Intro To The Solar System 2010

Introduction to theSolar System

The bright star Antares embedded in dust and gases

Origin of the Solar SystemOrigin of the Solar System

Modern astronomers believe that the sun and Modern astronomers believe that the sun and planets condensed out of a nebula or large planets condensed out of a nebula or large cloud of gas and dust. cloud of gas and dust.

This idea is named the Nebular Hypothesis. It This idea is named the Nebular Hypothesis. It was first presented by the German philosopher was first presented by the German philosopher Immanuel Kant in the late 1700’s. Immanuel Kant in the late 1700’s.

Such clouds have been observed around stars Such clouds have been observed around stars other than our sun (e.g., Beta Pictoris)other than our sun (e.g., Beta Pictoris)

The Formation of the Solar SystemThe Formation of the Solar System

Our solar system began as a rotating gas cloud or nebula that collapsed toward its center under the influence of gravity.

A condensation formed at the center, which is called a protostar.

A flattened disk of matter surrounded the protostar, which begtan to shine and become a star, our sun.

The Formation of our Solar SystemThe Formation of our Solar System

The rising temperature from the sun removed the gas from the inner regions, leaving dust and larger debris

•Inner planets formed from solid debris

•Outer planets retained original gases

Planets established dominance in their regions of the solar system.

After almost all of the remaining gas, dust, and small debris was collected by the larger objects, the solar system took on the form we recognize today.

Other Star Systems FormingOther Star Systems Forming

•We can look at young star systems developing today.

•The planets orbiting these stars are formed from the surrounding disks of gas and dust, called protoplanetary disks or proplyds.

Proplyd in the Orion Nebula

Beta PictorisBeta Pictoris

May represent May represent new solar new solar system in system in formationformation

Disk of gas, Disk of gas, dust seen dust seen edge-on, star edge-on, star Beta in center Beta in center (covered to (covered to reveal faint reveal faint outer disk)outer disk)

Solar System CompositeSolar System Composite

http://www2.jpl.nasa.gov/galileo/sepo/education/nav/ss2.gif

1. Mercury

2. Venus

3. Earth

4. Mars

5. Jupiter

6. Saturn

7. Uranus

8. Neptune

Common Properties of Common Properties of Planet Orbits in Our Planet Orbits in Our Solar SystemSolar System

As viewed from above, all of the planets orbit the Sun in a counterclockwise direction.

The planets orbit in nearly the same plane (ecliptic). All planets except Pluto have an orbital inclination of less than 7°.

Inner Solar SystemInner Solar System

http://www.nineplanets.org/overview.html

Outer Solar SystemOuter Solar System

http://www.nineplanets.org/overview.html

Pluto’s Odd OrbitPluto’s Odd Orbit

Pluto’s orbit, or Pluto’s orbit, or plane of revolution, plane of revolution, is tilted by 17is tilted by 17° to ° to the general solar the general solar system orbits system orbits (ecliptic)(ecliptic)

Pluto can also cut Pluto can also cut across Neptune’s across Neptune’s orbit (but they can orbit (but they can never collide)never collide)

Ecliptic PlaneEcliptic Plane

Plane of the EclipticPlane of the Ecliptic: The orbits of the planets : The orbits of the planets are mostly in the same plane. are mostly in the same plane.

This plane is called the ecliptic and is defined by This plane is called the ecliptic and is defined by the plane of the earth’s orbit. the plane of the earth’s orbit.

The exception is Pluto, which is tilted quite a bit The exception is Pluto, which is tilted quite a bit in comparison to the rest of the planets.in comparison to the rest of the planets.

The ecliptic plane is a remnant of the original, The ecliptic plane is a remnant of the original, rotating nebular disk that formed the sun and rotating nebular disk that formed the sun and planetsplanets

Ecliptic: Artist’s ViewEcliptic: Artist’s View

MotionsMotions

Directions of MotionDirections of Motion: The planets orbit in a : The planets orbit in a counterclockwise direction around the sun counterclockwise direction around the sun (when looking down upon the solar system (when looking down upon the solar system from the sun’s north pole). from the sun’s north pole).

All the planets, except for Venus, Uranus, All the planets, except for Venus, Uranus, and Pluto, rotate in the same direction as and Pluto, rotate in the same direction as their orbits.their orbits.

SS RevolutionSS Revolution

All planets All planets revolve revolve counter-counter-clockwise clockwise when viewed when viewed from abovefrom above

OrbitsOrbits

The planets nearest to the Sun (Mercury, The planets nearest to the Sun (Mercury, Venus, Earth, and Mars) are relatively Venus, Earth, and Mars) are relatively close together, while those farther away close together, while those farther away (Jupiter, Saturn, Uranus, and Neptune) are (Jupiter, Saturn, Uranus, and Neptune) are more spread out.more spread out.

Most of the planets are in nearly circular Most of the planets are in nearly circular orbits. orbits.

Solar System Orbits (AU)Solar System Orbits (AU) The astronomical unit The astronomical unit

(AU) is useful in (AU) is useful in measuring distances in measuring distances in the solar systemthe solar system

One AU equals the One AU equals the average earth-to-sun average earth-to-sun distance of 93 million distance of 93 million milesmiles

AU distances allow direct AU distances allow direct comparison to the earth comparison to the earth which is equal to 1.0which is equal to 1.0

PlanetPlanet Distance in AUDistance in AU

MercuryMercury 0.40.4

VenusVenus 0.70.7

EarthEarth 1.01.0

MarsMars 1.51.5

JupiterJupiter 5.25.2

SaturnSaturn 9.59.5

UranusUranus 19.219.2

NeptuneNeptune 3030

PlutoPluto 39.539.5

Revolutions of the Planets*Revolutions of the Planets*

Mercury 88 daysMercury 88 days Venus 224.7 daysVenus 224.7 days Earth 365.25 daysEarth 365.25 days

Mars 1.88 yearsMars 1.88 years Jupiter 11.86 yearsJupiter 11.86 years Saturn 29.5 yearsSaturn 29.5 years Uranus 84 yearsUranus 84 years Neptune 164.79 yearsNeptune 164.79 years Pluto 248.32 yearsPluto 248.32 years

*Earth days and years*Earth days and years

DiametersDiameters

PlanetPlanet Diameter (Earth = 1)Diameter (Earth = 1)


VenusVenus 0.950.95

EarthEarth 1.01.0

MarsMars 0.530.53


SaturnSaturn 9.459.45


NeptuneNeptune 3.883.88

PlutoPluto 0.180.18

MassesMasses

PlanetPlanet Mass (Earth = 1)Mass (Earth = 1)


VenusVenus 0.810.81

EarthEarth 1.01.0

MarsMars 0.110.11


SaturnSaturn 95.1895.18


NeptuneNeptune 17.1417.14

PlutoPluto 0.0020.002

Average Density (kg/mAverage Density (kg/m33))

PlanetPlanet Average Density (kg/mAverage Density (kg/m33))

MercuryMercury 54305430

VenusVenus 52505250

EarthEarth 55205520

MarsMars 39503950

JupiterJupiter 13301330

SaturnSaturn 690690

UranusUranus 12901290

NeptuneNeptune 16401640

PlutoPluto 20302030

Rotational PeriodRotational PeriodPlanet Days (Earth 1)

Mercury 58.6462

Venus 243.0187

Earth 0.99727

Mars 1.025957

Jupiter 0.41354

Saturn 0.42637

Uranus 0.71806

Neptune 0.67125

Pluto 6.3872

Average TemperatureAverage TemperaturePlanet Ave Temp (°F)

Mercury 354°

Venus 867°

Earth 45°

Mars -81°

Jupiter -186°

Saturn -202°

Uranus -337°

Neptune -364°

Pluto -380°

Average Temperature (Earth = 1)

Sizes of the PlanetsSizes of the Planets In mass, In mass, the sun represent 99% of the sun represent 99% of

the solar systemthe solar system The smallest planet, Mercury, has a The smallest planet, Mercury, has a

diameter of 3031 midiameter of 3031 mi Pluto, the previous smallest planet, Pluto, the previous smallest planet,

has a diameter of 1457 mihas a diameter of 1457 mi The largest planet, Jupiter, has a The largest planet, Jupiter, has a

diameter of 88,700 midiameter of 88,700 mi Earth = 7926 miEarth = 7926 mi Ganymede, the largest moon of Ganymede, the largest moon of

Jupiter, is larger than Mercury, yet Jupiter, is larger than Mercury, yet Ganymede is not considered a Ganymede is not considered a planet because it revolves around planet because it revolves around JupiterJupiter

http://www.nineplanets.org/datamax.html

Two Basic Groups of PlanetsTwo Basic Groups of Planets

TERRESTRIAL (earth-like)TERRESTRIAL (earth-like)

Small size, low MassSmall size, low Mass

Higher densityHigher density

Mostly rockMostly rock

Mercury, Venus, Earth, MarsMercury, Venus, Earth, Mars

JOVIAN (Jupiter-like)JOVIAN (Jupiter-like)

Large size, massiveLarge size, massive

Low densityLow density

Mostly gasMostly gas

Jupiter, Saturn, Uranus, Jupiter, Saturn, Uranus, NeptuneNeptune

ClassificationsClassifications

Terrestrial or Rocky planetsTerrestrial or Rocky planets——Composed of rock and metal: Mercury, Composed of rock and metal: Mercury, Venus, Earth, MarsVenus, Earth, Mars

Jovian or Gas planetsJovian or Gas planets—Composed —Composed primarily of the gases hydrogen and primarily of the gases hydrogen and helium: Jupiter, Saturn, Uranus, Neptunehelium: Jupiter, Saturn, Uranus, Neptune

Classification, cont.Classification, cont.

Small PlanetsSmall Planets—Diameters less than —Diameters less than 13,000 km: Mercury, Venus, Earth, Mars13,000 km: Mercury, Venus, Earth, Mars

Giant Planets (Gas Giants)Giant Planets (Gas Giants)—Diameters —Diameters greater than 48,000 km: Jupiter, Saturn, greater than 48,000 km: Jupiter, Saturn, Uranus, NeptuneUranus, Neptune


Inner PlanetsInner Planets—Mercury, Venus, Earth, —Mercury, Venus, Earth, MarsMars

Outer PlanetsOuter Planets—Jupiter, Saturn, Uranus, —Jupiter, Saturn, Uranus, NeptuneNeptune


InferiorInferior—Closer to the sun than earth: —Closer to the sun than earth: Mercury and VenusMercury and Venus

SuperiorSuperior—Farther from the sun than —Farther from the sun than earth: Mars, Jupiter, Saturn, Uranus, earth: Mars, Jupiter, Saturn, Uranus, NeptuneNeptune


ClassicalClassical—Known since prehistoric times, —Known since prehistoric times, visible to the unaided eye: Mercury, visible to the unaided eye: Mercury, Venus, Mars, Jupiter, SaturnVenus, Mars, Jupiter, Saturn

ModernModern—Discovered in modern times, —Discovered in modern times, visible only with telescopes: Uranus, visible only with telescopes: Uranus, Neptune, (Pluto)Neptune, (Pluto)

Classification TableClassification Table

PlanetPlanet Rocky or Rocky or Gas?Gas?

Small or Small or Giant?Giant?

Inner or Inner or Outer?Outer?

Inferior or Inferior or Superior?Superior?

Classical Classical or or Modern?Modern?

MercuryMercury RR SS II II CC

VenusVenus RR SS II II CC

EarthEarth RR SS II N/AN/A ??

MarsMars RR SS II SS CC

JupiterJupiter GG GG OO SS CC

SaturnSaturn GG GG OO SS CC

UranusUranus GG GG OO SS MM

NeptuneNeptune GG GG OO SS MM

PlutoPluto ?? SS OO SS MM

New Solar System (> 2006)New Solar System (> 2006) PlanetsPlanets::

MercuryMercury VenusVenus EarthEarth MarsMars

Ceres (dwarf)Ceres (dwarf)

JupiterJupiter SaturnSaturn UranusUranus NeptuneNeptune

Pluto (dwarf)Pluto (dwarf) Eris (dwarf)Eris (dwarf) Makemake (dwarf)Makemake (dwarf)

Eris

•Two Categories: Planets and Dwarf Planets (dwarfs beyond Neptune are “Plutoids”)

•Today’s astronomers recognize only 8 planets

Solar System ModelSolar System Model If the sun were an orange, the earth would be a If the sun were an orange, the earth would be a

grain of sand thirty feet away.grain of sand thirty feet away. Jupiter would be a cherry pit located one block Jupiter would be a cherry pit located one block

from the sun. from the sun. Saturn would be another cherry pit located one Saturn would be another cherry pit located one

block from Jupiter. block from Jupiter. Pluto would be a grain of sand 10 blocks from Pluto would be a grain of sand 10 blocks from

the sun. the sun. The nearest star to our sun (Alpha Centauri) The nearest star to our sun (Alpha Centauri)

would be represented as another orange 2000 would be represented as another orange 2000 miles from the sun. miles from the sun.

Planet NamesPlanet Names

The planets have been given the Roman The planets have been given the Roman names of gods from ancient Greece.names of gods from ancient Greece.

RomanRomanMercury, Venus, Mars, Jupiter, SaturnMercury, Venus, Mars, Jupiter, Saturn

GreekGreekHermes, Aphrodite, Ares, ZeusHermes, Aphrodite, Ares, Zeus,, Kronos Kronos

The modern planets, Uranus, Neptune, and The modern planets, Uranus, Neptune, and Pluto, are also Roman godsPluto, are also Roman gods

Jupiter from Fantasia (Disney)

Intro To The Solar System 2010

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