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SOLAR SYSTEM…AND BEYOND
A.S. E.1.1 – E.1.5
Monday, April 13, 2015
STRUCTURE OF OUR SOLAR SYSTEM


Kepler’s 1st Law: Planets will orbit in elliptical
orbits with the Sun at one of the focii
Eccentricity: a measure of how elliptical an
orbit is. Venus is the least eccentric planetary
orbit

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Most of the objects in the solar system follow a nearly
circular orbit—but are still ellipses
Note on distances: many distances in the solar
system are listed in terms of astronomical
units. The average distance from the Earth to
the Sun is 1 AU.

See diagram of elliptical orbits on p. 488 of purple
textbook…
MAJOR PLANETS—A RANKING OF
DIAMETER (SIZE)
Planet Name
Mercury
(smallest)
Mars
Venus
Earth
Neptune
Uranus
Saturn
Jupiter
(Largest)
DWARF PLANETS
i.e. Pluto, Ceres, etc.
 Those objects orbiting the Sun, but that have not
cleared their orbital pathway of other objects

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Many Kuiper Belt objects and asteroids are
considered Dwarf Planets
ASTEROIDS
Asteroid Belt located between Mars and Jupiter
 In a location that theoretically could have been a
planet, but…

Not enough debris left in the planetary disk at that
point to have gravitational force required to form
planet
 Jupiter was “greedy” 


Billions of asteroids—some as small as pebbles,
some 100 km + in diameter
COMETS
“dirty snowballs” or “snowy dirtballs”
 Frozen ammonia, carbon dioxide, water, methane…
 As they come closer to the sun, they sublimate, coma
increases in diameter, and solar wind pushes much of the
dust and gas in a direction pointed away from the sun

Both dust tail and ion tail
always point away from the sun
 Tails get longer as the comet
gets closer to the sun
 Orbits are HIGHLY elliptical

KUIPER BELT
Outskirts of solar system—beyond Neptune
 Pluto is technically part of the Kuiper Belt (one of
the closest objects from the Belt)
 Billions of Pluto-sized objects, and smaller, and
some potentially bigger (not detected…yet.)
 7.5 – 9.3 Billion miles from Sun

OORT CLOUD
Surrounds Solar
System—2 parts
 Inner Oort Cloud
disc shaped like
the Kuiper Belt
 Outer Region is
more spherical
 “home” of the
comets
 2000 – 100,000+
Earth Distances
(Astronomical
Units / AU) from
the Sun

STELLAR CLUSTERS

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Groups of closely-located stars that share a
common origin and are held together by a mutual
gravitational attraction
Globular Cluster

Thousands to hundreds of thousands of stars grouped
together in a roughly symmetrical, spherical shape
PLEIADES (“SEVEN SISTERS”)

•
•
•
Open (Galactic)
Cluster
Dozens to hundreds
of stars grouped
together
Not organized in a
symmetrical
arrangement
Pleiades is one of
the most commonly
recognized open
clusters
CONSTELLATION
“groups” of stars that
have been linked
together by Earthbound observers in
order to make
“pictures” in the night
sky
 The stars in a
constellation are very
rarely anywhere close
to each other

“BIG DIPPER” (URSA MAJOR)
LIGHT YEAR
A measurement of astronomical distances
 Equivalent to the distance that light, traveling in
a vacuum, will cover in 1 Earth year (365.25
days)

Conversion: How many meters is 1 ly?
 Conversion: How many meters is 1 AU?
 Conversion: How many AU is 1 ly?

APPARENT MOTION OF STARS (THROUGH A NIGHT)
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http://kids.britannica.com/eb/art-90838/A-person-standing-on-Earth-does-not-feel-the-motion