Transcript THE SOLAR SYSTEM UNITS OF MEASURMENT IN ASTRONOMY

THE SOLAR SYSTEM
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
3031 mi
7512 mi
7926 mi
4221 mi
5% of
Earth
800o F
95% of
Earth
900o F
1.3 x 1025
pounds
56o F
11% of
Earth
- 20o F
ATMOSPH
ERE
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
DIAMETER
MASS
AV. TEMP.
* 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
VENUS
EARTH
MARS
JUPITER
SATURN
URANUS
NEPTUNE
PLUTO
0.39
0.72
1
1.5
5.2
9.5
19.2
30
40
ELIPTIC PLANE AND INNER PLANETS
PLANETS AND JUPITER
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