Planet Revolution

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Planet Revolution
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The Movement of the Solar System
? Rotation
Rotation is the turning, or spinning, of a
body on its axis.
Measurements for rotation
1. Mean solar day is the time interval from one
noon to the next, for Earth about 24 hours, for
Mars its about 24.5 hours
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The Movement of the Solar System
? Revolution
Revolution is the motion of a body, such as a
planet or moon, along a path around some point in
space.
Perihelion is the time in January when Earth
is closest to the sun.
Aphelion is the time in July when Earth is
farthest from the sun.
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The Movement of the Solar System
? Earths Axis and Seasons
The plane of the ecliptic is an imaginary
plane that connects Earths orbit with the
celestial sphere.
Because of the inclination of Earths axis to
the plane of the ecliptic, Earth has its yearly
cycle of seasons.
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Orbits of the Planets
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Planetary Data
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The Movement of the Solar System
? Revolution and Rotation
Revolution, the motion of a body around the
sun, applies in the case of Earth and Mars
Perihelion and Aphelion can be used when
discussing the revolutions of other planets
around the sun as well.
Length of Revolution and Rotation Although
Mars has a period of revolution that is only
about 37 minutes longer than Earths, it takes
Mars 687 days to revolve around the sun!
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23.2 The Terrestrial Planets
? The Martian Atmosphere
The Martian atmosphere has only 1 percent of
the density of Earths.
Although the atmosphere of Mars is very thin,
extensive dust storms occur and may cause the
color changes observed from Earth.
? Surface Features
Most Martian surface features are old by Earth
standards. The highly cratered southern
hemisphere is probably 3.5 billion to 4.5 billion
years old.
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Mars
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23.2 The Terrestrial Planets
? Water on Mars
Some areas of Mars exhibit drainage patterns
similar to those created by streams on Earth.
Images from the Mars Global Surveyor indicate
that groundwater has recently migrated to the
surface.
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Water on Mars