Download What is a Solar System?

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A star and all of the objects that travel in
orbit around it
The area of space that is influenced by the
gravity of a star
Our solar system is just one of many others.
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The Sun
Planets
Dwarf Planets
Satellites/Moons
Comets
Asteroids
Meteoroids
Distance and size NOT to scale
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All planets orbit the sun in almost-circular
elliptical orbits on approximately the same
plane (the ecliptic).
Dwarf Planets, comets, asteroids, and
meteoroids also orbit the sun
Most Satellites/Moons orbit planets (some
orbit dwarf planets or even asteroids)
Almost all planets, dwarf planets, and moons
rotate and revolve counter-clockwise
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In 2006, the IAU defined a planet as a
celestial body that:
◦ Is in orbit around the sun
◦ Has sufficient mass to assume a (nearly)
round shape
◦ Has cleared the neighborhood around its
orbit
Jovian Outer Planets
Terrestrial Inner Planets
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“Earth-like”
◦ Mercury
◦ Venus
◦ Earth
◦ Mars
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“Jupiter-like”
◦ Jupiter
◦ Saturn
◦ Uranus
◦ Neptune
Gas
Giants
Ice
Giants
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Closer to the sun
Relatively small size and mass as compared to
outer planets
Rocky surface
Craters present to some degree on all inner
planets
Feb. 2015 – NASA image
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Further from the sun
Very massive
Gas Giants and Ice Giants
Lower average density than terrestrial planets
All have rings
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2006 image from
Keck Observatory
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In 2006, the IAU defined a dwarf
planet as a celestial body that:
◦ Is in orbit around the sun
◦ Has sufficient mass that it assumes a
(nearly) round shape
◦ Has NOT cleared the neighborhood
around its orbit
◦ Is NOT a satellite
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Smaller than planets
Have “company” in their orbital areas
Can have moons
Most are located in
the Kuiper Belt, but
Ceres is in the
Asteroid Belt
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Bright spot?
More to come,
as Dawn mission
approaches
Ceres this
month
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A satellite (AKA-moon) is an object that
revolves around a planet or dwarf planet (or
an asteroid)
As of 2008, there are 176 confirmed moons
in our solar system
Most are located around the outer planets
Explorers’ Guide to the Solar System
16
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Many smaller objects also orbit
the sun
◦ Asteroids
◦ Comets
◦ Meteoroids
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Asteroids are small,
rocky, and irregular (up
to 1000 km)
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Sometimes called
“minor planets”
Most orbit in a region
between the orbits of
Mars and Jupiter known
as the Asteroid Belt
Combined, they would
be about half the size of
Earth’s moon
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An ice and rock core
(nucleus) that melts as
it approaches the sun
and gets blown into
space by solar wind
pressure (coma and
tail).
Highly elliptical orbits
originate in deep space
Kitt Peak telescope
image
of comet NEAT in 2004
(NASA, NOAO, NSF, T.
Rector, Z.
Levay and L.Frattare)
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On 12 November
2014, ESA's Rosetta
mission soft-landed
its Philae probe on
comet 67P/
ChuryumovGerasimenko
During the next phase
of the mission,
Rosetta will
accompany the comet
through perihelion in
August 2015
Image taken by Rosetta 165 km from the center of
Comet 67P, April 15, 2015
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Meteoroids are small
irregular grains of rock, most are asteroid pieces
and comet dust (up to a few meters in diameter)
◦ If they collide with Earth’s atmosphere, they
form visible streaks of light as they burn up
and are called meteors (shooting stars)
◦ If a meteor reaches Earth’s surface, it is then
classified as a meteorite
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Their location
◦ Meteoroid= space
◦ Meteor= Earth’s atmosphere
◦ Meteorite= Earth’s surface
Explorers’ Guide to the Solar System
24