Transcript Stars and Galaxies - Burke County Public Schools

Although Pluto is no longer considered a
planet, it is still part of the solar system.

Solar Nebular Theory
•
A nebula is a cloud of gas and/or dust
in space.
•
According to the nebular theory, the
sun and planets formed from a rotating
disk of dust and gases.
•
Planetesimals are small, irregularly
shaped bodies formed by colliding
matter.
Planetary Composition, Distance
from the Sun, and Melting Point
• INNER PLANETS
– also known as
the terrestrial
planets
– dense, small,
have solid rocky
surfaces, metal
cores
• OUTER PLANETS
– also known as the Jovian Planets
– less dense, large, gaseous, thick
atmosphere
To remember the order of the
planets, just remember this
sentence…
“My Very Eager Mother
Just Served Us Noodles”
Solar System Models
• geocentric model:
model of the solar system
that states that the Earth
is the center of the solar
system
– believed until 1600’s
• heliocentric model: model
of the solar system that
states that the sun is the
center of the solar system
and the planets revolve
around it
• The path a planet follows
around the sun is called its
orbit
Kepler’s Laws of Planetary Motion
• 1st law : planets orbit the sun
in a path called an ellipse
• 2nd law: planets move fastest
when they are closest to the sun
in their orbits
• 3rd law: the farther away a
planet orbits, the longer the
planet takes to revolve around
the sun
• revolution: movement of the
Earth around the sun
– takes 365.24 days (1 year)
• rotation: spinning of Earth on its
axis
– takes 24 hours (1 day)
– rotates counterclockwise
the Earth is tilted 23 ½ °on its
axis. Either the Northern
Hemisphere or Southern
Hemisphere tilts towards the sun
• hemisphere that tilts towards
the sun has summer (more
direct sunlight
• hemisphere that tilts away from
the sun  has winter (less direct
sunlight)
• summer solstice: longest sunlight
hours of the year-June 21st-first day
of summer
• winter solstice: shortest sunlight
hours of the year- Dec. 21st- first day
of winter
• spring equinox: equal amounts of
day/night hours- March 21st- first day
of spring
• fall equinox: equal amounts of
day/night hours- Sept. 21st- first day
of fall
Other Objects in the Solar
System
• comet: composed of dust,
rock, frozen water, and gas
1. nucleus: glows by reflected sunlight
2. coma: hazy cloud that surrounds the
nucleus
3. tail: gas and dust that always points
away from the sun
Halley’s Comet
Hale-Bopp
Comet
• asteroid: solid, rock-like mass,
irregular in shape
• orbit the sun- most orbit between
Mars and Jupiter in the asteroid
belt
• meteoroid: rock or icy fragment
moving through space
– can be large as a boulder or as
small as sand
•meteor:
light made by
meteoroid as it passes
through Earth’s atmosphere
stone
meteorite
iron
meteorite
stony-iron
meteorite
• if they strike the Earth, they
form impact craters (this is
rare!)
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reviewing. After you choose a topic it will
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