The Solar System Tour of the Solar System
The Sun more later 8 planets Mercury Venus Earth more later Mars Jupiter Saturn Uranus Neptune Various other objects Asteroids Comets Pluto
The Terrestrial Planets Mercury Venus Earth Mars Characteristics Small Rocky Very close to Sun Have few moons Have no rings
Mercury
Photographs from Mariner 10 reveal Mercury s lunar-like surface Mercury Moon
Cratering of Mercury Mercury has a mixture of heavily cratered and smooth regions like the Moon. The smooth regions are likely ancient lava flows.
The surface of Venus is completely hidden beneath permanent cloud cover The surface temperature of Venus is approximately 470 C
Surface Features Impact craters, but fewer than Moon, Mercury, Mars Many volcanoes
Tectonics on Venus Fractured and contorted surface indicates tectonic stresses
Erosion on Venus Photos of rocks taken by lander show little erosion
Atmosphere of Venus Venus has a very thick carbon dioxide atmosphere with a surface pressure 90 times that of Earth.
Greenhouse Effect on Venus Thick carbon dioxide atmosphere produces an extremely strong greenhouse effect. Earth escapes this fate because most of its carbon and water are in rocks and oceans.
Atmosphere of Venus Reflective clouds contain droplets of sulfuric acid. The upper atmosphere has fast winds that remain unexplained.
EARTH More later
Mars As seen from the Hubble Space Telescope
Past tectonic activity Volcanoes as recent as 180 million years ago Low-lying regions may once have had oceans.
2004 Opportunity Rover provided strong evidence for abundant liquid water on Mars in the distant past.
Today, most water lies frozen underground (blue regions) Some scientists believe accumulated snowpack melts to carve gullies even today
Martian Polar Caps and Climate The atmosphere of Mars has an average surface pressure of only 0.007 bar, less than 1% of that of the Earth. The Martian atmosphere is composed primarily of carbon dioxide (95%). May 19, 2005 Mars Exploration Rover Spirit At Gusev Crater, Mars Image Credit: NASA/JPL/Texas A& M/Cornell
Dust clouds, raised by winds, can form. Sometimes these grow to produce global dust storms. Clouds on Mars
Water-ice clouds similar to those on Earth also form around mountains, especially near the Tharsis volcanoes in the mornings and afternoons.
Most asteroids orbit the Sun between Mars and Jupiter
In general, asteroids are small
The Jovian (Giant) Planets Jupiter Saturn Uranus Neptune Characteristics Large Gaseous Far from Sun Many moons Rings
Jovian Planet Statistics All the Jovian planets have strong winds and storms
Jupiter is the Largest of the Gas Giant Planets Jupiter s Great Red Spot A hurricane like storm that has been observed ever since discovered by Galileo (close to 400 years)
Jupiter has four large moons and many smaller ones
Io is the most volcanically active body in the solar system
Europa may harbor liquid water below its icy surface
Ganymede Largest moon in the solar system Clear evidence of geological activity Tidal heating plus heat from radioactive decay?
Callisto Classic cratered iceball No tidal heating, no orbital resonances But it has magnetic field!?
Saturn has the most extensive ring system in the solar system Saturn s ring system is composed of fragments of ice and ice coated rock
Titan Titan is Saturn s largest moon Titan is the only moon in the solar system that has a thick atmosphere. It consists mostly of nitrogen with some argon, methane, and ethane.
Mimas Smallest and innermost of Saturn s major moons Composed mainly of rock and ice Giant Herschel crater on one side
Ongoing Activity on Enceladus Fountains of ice particles and water vapor from the surface of Enceladus indicate that geological activity is ongoing.
Saturn and Jupiter share the same basic structure
A system of rings and satellites revolves around Uranus Uranus has a hazy atmosphere with few clouds
Uranus odd moon Miranda
Brilliant blue Neptune has a giant storm too
Neptune s Rings
Neptune s largest moon, Triton, was probably captured by Neptune s gravity
Uranus and Neptune have similar interiors
Kuiper Belt Objects These large, icy objects have orbits similar to the smaller objects in the Kuiper belt that become short period comets. So are they very large comets or very small planets?
Pluto and Other Icy Bodies There are many icy objects like Pluto on elliptical, inclined orbits beyond Neptune. The largest ones are comparable in size to Earth s Moon.
Nucleus of Comet A dirty snowball Source of material for comet s tail
Anatomy of a Comet Coma is atmosphere that comes from heated nucleus. Plasma tail is gas escaping from coma, pushed by solar wind. Dust tail is pushed by photons.
Growth of Tail
Comets eject small particles that follow the comet around in its orbit and cause meteor showers when Earth crosses the comet s orbit.
Meteors in a shower appear to emanate from the same area of sky because of Earth s motion through space.
Only a tiny number of comets enter the inner solar system; most stay far from the Sun. Oort cloud: On random orbits extending to about 50,000 AU Kuiper belt: On orderly orbits from 30 to 100 AU in disk of solar system