Solar system notes

1. III. The Solar System
A. Solar System Inventory
1. Planets
a. Terrestrial Planets (Earth-like)
- The First Four Planets: Mercury,
Venus Earth and Mars
- All are found within 1.5au of the
Sun and have similar chemical
properties.
- All are low-mass, with
atmospheres and rocky surfaces.
- Have relatively long rotations (for
their size) & short revolutions.
Similarities

2. 1. Terrestrial Planets Continued..
Atmospheres – Mercury has almost none
Venus has the Densest
Earth is the only planet with Oxygen
Mars has a thin atmosphere of CO
2
.
Rotations – Earth and Mars both take roughly 24 hours
Venus and Mercury take months to complete
one rotation. In fact Venus rotates very slowly
in the opposite direction of all other planets.
Moons – Earth and Mars both have moons
Mercury and Venus have none
Distances from the Sun:
Mercury: .4au Earth: 1au
Venus: .72au Mars: 1.5au

3. b. Jovian Planets: (Jupiter-like)
- The Last Four Planets: Jupiter, Saturn, Uranus,
Neptune
- VERY widely spaced out (5au to 40au away)
- All are high mass, mostly consisting of hydrogen &
helium gases, with no rocky surface.
- Have relatively short rotations and long revolutions.
- All have large systems of rings and moons
Distances from the Sun:
Jupiter: 5 au Uranus: 20au
Saturn: 10au Neptune: 30au

4. 2. Jovian Planets Continued..
Atmospheres – Jupiter and Saturn are mostly Helium
Uranus and Neptune have large amounts of
methane.
Rotations – All have rotations that are shorter then one
earth day, but Uranus actually rotates sideways.
Moons – Have many moons made mostly of ice and
small amounts of rock.
- Jupiter: 32+ moons, plus 4 of the largest
- Saturn: Many moons. Largest is Titan
- Uranus: The moons orbit at the same inclination
as the planet rotates.

5. Why no Pluto?
Recently scientists have discovered many objects of
similar size and composition to Pluto (some even
larger). So they came up with a definition for the
word planet:
a. Orbits a star
b. Has sufficient gravity to pull itself into a spherical
shape.
c. Has cleared the area of its orbit of other debris
d. Is not undergoing nuclear fusion.
Pluto has been therefore defined as a dwarf planet.

6. c. Terrestial Planets in Detail
1. Mercury
A. 0.4au from the sun

B. Temperature extremes from
700 K during the day and 100

K at night.

C. The smallest planet (in both
diameter and mass)
D. The high daytime temperature and low gravity
means that Mercury cannot hold onto any appreciable
atmosphere.
E. The interior of Mercury is a large Iorn Core. This
causes it to have a weak (100 times less then earth)
magnetic feild.

7. c. Terrestial Planets in Detail
2. Venus
A. About 0.7au from the sun
B. Has the hottest average surface
temperature, 730 K.

C. Very close in mass to the Earth.
D. Has an atmosphere of 96.5%
Carbon Dioxide. This has lead to

a runaway greenouse effect
which is why it is so much hotter
then any other planet.
E. Venus has no known magnetic field.

8. c. Terrestial Planets in Detail
3. Mars
A. Roughly 1.5au from the sun

B. Only 1/3 the mass of the earth
C. Average temperature on Mars
is about 50 K cooler then the
Earth.
D. Has an atmosphere of 95.6%
Carbon Dioxide, but it is
13,000 times thinner then

Venus
E. No magnetic field has ever been detected on Mars.
This is likely because its core has cooled and become
soild or because it does not contain enough metalic
material.

9. d. The jovian planets
1. Jupiter
A. About 5au from the sun
B. By far the most massive of all
the planets.
C. More then 28 moons discovered
so far. Some are larger then the
planet Mercury.
D. Known for it's distinct banding of
clouds at different latitudes.
E. Has a very thin system of rings.

10. d. The jovian planets
1. Saturn
A. About 10au from the sun
B. Second most massive planet.
C. Also has a vast system of moons

D. Does not have many distinct
bands in it's clouds..

E. best known for it's spectacular
ring system.

11. d. The jovian planets
1. Uranus
A. About 20au from the sun
B. Contains no visible cloud
banding.

C. Also has a vast system of moons

D. Has a small system of rings.

E. best known for rotating 98
o

compared to the ecliptic.
F. This gives Uranus the most extreme seasons of any
planet in the solar system

12. d. The jovian planets
1. Neptune
A. About 30au from the sun
B. Known for having the fastest
winds in the solar system. Clocked
at over 2000 km/hr..

C. Also has a vast system of moons

D. Does not have many distinct
bands in it's clouds..

E. The only outer planet to have an
interior source of heat. It radiates 2.7 times
more heat then it receives from the sun.

13. 2. Solar System Debris
a. Asteroids: Masses of rocky material that is not part
of a planet or moon.
- Most are found 2.1au to 3.3au from the sun.
Between the orbits of Mars and Jupiter. This is
known as the Asteroid Belt.
- In addition to Main belt asteroids
there are two “packs” of
asteroids that share Jupiter's
orbit. 60
o
ahead and behind
the planet. These are
known as the Trojan asteroids.

14. 2. Solar System Debris
a. Comets: Masses of icy material that travel from the
outermost reaches of the solar system to very close
to the sun. VERY elliptical orbits.
- Made mostly of frozen water, ammonia and
some rocky material. Think of a dirty snowball.
This is known as the nucleus of the comet.
- When the comet approaches the sun
many of these materials vaporize. The
cloud of vapor around the nucleus is
called the coma.
- The gas and dust trailing the comet is
called the tail. The tail always points
away from the sun.

15. Anatomy of a comet
Tail
Nucleus
Coma