30. There are two classes
of planets in our solar
system: terrestrial and
jovian.
31. Terrestrial planets:
• The “earth-like” planets. “Terra” is another
name for Earth.
• Mercury, Venus, Earth & Mars.
• Terrestrial planets are small, “rocky”, high
density & orbit close to the sun.
• Someday, humanity may colonize the other
terrestrial planets for the benefit of
Humankind!
34. Earth: the
“goldilocks” planet
• Not too hot, not
too cold.
• The only planet
that can have
liquid water on
its surface.
• The only planet
we know that
has life.
35. Earth moves in two ways:
Rotation:
The Earth spinning on
its north-south axis.
The earth rotates at 150
per hour. After 24
hours, it has turned
3600 (one full turn)
36. Earth moves in two ways:
Revolution:
The Earth’s slightly elliptical
orbit around the Sun.
The Earth revolves about
10 per day. After 365 1/4
days, it has made a full
orbit around Sol.
Rotation: earth rotates on
its axis.
37. The 2 main evidence of earth’s
rotation:
1.Foucault's
pendulum
2.The Coriolis effect
40. Jovian planets
• The “Jupiter-like” planets. Jove was another
name for Jupiter.
• Jupiter, Saturn, Uranus, Neptune.
• They are very large, low density, made
completely of gases such as Hydrogen, helium,
methane & ammonia.
• They used to all be called: “the gas giants”
• Jupiter and Saturn are called the “gas giants”
• Uranus and Neptune are the “ice giants”
46. The sun
• The sun is middle aged main
sequence star. 4.6 billion years
old.
• The sun is powered by nuclear
fusion: Hydrogen atoms fusing
together.
47. stars
•All stars use nuclear fusion
to “power” themselves.
•Stars come in many colors:
red, yellow (our sun), white,
blue, (& probably brown)
56. the planets do NOT orbit the sun in perfect circles. The
planets revolve around the sun in elliptical orbits
(oval orbits), with sun being one of the foci.
57. This is a perfect circle!
This is an oval
This is an oval
Which is more “oval”?
66. the sun is very large but looks “tiny”
because it is far away.
67. Proof #2: that Earth
revolves around the
sun. The yearly change
in the zodiac.
68. The constellations of the zodiac
appear to move because Earth is
moving around the Sun!!!
69. Questions: name the two “R”
ways Earth moves.
Earth rotates and Earth
revolves.
70. Earth rotates
(spins) on its
axis.
The earth rotates
at 150 per hour.
After 24 hours, it
has turned 3600 .
Rotation gives
Earth night and
day
(one full turn)
71. Revolution:
*Earth revolves around the Sun in
slightly elliptical orbit.
* Earth revolves
about 10 per
day. After 365
1/4 days, it has
made a full orbit
around Sol.
74. The moon is a “satellite” of Earth because it
revolves around Earth.
Similarly, Earth is satellite of the Sun, because
Earth revolves around the SUN!
75. The moon takes 27 1/3 days to
complete one revolution around
Earth (sidereal month)
117. During the scienctific revolution (the
renaissance), Copernicus, Kepler, Galileo
& Newton developed the heliocentric
model: which showed that Earth is not the
center of the universe; Earth revolves
around the sun.
118. By the early 20th century, people
realized that our sun is only one of
billions of other stars in the milky way
galaxy!
124. How space distances are
measured:
Space distances are so
vast, new units of measure
had to be created to measure
space distances:
1.The light-year
2.Astronomical units (AU)
128. Big bang theory
• Developed by astronomers, who built
upon Hubble’s discoveries.
• the Universe formed from a single
infinitely dense particle called a
“singularity” that “exploded” 13.7
billion years ago.
• This explosion is why the universe is
expanding.
129. Two evidence of the big
bang:
1.***The “red shift” of light.
2.The cosmic microwave
background radiation.
