Chapter 9 - Venus Chapter 10 - Mars Chapter 11 - Jupiter With Doctor Bones aka Don R. Mueller, Ph.D.

1. Astonishing Astronomy 101
With Doctor Bones (Don R. Mueller, Ph.D.)
Educator
Entertainer
J
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Scientist
Science
Explorer

2. Chapter 9 - Venus
Earth’s Sister Planet

3. Venus – Not so twin-like after all.
• Venus, called Earth’s “twin”
is only slightly smaller than
the Earth, but that’s where
the resemblance ends.
• Thick clouds completely
obscure the surface.
• It rotates very slowly (once
in 243 Earth days), and in
the opposite direction to
the rest of the planets of
the solar system.
• The surface is hot, hot, hot!

4. The Venusian Atmosphere
• The atmosphere of Venus is quite
different from that of Earth:
• 100 times more massive.
• Venus has an atmospheric
pressure of about 90 times
that of Earth:
Choked by 96.5% carbon dioxide,
thick clouds of sulfuric acid and
trace amounts of water vapor.
• The planet likely underwent a
runaway greenhouse effect.

5. Images from Venus
• The Russian Venera spacecraft
have visited the surface of
Venus.
• Surface temperatures: 750 K
hot enough to melt lead.
• Discovered volcanic rocks.
• The spacecraft only lasted
about an hour due to the
extreme temperatures and
pressure.
• More recent spacecraft have
mapped the surface of Venus
from orbit.

6. The Surface of Venus
• Venus has both highlands
and lowlands.
• Surface features: named
for prominent women in
history and mythology.
• Venus is less mountainous
than Earth, with more
rolling plains.
• Volcanic peaks are present
in the highlands.

7. Radar map of Venus
• The surface of Venus
appears to be
relatively young.
• Plenty of volcanic
activity resurfaces
the planet rapidly.
• With few impact
craters, due both to
the thick atmosphere
and volcanic activity.

8. Interesting features of the surface of Venus

9. The Orbit and Rotation of Venus
Venus completes an orbit of
the Sun every ~ 225 days.
Of the planets, Venus spins
about its axis the slowest:
 About 243 Earth days to
complete one rotation.
 The slow rotation creates
almost no magnetic field.
Daily Rotation

10. The Role of Sunlight
• A planet’s distance from the
Sun determines how much
sunlight it receives.
• Venus receives ¼ of the
energy per square meter that
Mercury does.
• Planets in eccentric orbits
receive varying amounts of
sunlight.
• The axial tilt of a planet
determines its seasons.
• Sunlight warms and the
atmosphere has an impact too:
• Venus’s atmosphere warms the
surface to 750 K, but it would be
very warm even without the CO2.
• Mercury is closer to the Sun, but
still cooler than Venus.
• The Moon is cooler than the Earth,
even though they are at the same
distance from the Sun.
• Sunlight also determines the
makeup of the planets:
– Inner planets are rock and
iron bodies.
– Outer planets are gaseous.

11. Chapter 10 - Mars
The Red Planet

12. Mars
• Mars is the most explored
planet (aside from Earth)
in the Solar System.
• Mariner 4 provided the
first close-up image (1965).
• ESA’s Mars Express (2003).
• Global Surveyor
• Odyssey
• Mars Reconnaissance
Orbiter
• And more to follow:

13. Major Features of Mars
Mars: The home to amazing sites:
• Valles Marineris
(1) Named for Mariner 4
(2) A canyon that stretches
across the face of the globe.
(3) As wide as the United States.
• Olympus Mons
(1) Tallest mountain in the solar
system (26 km tall.)
(2) Probably no older than 250
million years.

14. Map of Mars
• The Tharsis bulge may have been caused by an upwelling of hot
material from the interior of the planet, creating volcanoes in the
region (including Olympus Mons) and perhaps also Valles Marineris.

15. Olympus Mons
• Tallest mountain in the
Solar System.
• Extends above the bulk
of the atmosphere of
Mars.
• A volcano around 250
million years old.
• The largest known
volcano in the solar
system is located on
Mars.

16. Dune Fields
• Deserts ring Mars at
its mid-latitudes.
• Winds blow surface
material into dunes,
similar to those
found on Earth.

17. Ice Caps of Mars
• The polar ice caps of Mars
are composed mostly of
water ice covered by a
relatively thin layer of
carbon dioxide.
• Growing and shrinking
seasonally.
• Mars has an axial tilt
similar to that of Earth:
produces seasons similar
to those found on Earth.
• Southern winters are more
extreme than the north, as
Mars is farthest from the
sun during this period.
Please insert
figure 40.6 A

18. Water on Mars? Probably flowed freely long ago.
• Many scientists think that Mars
was once warmer and wetter
than it is today.
• Surface features support this:
– Dry riverbeds.
– Splash craters (craters that
form from impacts on damp
soil).
– Gullies in crater walls.
• Mars must have had a warmer
and denser atmosphere in the
past to support liquid water on
its surface.

19. Evidence for Water?

20. Splash Craters

21. Gullies

22. Where’s the water? Where did the water go?
• Some water may be
trapped just below the
surface as permafrost.
• Water may be locked in
mineral compounds.
• Most water probably
escaped to space:
(1) Evaporated
(2) Dissociated by photons.

23. The Surface of Mars
• A dry, dusty place.
• Covered with rocks
ranging from pebbles to
boulders.
• Evidence for flowing
water, rivers and salty
oceans.

24. The Martian Atmosphere
• The Martian atmosphere
is very different from
Earth’s.
95% CO2 and 3% N2
Surface pressure is very low.
Clouds of water ice and
carbon dioxide ice float
through the sky.
No rainfall, but it sometimes
snows dry ice crystals.
Temperatures range from
above freezing to 180 K.
• Martian winds, though gentle, can
carry dust far into the atmosphere.
– These dust storms sometimes
obscure much of the surface.
• No erosion.

25. The Moons of Mars: Phobos and Deimos
Mars has two moons: Phobos and Deimos.
Both are small (20 km across): likely captured asteroids.

26. Chapter 11 - Jupiter
The Gas Giant

27. Jupiter
Jupiter
5 AU from the Sun.
11 times the Earth’s
diameter.
300 times the Earth’s
mass.
Earth

28. Jupiter’s
Appearance
• Parallel bands of clouds:
Dark belts and Light zones.
• Its atmosphere is 90% H2 and
10% He, with traces of methane,
ammonia and water.
• The outer atmosphere has a
temperature of 160 K.
• Rotates once every 9.9 hours.
• Visibly flattened.
Belts Zones
Great Red Spot

29. The Interior of a Gas Giant
Please insert figure 43.3

30. The Interior of Jupiter
• Jupiter’s average density is 1.3 kg/liter.
• Jupiter is in hydrostatic equilibrium:
Gravity pulls inward and the interior pressure pushes out.
The two forces are balanced.
• No solid or liquid surface:
The pressure is high enough to create liquid metallic
hydrogen, a fluid that acts like a metal.
Jupiter probably has a molten rocky core: larger than the
Earth itself.
• Jupiter generates more heat than it receives from the Sun.

31. Equatorial Bulge
• Jovian planets rotate
much faster than
terrestrial planets.
• From the principle of
conservation of
angular momentum.
• Faster rotational
speeds make the
outer planets much
wider at the equator.
The so-called
equatorial bulge.
Earth Jupiter

32. Jupiter’s rapid rotation creates strong Coriolis forces and high winds.

33. Jupiter’s
High Winds
Equator

34. The Great Red Spot
• On Jupiter, these wind
shears give rise to
enormous vortices or
storms, seen as white,
brown or red ovals in
its clouds.
• The Great Red Spot is
one such vortex:
• The longest lasting
storm in the solar
system.
• The Great Red Spot is a storm that
has lasted for at least 300 years!

35. Magnetic Fields
• The liquid metallic
hydrogen in Jupiter can
carry electrical currents,
similar to the liquid core
of the Earth.
• These currents generate
very large magnetic fields.
Jupiter’s magnetic field is
20,000 times as strong as
Earth’s.
Jupiter experiences auroras.

36. The Galilean Satellites
• The four largest moons of Jupiter are called the Galilean
satellites, in honor of their discoverer, Galileo.
• They appear as pinpoints of light through small
telescopes or binoculars.
• An excellent target for amateur astronomers.

37. The Galilean Satellites
• The Galilean satellites would be considered planets if
they orbited the Sun independent of Jupiter.
• Temperatures range from 110-130 K.
Io
Europa

38. The Galilean Satellites
CallistoGanymede

39. Io is one of the most exotic places in the solar system
• Io is closest to Jupiter and has a
very active interior.
• Looks like a giant spherical pizza
covered with melted cheese and
splotches of tomato and ripe olives.
Io is the most volcanically active
body in the Solar System.
• The third largest of
Jupiter's moons.
• Tidal forces cause
Io's surface to
bulge in and out by
as much as 100
meters (330 feet).

40. Europa is covered with cracks: Reddish mineral-rich
water seeps out to make these cracks visible.

41. Tidal forces stretch Europa, leading to tidal heating, which
in turn melts the surface ice resulting in liquid water.
Metallic Core Ice Cover
Liquid
Ocean
Water Layer
Rocky
Interior

42. Ganymede and Callisto Ganymede
• Metal core, covered by
a rocky layer and a 800
km deep ocean.
• Surface is mostly ice,
pockmarked by craters.
• Younger grooved
terrain from tectonic
activity.
Callisto
• Less differentiated
than other moons.
• Mix of ice and rock
in its interior.
• Thin icy crust.