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The Solar System
Earth Science: Solar System
(20min)
The Solar System
• Matter that forms a system and shares a
gravitational force with the sun = solar
system.
– The sun, planets and all objects that revolve
around the sun make up our solar system.
– Extensive and covers a large territory
– Energy, from the sun, is in the form of radiation as
infrared waves.
Solar System Models
• Greek astronomers (A.D. 140) watched stars
move across the sky and charted their
unchanging patterns.
– Noticed 5 points of light wandered among the stars –
planets
• Planet = Greek for “Wandering Star”
– Ancient Romans named these 5 planets Mercury, Venus, Mars,
Jupiter and Saturn.
– Believed that Earth is at the center of the solar system
– Geocentric system
• Geo = Greek for “Earth”
Solar System Models
• Polish astronomer Nicolaus Copernicus (1500s)
believed the sun to be the center of the solar
system - heliocentric system.
– Helios = Greek for “sun”
• Galileo Galilei (1500-1600s) defended this idea
with two discoveries:
1. Jupiter has 4 moons revolving around it.
• Not everything in the universe revolves around Earth.
2. Venus goes through phases similar to Earth’s moon.
• This couldn’t happen with Earth being at the center.
Inertia and Gravity
• The planets revolve around the sun in a curved
path, orbit.
– What forces keep the planets in their orbits?
Inertia and Gravity
• The ability of an object to continue in a straight
line or remain stationary = inertia.
– Increase mass = increase inertia
• The force that attracts all objects toward each
other = gravity
– Mass and distance both affect gravity.
Gravitational pull
of sun.
Planet’s
Velocity
The Sun
• Came into being about 4.6 billion years ago
• Center of the solar system.
• The sun’s gravity is by far the most powerful
force in the solar system.
• All objects revolve around the sun.
• Contains 99.8% of the mass of the solar system
• Mostly Hydrogen (H) and Helium (He)
– Uses nuclear fusion to convert hydrogen into helium
• Will last for 10 billion years and is estimated to be 5 billion
years old right now.
• Burns at 15 million °C
The Planets
• There are a total of 8 planets that make up our
solar system:
–
–
–
–
–
–
–
–
Mercury
Venus
Earth
Mars
Jupiter
Saturn
Uranus
Neptune
Inner Planets: Terrestrial Planets
Outer Planets: Gas Giants
Inner Planet Characteristics
•
•
•
•
•
Closest to the sun
Composed mostly of rock
Small and Dense
Few to no moons
No rings
Mercury
Mars
Venus
Earth
Inner Planet Facts
Planet
Diameter
(km)
Rotation
(Earth
days)
Mercury
4,878
59
Venus
Earth
Mars
12,104
12,756
6,794
243
1
1.03
Distance Revolution Moons
from the
(Earth
Sun
years)
(km)
58,000,000
.24
0
108,000,000
150,000,000
228,000,000
.62
1
1.9
0
1
2
Mercury
• First planet closest to the sun
• Second smallest planet
• Thin to no atmosphere
– Due to the planets extreme temperature the
atmosphere heated to the point that it escaped.
• Most extreme temperatures of all the planets
– Day time = 430°C
– Nighttime = -170°C
Venus
• Second planet from the sun.
• Similar to Earth in size and mass
and is referred to as Earth’s twin.
• Also known as the “evening star” or
“morning star”
– Shines bright in western sky
• Atmosphere is thick and dense consisting mostly
of carbon dioxide (CO2) and sulfuric acid (H2SO4)
• Temperature is roughly 460°C
Earth & Mars
Earth
• Third planet from the sun.
• Is the only planet where life
exists at present time due to
oxygen and liquid water.
Mars
• The fourth planet from the sun.
• Called the “red planet”.
• Thought to once have running river systems.
• Has a thin atmosphere and clouds.
Outer Planet Characteristics
• Farthest from the sun.
• Composed mostly of gas - “gas giants”.
• Large in size - make up 99% of the mass of the
celestial bodies that orbit the sun.
• Several moons.
• Separated from the inner planets by an asteroid
belt.
Outer Planet Facts
Planet
Jupiter
Saturn
Uranus
Neptune
Diameter Rotation Distance from Revolution Moons
(km)
(Earth
the Sun
(Earth
days)
(km)
years)
142,800
.41
778,000,000
12
18
120,540
.43
1,427,000,000
29
18
51,200
49,500
.72
.67
2,871,000,000
4,497,000,000
84
165
20
8
Jupiter
• Fifth planet from the sun.
• Largest planet in the solar system.
– 300 times bigger than Earth.
• Consists mostly Hydrogen (H) and Helium (He)
• Known for its “Great Red Spot”, a storm similar
to a hurricane.
Saturn
•
•
•
•
Sixth planet from the sun.
Second largest planet
Known for its over 1000 rings
Consists mostly of Hydrogen (H) and Helium
(He)
• Least dense of the planets – less dense than
water (1g/mL).
Uranus & Neptune
Uranus
• The seventh planet from the sun.
• Looks blue due to its traces of methane and
ammonia.
• Axis is tilted at 90° making it look like it rotates on its side, or
from bottom to top.
Neptune
• The eighth and farthest planet
from the sun.
• Extremely fast winds, 1200mi/hr
• Looks blue due to its traces of
methane and ammonia.
What about Pluto?????
• Pluto is no longer considered the ninth planet of
our solar system but is now called a dwarf planet.
• Definition of a planet: an object that orbits the
sun and is large enough to have become round
due to the force of its own gravity. In addition, a
planet has to dominate the neighborhood around
its orbit.
– Pluto does not dominate its neighborhood and has an
untidy orbit.
Other Celestial Objects
• Three other celestial objects can be found in our
solar system besides the sun, moons and planets:
– Comets – chunks of ice and dust whose orbits are
usually very long and narrow ellipses.
• Unique in that they have long tails that trail behind the
comet itself.
– Halley’s Comet, 1986
» 76yr orbit = 2062 will be
its next sighting.
– Hale-Bopp, 1997
Other Celestial Objects
– Asteroids – too small and too numerous to be
considered planets
• Revolve around the sun between Mars and Jupiter in
the asteroid belt.
Other Celestial Objects
– Meteoroid – A chunk of rock or dust in space.
•
Usually come from comets or asteroids when they break
apart.
–
Upon entering Earth’s atmosphere friction make a meteoroid
burn up and produce a streak in the sky = meteor.
» If a meteor doesn’t burn up completely and hits Earth’s
surface it is called a meteorite.
• Consist mostly of iron (Fe) and nickel (Ni).
Chicxulub Crater, Yucatán Mexico
10 Biggest Asteroid Impacts