Intro to Planetary Astronomy Quest #4
Saturn's Shepherd Moons
- Pan (Encke gap) - Daphnis (Keeler gap) - Atlas (A Ring) - Prometheus (F Ring) - Pandora (F Ring)
Spacecrafts that have flown by Jupiter
- Pioneer 10 & 11 (had a plaque attached to look for ET) - Galileo Spacecraft - Juno Spacecraft
Dwarf planets w/ moons
- Pluto: 5 - Eris: 1 - Haumea: 2
Saturn's disappearing rings
- a phenomenon caused by the planet's rotation on an axis (Its rings are oriented edge on as viewed from Earth every 15 years) - makes rings look "invisible" in all but the very largest telescopes
Saturn's Magnetic Field
- almost perfectly aligned with the planet's rotation - far weaker than Jupiter's
Giant Red Spot on Jupiter
- an upwelling of material from Jupiter's interior that is a long-lived enormous storm system - 20,000 km in diameter - Smaller & less red than it used to be - appearing consistently the last 300 years
Besides discovering Uranus, William Hershel also....
- built telescopes - discovered 4 moons - discovered infrared radiation
Composition of Ice Giants
- contain larger amounts of water and other ices than the gas giants - lesser amounts of H and He than gas giants
Clouds on Saturn
- less activity than Jupiter - less color than Jupiter
Atmosphere of Jupiter
- mostly hydrogen and helium - lots of molecular hydrogen in outer atmosphere (goes from gas to liquid to liquid metallic hydrogen to ice to rock the deeper you go)
Atmospheric Gases/Clouds by Elevation (Jupiter)
-100 km: H2O -50 km: NH4HS -25 km: NH3 150 km: N2H4
Average Temperature on Uranus
-195 degrees C
Average Temperature on Neptune
-200 degrees C
Atmospheric Gases/Clouds by Elevation (Saturn)
-275 km: H2O -175 km: NH4HS -100 km: NH3 150 km: P2H4
Saturn's Average Density
0.7 g/cm^3
The three giant planets than can be seen w/ the unaided eye
1. Jupiter 2. Saturn 3. Uranus (difficult to see)
Zones of Jupiter
light-colored bands in Jupiter's cloud cover
Neptune has clouds in its atmosphere made up of.....
methane ice crystals
Uranus color
pale green
Jupiter's Magnetic Field
- 10 times stronger than earth due to the liquid metallic region - leads to aurora like earth
Galileo and Saturn's Rings
- 1610: observed 2 objects near Saturn - Thought to be "moons" but these "moons" didn't orbit Saturn - 1612: the "moons" disappeared
Jupiter's Rings
- Discovered by Voyager 1 - they are very dim, but still exist - Likely formed from debris of a broken moon
Giant planets in general are made up of....
- Gases (Hydrogen, Helium) - Ices (Nitrogen, Carbon, Oxygen, etc.) - Rocks (Iron, Magnesium, Silicates, etc.)
Jupiter's Galilean moons
- IO - Europa - Ganymede - Callisto
Moons of the outer solar system
- Jupiter: 95 - Saturn: 146 - Uranus: 27 - Neptune: 14
Moons in the inner solar system
- Mercury: 0 - Venus: 0 - Earth: 1 - Mars: 2
Composition of Saturn's Interior
- Molecular hydrogen - Liquid hydrogen - Metallic liquid hydrogen - Ice - Rock
Orbit of Saturn's ring particles
- Obey Kepler's laws - Closer particles orbit faster - Motions of particles in opposite directions cancel out
Diameter of Neptune
49,500 km
Clouds in Jupiter's Atmosphere
- Lots of different colors (tan, yellow, red, white, etc.) - Differ based on elevation
Mass of Neptune
1.024 × 10^26 kg
Uranus's Average Density
1.3 g/cm^3
Jupiter's Average Density
1.33 g/cm^3
Neptune's Average Density
1.6 g/cm^3
Mass of Jupiter
1.9 x10^27 kg
Saturn's Rotation Period
10.7 Hours
Jupiter's Period of Orbit
11.86 Years
Diameter of Saturn
120,540 km
Neptune's Number of Moons
14
Diameter of Jupiter
143,000 km
Saturn's Number of Moons
146 (82 known?)
Neptune's Rotation Period
16.1 Hours
Neptune's Period of Orbit
164.8 Years
Uranus's Rotation Period
17.2 Hours
Uranus discovery
1781 by William Hershel - first unknown planet to be discovered - called the "Georgian Star" because of King George III
Neptune discovery
1846 by Jean-Joseph Le Verrier - after its discovery the position of Uranus didn't match positions predicted by Newton's laws
Uranus's Average Distance from the Sun
19.2 AU
Winds on Neptune
2,000 km/hr winds (strongest in the solar system!!)
Neptune's magnetic field
24x stronger than Earths and stays pretty typical
Uranus's Number of Moons
27
Saturn's Axial Tilt
27 degrees
Neptune's Axial Tilt
28.3 degrees (Similar to Earth, meaning there's well defined seasons)
Saturn's Period of Orbit
29.5 Years
Jupiter's Axial Tilt
3.13 degrees
Distance of the Asteroid Belt from the Sun
3.2-4.2 AU
Neptune's Average Distance from the Sun
30 AU
At each pole, Uranus has.....
42 years of darkness and 42 years of sunlight due to the axial tilt at the poles (Period of orbit = 84 years)
Jupiter's Average Distance from the Sun
5.2 AU
Mass of Saturn
5.683 × 10^26 kg (95 Earths)
Diameter of Uranus
51,200 km
Chemical Composition of the Gas Giants (Jupiter & Saturn)
75% hydrogen, 25% helium
Mass of Uranus
8.681 × 10^25 kg (15 Earth's)
Uranus's Period of Orbit
84.1 Years
Saturn's Average Distance from the Sun
9.5 AU
Jupiter's Rotation Period
9.8 Hours
Chemical Composition of the Sun
92.1% hydrogen, 7.9% helium
Jupiter's Number of Moons
95
Uranus's Axial Tilt
97.8 degrees (Extreme seasons) - this unique tilt makes the planet look like its spinning sideways
How Clouds form on Jupiter
A process called convection - Hot material deeper in Jupiter's interior rises while cooler material sinks. As the hot gases rise, they cool and condense into liquid droplets or ice crystals to form clouds.
Belts of Jupiter
Dark, reddish bands in Jupiter's cloud cover.
Winds on Saturn
Equatorial ones reach almost half a km/sec
Types of Giant planets
Gas & Ice
Atmospheres of Ice Giants
Hydrogen and Helium with some methane
Composition of Jupiter's Interior
Ice, Rock, Metal
Gas Giants
Jupiter and Saturn
Uranus rings
Kept in place by shepherd moons (has 13 of them)
Ices examples
Nitrogen, Carbon, Oxygen, Hydrogen
Storms on Jupiter
No friction to slow storms so some last decades or centuries
Dwarf planet examples
Pluto, Eris, Ceres, Makemake, Haumea
Christian Huygens, 1655
Realized Galileo's "moons" of Saturn are actually rings (believed rings were a solid disk)
James Clerk Maxwell (19th Century)
Realized rings would break apart if they were a solid disk
Why are moons studied?
The similarities and differences between moons is an important part of understanding the way the Solar System formed and continues to evolve
Ice Giants
Uranus and Neptune
"Shepherd" moons definition
a small natural satellite that clears a gap in planetary-ring material or keeps particles within a ring contained
As a result of the pressures and temperatures on Saturn...
ammonia can condense and freeze
Cassini Division
an apparent gap between Saturn's A and B rings (about 4,700 km in width)
Neptune color
dark blue
Jean-Dominique Cassini, 1675
discovered a gap in the "solid" ring system
Neptune's rings
faint and dark, made of clumps of dust (has 6 of them)
Winds on Uranus
far less extreme than Neptune
Uranus's atmosphere is largely _________
featureless
Liquid metallic hydrogen
form of hydrogen with both liquid and metallic properties that exists as a layer in the Jovian atmosphere.
The compositions of Uranus and Neptune are significantly more ________ elements than Jupiter and Saturn
heavy (any material beyond H and He)
Saturn's ring's composition
ice that forms a flat disk & small amounts of silicates
Winds on Jupiter
in opposite direction based on bands (550km/hr at the equator)
Neptune is further from the sun than Uranus but it is warmer by 5 degrees due to....
internal heating
Saturn's ring formation
pieces of comets, asteroids, or shattered moons that broke up before they reached the planet, torn apart by Saturn's powerful gravity
Dwarf planet
planetary object not a planet or moon and is in direct orbit around the sun
The Asteroid Belt
the region of the solar system between the orbits of Mars and Jupiter, where many asteroids are found
Uranus's magnetic field
varies haphazardly (atypical)