Download The Origin of the Solar System

Planetary Orbits
Mercury
Venus
Earth
All planets in almost
circular (elliptical)
orbits around the
sun, in approx. the
same plane
(ecliptic).
Sense of revolution:
counter-clockwise
Sense of rotation:
counter-clockwise
(with exception of
Venus, Uranus)
(Distances and times reproduced to scale)
Orbits generally
inclined by no
more than 3.4o
Exceptions:
Mercury (7o)
The Solar Nebula
Hypothesis
Basis of modern theory
of planet formation.
Planets form at the
same time from the
same cloud as the star.
Planet formation sites
observed today as dust
disks of T Tauri stars.
Sun and our solar system
formed ~ 5 billion years ago.
Two Kinds of Planets
Planets of our solar system can be divided
into two very different kinds:
Terrestrial (earthlike) planets:
Mercury, Venus, Earth, Mars
Jovian (Jupiter-like) planets:
Jupiter, Saturn, Uranus, Neptune
Space Debris
In addition to planets, small bodies orbit the sun:
Asteroids, comets, meteoroids
Sample of asteroids
Terrestrial
Planets
Four inner planets
of the solar system
Relatively small in
size and mass (Earth
is the largest and
most massive)
Rocky surfaces
Weak or no present
atmospheres
Few or no moons
No ring system
Surface of
Venus can not
be seen
directly from
Earth because
of its dense
cloud cover.
Mercury
Closest planet to the
Sun but not the hottest.
No atmosphere
No moons
It is smaller than a
couple of moons
however it is more
massive since it is made
mostly of metals.
Notable space missions:
Mariner 10
MESSENGER
Venus
Clouds of SO2
Similar in size and mass
to the Earth
No moons
Dense atmosphere
containing mostly CO2
leading to a massive
greenhouse effect.
Hottest planet in the solar
system.
Rotates backwards and
day is about 250 Earth
days
Visual wavelength image
Venus
Rocky surface is covered
with volcanoes and
craters.
Volcanic activity is
currently a mystery. In
March 2014 infrared
flashes were detected
from the surface
indicating outgassing.
Notable space missions:
-Venera (Russian)
-Mariner (US)
-Venus Express (ESA)
Radar imaging of surface
Surface of Venus from Venera 9
First image of the surface of another planet
Surface craters
Maat Mons
Largest volcano
on Venus
Mars
Olympus Mons
Polar caps of CO2
and water ice.
Half the radius of the
Earth but equal in land
surface area.
Two “moons”.
Weak atmosphere
containing mostly CO2
and weak amounts of
methane and ammonia.
Similar rotational period
(24hr 37m) and axial tilt
to Earth (25.2°)
Surface is most similar to
Earth
Host to many current
space science missions
Valles Marineris
The Jovian Planets
Complex satellite systems
Thick atmospheres
Much larger in mass
and size than
terrestrial planets
Much lower
average density
All have rings
(not only Saturn!)
Mostly gas; no
solid surface
Jupiter
Largest planet
No solid surface
Atmosphere is primarily
hydrogen and helium with trace
amounts of methane, ammonia
and hydrogen sulfide.
Faint system of rings
Over 60 moons
Gigantic magnetic field causes
auroras at the poles.
Great Red Spot – giant storm
Large gravitational influence as
a as solar system “vacuum
cleaner”
Visited by Pioneers, Voyagers,
Galilieo spacecraft.
Galilean satellites
Io
Europa
Ganymede
Callisto
Jupiter from Voyager 1 - https://www.youtube.com/watch?v=9nf9nBtd2dM
Jupiter in Motion - https://youtu.be/MyNkyL2mpmM?t=17m35s
Jupiter Cloud Motion - https://www.youtube.com/watch?v=RdIfnymd9Aw
Saturn
Very similar in
composition to
Jupiter.
Substantial ring
system
Largest satellite
system with
over 150
members.
Titan is the
largest moon.
Sunlight reflected off liquid bodies on Titan
Huygens Descent to Titan - https://youtu.be/9L471ct7YDo?t=37s
Uranus
Gas giant but
contains a significant
amount of ice.
Bland atmosphere
due to no internal
heat source.
As a result, high wind
speed smooth out the
atmosphere
Color is mainly due to
methane
Weak ring system
and around 27
satellites
Visited only by
Voyager 2
Neptune
Gas giant but
contains a significant
amount of ice.
Bland atmosphere
due to no internal
heat source.
As a result, high wind
speed smooth out the
atmosphere
Color is mainly due to
methane
Weak ring system
and around 14
satellites
Visited only by
Voyager 2