Download Earth, Moon, and Sun System

Earth, Moon, and Sun
System
Earth’s Magnetic Field
Earth has a
magnetic field
that protects us
from harmful
radiation from
the sun.
Earth’s Magnetic Field
Earth’s magnetic field is:
•Concentrated at two ends
of an imaginary magnetic
axis running from Earth’s
north magnetic pole to its
south.
•Tilted about 11.5 degrees
from the geographic axis
Earth’s Magnetic Field
Earth’s magnetic
field:
•Changes slowly
over time.
•Called the
magnetosphere
•Responsible for
auroras.
Earth’s Magnetic Field
What are auroras?
•The
magnetosphere
deflects harmful
radiation from the
Sun, a stream of
particles called solar
wind.
Earth’s Magnetic Field
What are auroras?
•These particles from
the Sun produce
charged particles in
Earth’s atmosphere
that spiral along
Earth’s magnetic field
lines towards the
magnetic poles and
collide with atoms in
the atmosphere.
These collisions cause
atoms to emit light.
Earth Orbits the Sun
Earth’s orbit is slightly
elliptical.
An ellipse is like a
slightly flattened circle
or egg-shaped.
Earth As a Planet
Earth is the only planet
with characteristics that
make it possible for life
as we know it to
survive.
Earth as a Planet
Earth resembles
Venus more than
any other planet
in:
•Size
•Both have
atmospheres with
carbon dioxide
Time and Seasons
Humans have used
movements of Earth,
the Moon, and the
Sun to measure time
for thousands of
years.
•Earth makes a
complete rotational
turn once in about 24
hours.
•Earth’s actual
rotation is 23 hours,
56 minutes, and 4
seconds.
Time and Seasons
Revolution Measures
Years
•The time that it takes to
make a complete
rotation or orbit around
the sun is 365 days
which is our Earth year.
Time and Seasons
Why do seasons change?
•They change primarily due
to the tilt of the Earth on its
axis in relationship to the
sun (changes in the angle
of sunlight hitting certain
parts of Earth).
•In short, Earth’s seasons
are influenced by Earth’s
rotation, revolution, and tilt
of its axis.
Time and Seasons
Why do we have more
daylight in summer
than winter?
•The hemisphere of the
Earth that is tilted
toward the Sun
receives more hours of
daylight…another
reason it is warmer in
the summer.
Time and Seasons
Equinoxes and
Solstices
Two times a year,
the sun is directly
over the Earth’s
equator. This is
called an equinox.
Time and Seasons
During an equinox, the
number of daylight
hours equals the
number of nighttime
hours all over the
world.
•These occur around
March 20th or 21st, and
September 22nd or
23rd.
Time and Seasons
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The solstice is the point at
which the Sun reaches its
greatest distance, north or
south of the equator, and it
appears to “stand”, or stop
moving. This occurs on June
21st or 22nd, and December 21st
or 22nd.
•During summer solstice, there
are more hours of daylight than
during any other day of the
year, and during winter solstice,
it is the shortest daylight day of
the year.
Movement of the Moon
It takes 27.3 days
for the Moon to
revolve once
around earth and
two more days for
the Moon to line up
with Earth and the
Sun again, thus a
complete lunar
phase takes 29.5
days (a synodic
month)
Movement of the Moon
The same side of
the moon always
appears toward
Earth because it
takes 27.3 days to
rotate once on its
axis, the same
amount of time it
takes to revolve
once around Earth.
How does the moon affect
Earth?
TIDES
Tides are caused by a
giant wave produced
by the gravitational
pulls of the Sun and
the Moon.
The actual wave is only
1-2 m, but has a
wavelength of
thousands of
kilometers.
How does the moon affect
Earth?
TIDES
Even though it is smaller
than the sun, the moon has
a greater effect on tides
than the sun because it is
closer.
How does the moon affect
Earth?
TIDES
When the moon and
sun line up, high tides
are much higher and
low tides are much
lower. This is called a
spring tide.
How does the moon affect
Earth?
TIDES
When the moon and
sun are at right angles
to each other, the high
tide is not as high and
the low tide is not as
low, producing a neap
tide.
Phases of the Moon
The moon
“shines” because
it is reflecting
sunlight from its
surface.
Moon phases are
the changing
appearances of
the Moon as seen
from Earth.
Phases of the Moon
New Moon
•Moon is between the
Earth and the Sun.
•Cannot be seen
(except during a special
alignment)
Phases of the Moon
Waxing Phases
•Lighted portion that we
see appears to be
larger each night.
•Said to be in the
waxing gibbous phase
until it reaches the full
moon phase.
Phases of the Moon
Waning Phases
•The lighted portion that
we see appears to be
smaller each night.
Eclipses
Solar Eclipse
•Occurs when the moon
moves directly between
the Sun and Earth and
casts a shadow on part of
Earth.
•The darkest portion of
the Moon’s shadow is
called the umbra.
Eclipses
Solar Eclipse
•The lighter
shadow cast on
Earth’s surface
is called the
penumbra.
Eclipses
Lunar Eclipse
•Occurs when
Earth’s shadow
falls on the moon.
Moon’s Surface
Craters, Maria, and
Mountains
•Many depressions
(craters) were
formed by
meteorites,
asteroids, and
comets striking the
surface of the
moon.
Moon’s Surface
Maria
•Dark-colored relatively
flat regions on the
Moon’s surface.
Regolith
•Debris on the Moon’s
surface.
Moon’s Interior
The moon’s interior is
believed to have a
crust, upper mantle,
lower mantle, and a
core.
Moon’s Origin
Capture Theory
The moon was captured by Earth’s gravity.
Binary Accretion Theory
The moon condensed from the same material that
formed the Earth.
Moon’s Origin
Fission Theory
A glob of molten
material was ejected
from Earth while it was
still in its molten stage.
Moon’s Origin
Giant Impact Theory
•A Mars sized object
collided with Earth.
•The cores of the 2 bodies
combined and settled
toward the center of the
larger object.
•Gas and debris
condensed into a large
mass forming the moon.