sky. More careful observations
show that planets move eastward through the sky although about
once per year they experience retrograde motion where the
planet moves westward (backward) for a week or so.
Bring in telescope and observe sunspots
Set up astronomy nights.
Stargazing Activity
1. Observe the setting sun (or rising sun) from the same position
and record the time and location of the sunset.
2. Observe the moon from the same position at the same time
and record its location. Draw the shape of the moon.
3. Observe Jupiter from the same position at the same time and
record its location.
4. Observe Venus (in the morning!!) from the same position at the
same time and record its location.
Each set of observations (hopefully 10 at least) should be on
its own sheet of paper. Draw the landscape in front of you as
well.
Moon
Nov. 17 8:28 pm
Nov. 14 8:15 pm
Nov. 12 8:23 pm
Retrograde Motion
The word planets comes from the Greek word for wanderer. Stars
move very slowly in the sky relative to other stars but Planets
change their position quite quickly relative to stars. Outer planets
(Mars, Jupiter, Saturn, Uranus, Neptune) also display retrograde
motion. Planets move eastward in the night sky but once a year
for a month or two they move westward. This “reversal” is called
retrograde motion. Try the Retrograde Motion Activity.
Celestial Motion
The Greek philosopher Aristotle (500 BC) thought that all of the
planets and the Sun orbited Earth (geocentric model). All of these
objects were thought be contained in a sphere called the
firmament of fixed stars or celestial sphere. These ideas
dominated until the 1500’s but the retrograde motion could never
be explained adequately by geocentric model. Ptolemy (100 AD)
added epicycles (circles on circles) but still the geocentric model
didn’t fit the night sky observations.
Copernicus in the 1500’s proposed a heliocentric model which
had the planets, including Earth, orbiting the Sun. This allowed the
motion of all planets to fit the night sky observations almost
perfectly. Many people were against this model but slowly this
model was accepted. One piece of evidence which supported this
model was that Galileo found 4 moons orbiting Jupiter (with the
better telescopes he designed). He also found that Venus
displayed phases (just like the Moon).
Copernicus’s model was excellent but not perfect. The wonderful
observations of Brahe (late 1500’s) and the calculations of Kepler
showed that the planets actually move in ellipses around the Sun.
Finally Newton’s discovery of a theory of gravity explained why
the planets orbit the Sun and moons orbit planets.
Kelvin Scale for Temperature
1 degree change on the Kelvin Scale is equal to 1 degree change on the
Celsius Scale. 273 K is equal in temperature to 0 o C.
Consulting the Planetary Expert: You
Fill out the table on p. 446 (in your notebook) by consulting the
planetary data cards on p. 448 – 452. Saturn temp is -180 not -18
Make a list for each characteristic arranging them in order from
least to greatest. Use the Kelvin scale for temperature. Write down
the value of the characteristic as well.
State in months the orbital period of Mercury and Jupiter.
State in hours the rotation period of Saturn and Venus.
What is the diameter of Jupiter and Venus in km?
In km how far away from the Sun are Mars and Neptune?
Answer questions 1-7 p. 447 Some answers may need
information from p. 443 – 445 while other answers need
information from the planetary data cards.
On a legal sheet of paper show the relative distances from the Sun of
all of the planets (Pluto optional).
On a legal sheet of paper show the relative diameters of all the
planets, in no particular arrangement, by drawing circles of the proper
relative size. Colour the planets.
Modeling the Solar System p. 453 Outdoor Activity
Moon Phases
Draw one diagram of the Sun, Earth and the Moon showing how a
full Moon, half Moon, crescent Moon, gibbous Moon and new Moon
are produced. (Bonus, show a diagram of the Sun, Earth and a half
Venus.
Read p. 454 and make brief notes on Asteroids, Comets, Meteors
and Meteorites.
Chapter 13 Review p. 458-459 Questions 1-8