solar system
TRANSCRIPT
Solar Nebula Hypothesis
• Explains that the planets formed through condensing of the solar nebula.
• Solar Nebula: a rotating cloud of gas and dust from which the sun and planets formed; also any nebula from which stars and planets may form.
• Nebula: a cloud of gas and dust in space.
Units for Measuring Distance in Space1. Light Year: the distance light can travel in
one year.• Used for distances outside our Solar System.• Light moves at about 300,000 km/second• So, in one year it can travel 10 trillion km.2. Astronomical Unit (AU): the average
distance between the Earth and the Sun.• The distance between the Earth and Sun is
equal to 1 AU.• used for distances within our Solar System.• 1 AU = 150 million km (93 million miles).
The Eight Planets
Inner/Terrestrial Planets:• Mercury• Venus• Earth• Mars
Between the Inner & Outer• Asteroid Belt
Outer/Jovian Planets:• Jupiter• Saturn• Uranus• Neptune
Dwarf Planet:• Pluto
Inner/Terrestrial Planets
• Terrestrial: means ‘earth’ like planet.
• are relatively small,
• composed mostly of rock
• have few or no moons.
Outer/Jovian Planets
• Jovian: ‘Jupiter’ like planets
• are mostly huge
• mostly gaseous, ringed
• have many moons
Temperatures on Planets
• Generally, the farther from the Sun, the cooler the planet.
• Differences occur when the greenhouse effect warms a planet (like Venus) surrounded by a thick atmosphere of CO2.
Density of the Planets
• The outer, gaseous planets are much less dense than the inner, rocky planets.
• The Earth is the densest planet.
• Saturn is the least dense planet; it would float on water.
Mass of the Planets
• Jupiter is by far the most massive planet; Saturn trails it.
• Uranus, Neptune, Earth, Venus, Mars, and Pluto are orders of magnitude less massive.
Gravity on the Planets
• Strongest gravitational attraction at its surface is Jupiter.
• Although Saturn, Uranus, and Neptune are also very massive planets, their gravitational forces are about the same as Earth.
• Click on picture to determine your weight on other planets.
A Day on Each of the Planets• A day is the length of time that
it takes a planet to rotate on its axis (360°).
• A day on Earth takes almost 24 hours.
• The planet with the longest day is Venus; a day on Venus takes 243 Earth days. (A day on Venus is longer than its year; a year on Venus takes only 224.7 Earth days).
• The planet with the shortest day is Jupiter; a day on Jupiter only takes 9.8 Earth hours!
Average Orbital Speed of Planets
• Planets travel at different speeds.
• Each planet speeds up when it is nearer the Sun and travels more slowly when it is far from the Sun (Kepler's Second Law of Planetary Motion).
• Click on picture to right and determine your age on another planet.
Mercury• Closest planet to the Sun (therefore, you can only
see it close to sunrise or sunset)• Has a very thin atmosphere• Heavily cratered (atmosphere too thin to break apart
incoming meteorites)• Has no moons• Huge range in temperatures, from -270°F to 800°F
(-168°C to 427°C). • During the very long daytime (88 Earth-days long),
the temperatures are very high (the second-highest in the Solar System - only Venus is hotter);
• During the long night, the thin atmosphere lets the heat dissipate, and the temperature drops quickly.
Venus• A.K.A. the ‘morning star’ or the ‘evening star’• Hottest planet in our Solar System (due to an
atmosphere composed of CO2 which traps heat)
• Has no moons• Venera 3 (from the U.S.S.R.) was the first
manmade object to reach Venus (launched on November 16, 1965).
• On March 1, 1966 , the spacecraft arrived at Venus and the capsule parachuted down to the planet, but contact was lost just before entry into the atmosphere.
• Earth’s sister planet.
Earth• ‘3rd rock from the sun’.• Has an atmosphere (composed of 78% nitrogen,
21% oxygen, 0.9% argon, 0.03% carbon dioxide, and trace amounts of other gases).
• The atmosphere was formed by planetary degassing (a process in which gases like carbon dioxide, water vapor, sulphur dioxide and nitrogen were released from the interior of the Earth from volcanoes and other processes).
• Life forms on Earth have modified the composition of the atmosphere since their evolution.
• Has one moon.• Has water in all three states (solid, liquid, gas)
Mars• 4th planet from the sun.• The Red planet• About half the size of Earth• Has a dry, rocky surface and a very thin atmosphere. • North and south poles of Mars are covered by ice
caps composed of frozen carbon dioxide and water.• Scientists have long thought that there is no liquid
water on the surface of Mars now, but recent photos from Mars indicate that there might be some liquid water near the surface.
• Scientists think that most of the water on Mars is frozen in the land (as permafrost) and frozen in the polar ice caps.
Mars• Olympus Mons, the
largest volcano on Mars; • It is perhaps the largest
volcano in the Solar System.
• It is 17 miles (27 km) tall and over 320 miles (520 km) across.
• It is thought to be extinct.
Asteroid Belt• The area between the inner and outer planets• The current view is that asteroids are leftover rocky matter that
never successfully formed into a planet.• Click on the left picture and see asteroids that come close to
Earth.
Jupiter• Largest planet in our solar system.
• Has a thick atmosphere, 39 known moons, and a dark, barely-visible ring.
• Its most prominent features are bands across its latitudes and a great red spot (which is a storm).
• Composed mostly of gas.
• Radiates twice as much heat as it absorbs from the Sun.
Jupiter’s Moons
• Jupiter has at least 39 moons.
The Four Galilean Moons (discovered by Galileo)
1. Io (volcanically active)
2. Europa
3. Ganymede (largest moon in solar system)
4. Callisto
1. Io
• is a large, rocky, volcanically active moon of Jupiter.
• Is the innermost of Jupiter's four large moons and the third largest.
2. Europa
• Is a large, dense, icy moon of Jupiter.
• Europa is the smoothest object in our Solar System.
• Its surface is covered with long, crisscrossing trackways (but few craters) on water ice.
3. Ganymede
• Is the largest moon of Jupiter
• A large, icy, outer moon that is scarred with impact craters and many parallel faults.
4. Callisto
• Is a large, icy, dark-colored, low-density outer moon of Jupiter that
• It is scarred with impact craters and ejecta.
Saturn• It is the second-largest planet in our solar
system (Jupiter is the largest). • It has beautiful rings made mostly of ice chunks
(and some rock) that range in size from the size of a fingernail to the size of a car.
• Saturn is made mostly of hydrogen and helium gas.
• Saturn is the only planet in our Solar System that is less dense than water. Saturn would float if there were a body of water large enough!
Saturn’s Moons
• Saturn has dozens of moons (33 discovered as of August, 2004).
• It has 18 named moons, including: – Titan (the largest), Rhea, Iapetus, Dione, Tethys,
Enceladus, Mimas, Hyperion, Phoebe, Janus, Epimetheus, Pandora, Prometheus, Helene, Telesto, Atlas, Calypso, and Pan (the smallest named moon of Saturn). At least a dozen others have been noted (but not named yet).
Saturn’s Rings
Uranus
• This huge, icy planet is covered with clouds and is encircled by a belt of 11 rings and 22 known moons.
• Uranus' blue color is caused by the methane (CH4) in its atmosphere; this molecule absorbs red light.
• Uranus rotates on its side (along its orbital path). • This tipped rotational axis (97.90) gives rise to
extreme seasons • A catastrophic collision with another large body
eons ago may have tipped Uranus over on its side.
Uranus
Neptune• This giant, frigid planet has a hazy atmosphere and
strong winds. • This gas giant is orbited by 8 moons and narrow,
faint rings arranged in clumps.• Neptune's blue color is caused by the methane
(CH4) in its atmosphere; this molecule absorbs red light.
• Neptune's rotational axis is tilted 30 degrees (this is a few degrees more than the Earth).
• This gives Neptune seasons. • Each season lasts 40 years; the poles are in
constant darkness or sunlight for 40 years at a time.
Neptune
A Planet vs. Pluto the Dwarf
International Astronomical Union’s Definition of a
Planet:• Is in orbit around the
sun.• Is nearly round.• Has cleared the
neighborhood around its orbit.
International Astronomical Union’s Definition of a
Dwarf Planet:• Is in orbit around the
sun.• Is nearly round• Has not cleared the
neighborhood around its orbit.
• Is not a satellite.
Pluto the Dwarf Planet• Pluto’s Failure to Remain a Planet: It has not
cleared the neighborhood around its orbit.
• Each day on Pluto takes 6.39 Earth days.
• Each year on Pluto takes 247.7 Earth years (that is, it takes 247.7 Earth years for Pluto to orbit the Sun once).
• Sometimes it is even closer to the Sun than the planet Neptune (it was that way from January 1979 to February 11, 1999)!
Pluto
• Pluto has one large moon, named Charon;
• Two minscule moons were discovered in 2005.
• Pluto's composition is unknown.
• It is probably made up of about 70% rock and 30% water. This is determined from density calculations
References
• http://www.enchantedlearning.com/subjects/astronomy/planets/
• http://www.solarviews.com/eng/jupiter.htm