THE SOLAR SYSTEM

OUR SOLAR SYSTEM IS THOUGHT TO BE 4.5 BILLION YEARS OLD.

IT WAS FORMED FROM A NEBULA CONTAINING MATERIAL THAT HAD BEEN THROUGH 2 PREVIOUS SUPER NOVAE.

99.9% OF THE MASS OF THE SOLAR SYSTEM IS FOUND IN THE SUN.

THE MOON WAS FORMED SHORTLY AFTER EARTH WHEN A MARS SIZED PLANET COLLIDED WITH EARTH.

UNITS OF MEASURMENT IN ASTRONOMY

ASTRONOMICAL UNIT, AU = 93,000,000 MILES = 150,000,000 km = AVERAGE DISTANCE FROM EARTH TO THE SUN

LIGHT YEAR = 5.9 X 1012 MILES = 9.5 X 1012 km = THE DISTANCE LIGHT TRAVELS IN ONE YEAR

Speed of light = 186,000 mi/sec = 3 x 108 meters/sec

OUR SOLAR SYSTEM CONSISTS OF:

•AN AVERAGE STAR, OUR SUN

•8 PLANETS (not counting Pluto)

•THE ASTEROID BELT – BETWEEN MARS AND JUPITER

•THE KUIPER BELT – WHERE PLUTO AND A NUMBER OF OTHER PLANETESIMALS ARE LOCATED

•THE OORT CLOUD – FURTHEREST REACHES

THE PLANETS ARE (in order) MERCURY, VENUS, EARTH, MARS, JUPITER, SATURN, URANUS, AND NEPTUNE.

THEY ALL ORBIT THE SUN IN APPROXIMATELY THE SAME PLANE - THE ECLIPTIC.

Planet Distance x 106 km

Distance in AU

Period to Revolve

Around Sun

Mercury 57.91 0.4 88 days

Venus 108.21 0.7 224.7 days

Earth 149.6 1.0 365 days

Mars 227.92 1.5 687 days

Jupiter 778.57 5.0 11.75 yrs

Saturn 1433.53 10 29.5 yrs

Uranus 2872.46 20 84 yrs

Neptune 4495.06 30 165 yrs

The terrestrial planets - mercury, venus, earth, and mars - sometimes referred to as the rocky planets.

MERCURY

Diameter – 3031 miles (38% of Earth’s)

Mass – 5.5% of Earth’s

Distance from sun – from 28 million miles to 43 million miles

Surface gravity – 38% of Earth’s

Average surface temperature – 800o F

Atmosphere – none

Satellites – none

Sunlight – 1000% of Earth’s

MERCURY

Rotates in 58.65 earth days – orbits in 87.98 earth days.

VENUS

Diameter – 7521 miles (94.8% of Earth’s)

Mass – 95% of Earth’s

Surface gravity – 90% of Earth’s

Average surface temperature – 900o F

Distance from sun – approx. 67,000,000 mi.

Sunlight – 190% of Earth’s

Atmosphere – 96% carbon dioxide, 3.2% nitrogen and 0.8% other

Satellites - none

VENUS

Rotates in 243 days – orbits 225 days.

EARTH

Diameter – 7926 miles

Mass – 1.3 x 1025 pounds

Distance from sun – approx. 93,000,000 miles

Average surface temperature – 56o F

Number of satellites – 1

Atmosphere – 78% nitrogen, 21% oxygen, 0.9% argon, 0.1% other

EARTH

Rotates in 23 hours, 56 min – orbits in 365.4 days.

IT IS A LONELY PLACE.

THE NEAREST STAR IS 4.22 LIGHT YEARS AWAY.

THE OTHER PLANETS IN OUR SOLAR SYSTEM ARE NOT CAPABLE OF SUPPORTING LIFE AS WE KNOW IT.

VENUS HAS AN ATMOSPHERE OF MOSTLY CARBON DIOXIDE AND A SURFACE TEMPERATURE OF 472o K.

MARS HAS A VERY THIN ATMOSPHERE OF MOSTLY CARBON DIOXIDE AND A SURFACE TEMPERATURE OF -140o TO 20o C.

MARS

Diameter – 4221 miles ( 53.2% of Earth’s)

Mass – 11% of Earth’s

Distance from sun – from 128 million miles to 155 million miles

Sunlight – 36 – 52% of Earth’s

Surface gravity – 38% of Earth’s

Average surface temperature - -10o F

Satellites – 2

Atmosphere – 95% carbon dioxide, 2.7% nitrogen, 1.6% argon, 0.7% other

MARS

Rotates in 24 hours, 37 min – orbits in 687 days.

MERCURY VENUS EARTH MARS

DIAMETER 3031 mi 7512 mi 7926 mi 4221 mi

MASS 5% of Earth

95% of Earth

1.3 x 1025 pounds

11% of Earth

AV. TEMP. 800o F 900o F 56o F - 20o F

ATMOSPHERE

Very thin 96% CO2

Dense*

79% N2

20% O2

95% CO2

2.7% N2

ROTATION 58 days 243 days 24 hrs 24 hrs

ORBIT 88 days 225 days 365 days 687 days

* Surface pressure on Venus is 90 atmospheres.

ASTEROID BELT

EXTENDS FROM 2.15 au TO 3.3 au.

THE INNER ASTEROIDS ORBIT THE SUN IN APPROX 3 YEARS, WHILE THE OUTER ASTEROIDS TAKE APPROX. 6 YEARS.

THERE IS NO RELIABLE ESTIMATE OF THE NUMBER OF ASTEROIDS.

THE TOTAL MASS IS THOUGHT TO BE AROUND 1/20th OF THE MASS OF OUR MOON.

THE LARGEST ASTEROID IS CERES, WHICH IS 650 MILES ACROSS.

MOST ARE LESS THAN 30 FEET.

JUPITER

DISTANCE FROM SUN = 5.2 AU

MASS = 318 X EARTH

DIAMETER = 11 X EARTH

ATMOSPHERE = HYDROGEN AND HELIUM

SURFACE = LIQUID HYDROGEN

ORBIT = 12 YEARS

ROTATION = 10 HOURS

MOONS = 63 (4 GALILEAN MOONS)

ONE OBVIOUS FEATURE IS THE GREAT RED SPOT, WHICH IS LARGE ENOUGH TO PUT TWO EARTHS IN SIDE-BY-SIDE.

IT IS A LARGE STORM, AND IT HAS LASTED FOR OVER 300 YEARS.

Io, Europa, Ganymede, and Callisto

TIDAL FORCES HEAT THE INTERIOR OF THE TWO INNERMOST MOONS.

IO HAS TREMENDOUS VOLCANIC ERUPTIONS.

IO IS 2% LARGER THAN EARTH’S MOON.

EUROPA HAS A SHELL OF WATER ICE, WHICH IS ESTIMATED TO BE BETWEEN 12 AND 90 mi THICK.

EUROPA IS ABOUT 12% SMALLER THAN EARTH’S MOON.

CASTILLO AND GANYMEDE ARE BOTH SLIGHTLY LARGER THAN THE PLANET MERCURY.

BOTH MAY HAVE LIQUID OCEANS DEEP BENEATH THEIR ICY CRUSTS.

JUPITER MAY HAVE A ROCKY IRON/NICKEL CORE 1.5 TIMES EARTH’S DIAMETER.

DUE TO THE EXTREME GRAVITY, THE CORE TEMPERATURE MAY BE AS HIGH AS 20,000o C.

SATURN

DISTANCE FROM SUN = 9.5 AU

DIAMETER = 9.4 EARTH

MASS = 95 X EARTH

ORBIT = 29.5 YEARS

ROTATION = 11 HOURS

THOUGHT THAT SATURN HAS A CORE APPROX. 2.5 TIMES EARTH’S DIAMETER, 20 TIMES EARTH’S MASS, AND 15% OF JUPITER’S TOTAL MASS.

THE PLANET IS MADE MOSTLY OF MOLECULAR HYGROGEN (88%) AND HELIUM (11%).

SATURN’S RINGS ARE VERY THIN. THEY ARE 250,000 km ACROSS, BUT THEY ARE ONLY 1 km THICK.

THERE IS NOT MUCH MATERIAL THERE. IF IT WERE ALL COMPRESSED INTO A SINGLE OBJECT, IT WOULD ONLY BE 100 km THICK.

LIKE JUPITER, SATURN RADIATES MORE ENERGY THAN IT RECEIVES FROM THE SUN.

ALSO, LIKE JUPITER, SATURN HAS A STRONG MAGNETIC FIELD.

SCIENTISTS THINK THIS IS CAUSED BY THE METALLIC HYDROGEN IN THE INTERIOR.

TITAN IS THE LARGEST MOON OF SATURN.

IT HAS AN ATMOSPHERE COMPOSED MOSTLY OF NITROGEN AND METHANE.

THE ATMOSPHERIC PRESSURE AT THE SURFACE IS 1.6 TIMES THAT OF EARTH.

THE SURFACE OF TITAN IS COVERED WITH HYDROCARBON LAKES, PRIMARILY METHANE AND ETHANE.

PICTURE OF TITAN SHOWING ITS ATMOSPHERE.

SATURN WAS THE FURTHEREST PLANET FROM THE SUN KNOWN TO THE ANCIENTS.

URANUS WAS NOT DISCOVERED UNTIL 1781 BY WILLIAM HERSCHEL USING A TELESCOPE.

URANUS

DIAMETER = 4 X EARTH

MASS = 11 X EARTH

DISTANCE FROM SUN = 19.2 AU

ROTATION = 17 HOURS

ORBIT = 84 YEARS

THE ROTATIONAL AXIS IS ONLY 8 DEGREES OUT OF THE PLANE OF THE ORBIT, SO WE SEE IT ON ITS SIDE.

COMPOSITION = MOSTLY HYDROGEN AND HELIUM.

MOONS = 5 LARGE AND 10 SMALL

THE BLUE COLOR IS DUE TO METHANE IN THE ATMOSPHERE.

URANUS HAS A MAGNETIC FIELD ABOUT 50 TIMES STRONGER THAN THAT OF EARTH.

IT DOES NOT HAVE AURORA LIKE JUPITER AND SATURN AS IT IS FURTHER FROM THE SUN.

URANUS HAS SOME NARROW RINGS – PROBABLY ROCKY COMPOSITION.

NEPTUNE

NEPTUNE IS SLIGHTLY SMALLER IN DIAMETER THAN URANUS, BUT HAS SLIGHTLY GREATER MASS.

DISTANCE FROM SUN = 30 AU

ROTATION = 16 HOURS

ORBIT = 165 YEARS

NEPTUNE IS THOUGHT TO HAVE A ROCKY CORE ABOUT 15 TIMES AS MASSIVE AS EARTH.

TILT ON AXIS = 50 degrees

NEPTUNE HAS A MAGNETIC FIELD SLIGHTLY LESS THAN THAT OF URANUS.

NEPTUNE HAS FAINT RINGS.

IT HAS 2 LARGE MOONS AND 6 SMALLER ONES.

THE LARGEST IS TRITON AND IS ABOUT THE SAME SIZE AS OUR OWN MOON.

TRITON HAS A THIN ATMOSPHERE OF MOSTLY NITROGEN AND POLAR ICE CAPS – ALSO NITROGEN.

PLUTO

PLUTO IS 2/3 THE SIZE OF OUR OWN MOON AND 1,200 TIMES FURTHER AWAY.

THIS MAKES IT VERY DIFFICULT TO SEE, EVEN WITH A TELESCOPE.

DISTANCE FROM SUN = 40 AU

ROTATION = 6 ½ DAYS ORBIT = 248 YEARS

PLANET DISTANCE FROM SUN

MERCURY 0.39

VENUS 0.72

EARTH 1

MARS 1.5

JUPITER 5.2

SATURN 9.5

URANUS 19.2

NEPTUNE 30

PLUTO 40

THERE IS A SCATTERED RING OF DEBRIS CONSISTING OF OBJECTS MADE MOSTLY OF ICES THAT EXTENDS FROM ABOUT 30 TO 50 AU.

THIS REGION IS CALLED THE KUIPER BELT.

SCIENTIST ESTIMATE THAT THERE MAY BE AS MANY AS 100,000 OBJECTS IN THE KUIPER BELT WITH DIAMETERS GREATER THAN 50 KM, BUT THE TOTAL DENSITY IS PROBABLY NOT GREATER THAN 1/10 THAT OF EARTH.

BEYOND THE KUIPER BELT, SCIENTIST BELIEVE THERE IS A SPHERICAL CLOUD OF DEBRIS KNOWN AS THE OORT CLOUD.

THIS EXTENDS FROM ABOUT 50,000 TO 100,000 AU OR 1 LY TO ABOURT 1.7 LY FROM THE SUN.

THIS REGION COULD CONTAIN UP TO 1 TRILLION ICY OBJECTS AND IS THOUGHT TO BE THE ORIGIN OF MOST COMETS.

The Sun's nearest known stellar neighbor is a red dwarf star called Proxima Centauri, at a distance of 4.3 light years away.

Our solar system is part of our home galaxy.

Our home galaxy is the Milky Way galaxy, a spiral galaxy of approximately 200 billion stars.

Edge on view of our galaxy.

Our solar system is about 28,000 light years from the center.

We’re rotating the center at a speed of 250 km/sec and complete one rotation every 220 million years.

THIS LITTLE PLACE WE CALL HOME

KEPLER’S SECOND LAW INTERACTIVE:http://highered.mcgraw-hill.com/sites/0072482621/student_view0/interactives.html#

KEPLER’S THIRD LAW INTERACTIVE:http://highered.mcgraw-hill.com/sites/0072482621/student_view0/interactives.html#