Touring our
Solar System
Classes
Home
Overview | Evolution
of the planets | Planets: a brief tour
| Minor members of the solar system | Links
| top | Classes
Home
Overview
- Solar system includes
- Sun
- Nine planets and their satellites
- Asteroids
- Comets
- Meteoroids
- A planet's orbit lies in an orbital plane
- Similar to a flat sheet of paper
- The orbital planes of the planets are inclined
- Planes of seven planets lie within 3 degrees of
the Sun's equator
- Mercury's is inclined 7 degrees
- Pluto's is inclined 17 degrees
- Two groups of planets occur in the solar system
- Terrestrial (Earth-like) planets
- Mercury through Mars
- Small, dense, rocky
- Low escape velocities
- Jovian (Jupiter-like) planets
- Jupiter through Neptune
- Large, low density, gaseous
- Massive
- Thick atmospheres composed of hydrogen, helium,
methane, and ammonia
- High escape velocities
- Pluto not included in either group
- The planets drawn to scale
- Planets are composed of :
- Gases
- Rocks
- Silicate minerals
- Metallic iron
- Ices
- Ammonia (NH3)
- Methane (CH4)
- Carbon dioxide (CO2)
- Water (H2O)
Overview | Evolution
of the planets | Planets: a brief tour
| Minor members of the solar system
| Links | top | Classes
Home |
Evolution of the planets
- Nebular hypothesis
- Planets formed about 5 billion years ago
- Solar system condensed from a gaseous nebula
- Nebular hypothesis - aka Big Bang Theory
- As the planets formed, the materials that compose them
separated
- Dense metallic elements (iron and nickel) sank toward
their centers
- Lighter elements (silicate minerals, oxygen, hydrogen)
migrated toward their surfaces
- Process called chemical differentiation
- Due to their surface gravities, Venus and Earth retained
atmospheric gases
- Due to frigid temperatures, the Jovian planets contain
a high percentage of ices
Overview | Evolution
of the planets | Planets: a brief tour
| Minor members of the solar system
| Links | top | Classes
Home
|
Planets: a brief tour
- Earth's Moon
- General characteristics
- Diameter of 3475 kilometers (2150 miles) is unusually
large compared to its parent planet
- Density
- 3.3 times that of water
- Comparable to Earth's crustal rocks
- Perhaps the Moon has a small iron core
- Gravitational attraction is one-sixth of Earth's
- No atmosphere
- Tectonics no longer active
- Surface is bombarded by micrometeorites from space
which gradually makes the landscape smooth
- Lunar history
- Hypothesis suggests that a giant asteroid collided
with Earth to produce the Moon
- Older areas have a higher density
- Younger areas are still smooth
- Moon evolved in three phases
- (1) Original crust (highlands)
- As Moon formed, its outer shell melted,
cooled, solidified, and became the highlands
- About 4.5 billion years old
- (2) Formation of maria basins
- Younger than highlands
- Between 3.2 and 3.8 billion years old
- (3) Formation of rayed craters
- Material ejected from craters is still
visible
- e.g., Copernicus (a rayed crater)
- Major topographic features on the lunar
surface
- Lunar surface
- Two types of terrain
- Maria (singular, mare), Latin for "sea"
- Dark regions
- Fairly smooth lowlands
- Originated from asteroid impacts and lava
flooding the surface
- Formation of lunar maria
- Highlands
- Bright, densely cratered regions
- Make up most of the Moon
- Make up all of the "back" side
of the Moon
- Older than maria Earth's Moon
- Craters
- Most obvious features of the lunar surface
- Most are produced by an impact from a meteoroid
which produces
- Ejecta
- Occasional rays (associated with younger craters)
- A 20-kilometer-wide crater on the Moon
- Lunar regolith
- Covers all lunar terrains
- "Soil-like" layer produced by meteoric
bombardment
- Composed of
- Igneous rocks
- Breccia
- Glass beads
- Fine lunar dust
- Planets: a brief tour
- Mercury
- Innermost planet
- Second smallest planet
- No atmosphere
- Cratered highlands
- Vast, smooth terrains
- Very dense
- Revolves quickly
- Rotates slowly
- Photomosaic of Mercury
- Venus
- Second to the Moon in brilliance
- Similar to Earth in
- Size
- Density
- Location in the solar system
- Shrouded in thick clouds
- Impenetrable by visible light
- Atmosphere is 97% carbon dioxide
- Surface atmospheric pressure is 90 times that
of Earth's
- Surface
- 80% of surface is subdued plains that are mantled
by volcanic flows
- Low density of impact craters
- Tectonic deformation must have been active during
the recent geologic past
- Thousands of volcanic structures
- Computer generated view of Venus
- Mars
- Atmosphere
- 1% as dense as Earth's
- Primarily carbon dioxide
- Cold polar temperatures (-193ºF)
- Polar caps of water ice, covered by a thin layer of
frozen carbon dioxide
- Extensive dust storms with winds up to 270 kilometers
(170 miles) per hour
- A picture of the Martian landscape from the Viking
1 lander
- Surface
- Numerous large volcanoes largest is Mons
Olympus
- Less-abundant impact craters
- Tectonically dead
- Several canyons
- Some larger than Earths Grand Canyon
- Valles Marineras the largest canyon
- Mons Olympus, an inactive shield volcano on Mars
- The Valles Marineris canyon system on Mars
- "Stream drainage" patterns
- Found in some valleys
- No bodies of surface water on the planet
- Possible origins
- Past rainfall
- Surface material collapses as the subsurface
ice melts
- Moons
- Two moons
- Phobos
- Deimos
- Captured asteroids
- Current Findings:
- Blueberries hematite concretions
- Layered Rocks
- Cross bedding and ripple marks
- Hematite
- Jupiter
- Largest planet
- Very massive
- 2.5 more massive than combined mass of the planets,
satellites, and asteroids
- If it had been ten times larger, it would have
been a small star
- Rapid rotation
- Slightly less than 10 hours
- Slightly bulged equatorial region
- Artists view of Jupiter with the Great Red Spot
visible
- Banded appearance
- Multicolored
- Bands are aligned parallel to Jupiter's equator
- Generated by wind systems
- Great Red Spot
- In planet's southern hemisphere
- Counterclockwise rotating cyclonic storm
- Structure
- Surface thought to be a gigantic ocean of liquid
hydrogen
- Halfway into the interior, pressure causes liquid
hydrogen to turn into liquid metallic hydrogen
- Rocky and metallic material probably exists in
a central core
- Moons
- At least 28 moons
- Four largest moons
- Discovered by Galileo (Galilean satellites)
- Callisto - outermost Galilean moon
- Europa - smallest Galilean moon
- Ganymede - largest Jovian satellite
- Io - innermost Galilean moon and is also volcanically
active
- Close-ups of Io (false color)
- A volcanic eruption on IoJune 28, 1997
(Galileo spacecraft)
- This mosaic of images collected by
NASA's Galileo spacecraft on November
25,1999 shows a fountain of lava spewing
above the surface of Jupiter's moon
Io.Planets: a brief tour
- Saturn
- Similar to Jupiter in its
- Atmosphere
- Composition
- Internal structure
- Rings
- Most prominent feature
- Discovered by Galileo in 1610
- Composed of small particles (moonlets) that orbit
the planet
- Most rings fall into one of two categories based
on particle density
- Thought to be debris ejected from moons
- The ring system of Saturn
- Planets: a brief tour
- Saturn
- Other features
- Dynamic atmosphere
- Large cyclonic storms similar to Jupiter's Great
Red Spot
- Thirty named moons
- Titan the largest Saturnian moon
- Second largest moon (after Jupiter's Ganymede)
in the solar system
- Has a substantial atmosphere
- Uranus
- Uranus and Neptune are nearly twins
- Rotates "on its side"
- Rings
- Large moons have varied terrains
- Neptune
- Dynamic atmosphere
- One of the windiest places in the solar system
- Great Dark Spot
- White cirrus-like clouds above the main cloud
deck
- Eight satellites
- Triton largest Neptune moon
- Orbit is opposite the direction that all the
planet's travel
- Lowest surface temperature in the solar system
(-391ºF)
- Atmosphere of mostly nitrogen with a little methane
- Volcanic-like activity
- Composed largely of water ice, covered with layers
of solid nitrogen and methane
- Pluto
- Not visible with the unaided eye
- Discovered in 1930
- Highly elongated orbit causes it to occasionally travel
inside the orbit of Neptune, where it resided from 1979
thru February 1999
- Moon (Charon) discovered in 1978
- Average temperature is -210ºC
Overview | Evolution
of the planets | Planets: a brief tour
| Minor members of the solar system
| Links | top | Classes
Home |
Minor members of the solar system
- Asteroids
- Most lie between Mars and Jupiter
- Small bodies largest (Ceres) is about 620 miles
in diameter
- Some have very eccentric orbits
- Many of the recent impacts on the Moon and Earth were
collisions with asteroids
- Irregular shapes
- Origin is uncertain The orbits of most asteroids lie
between Mars and Jupiter
- Image of asteroid 951 (Gaspra)
- Comets
- Often compared to large, "dirty snowballs"
- Composition
- Frozen gases
- Rocky and metallic materials
- Frozen gases vaporize when near the Sun
- Produces a glowing head called the coma
- Some may develop a tail that points away from
Sun due to
- Radiation pressure and the
- Solar wind
- Orientation of a comets tail as it orbits
the Sun
- Origin
- Not well known
- Form at great distance from the Sun
- Most famous short-period comet is Halley's comet
- 76 year orbital period
- Potato-shaped nucleus (16 km by 8 km)
- Comet Hale-Bopp
- Meteoroids
- Called meteors when they enter Earth's atmosphere
- A meteor shower occurs when Earth encounters a swarm
of meteoroids associated with a comet's path
- Meteoroids are referred to as meteorites when they
are found on Earth
- Types of meteorites classified by their composition
- Irons
- Stony
- Silicate minerals with
- Inclusions of other minerals
- Stony-irons mixtures
- Carbonaceous chondrites
- Rare
- Composition - simple amino acids and other organic
material
- May give an idea as to the composition of Earth's
core
- Give an idea as to the age of the solar system
Overview | Evolution
of the planets | Planets: a brief tour
| Minor members of the solar system
| Links | top | Classes
Home |
|