Sun, Earth and Moon System
Its all about
Phases, Rotation and Revolution
WHY?
Why is it important to us to understand
the movements of the Sun, Earth and
Moon?
How would the history of mankind be
different if the knowledge of the celestial
bodies was never gained?
THE SUN
THE SUN
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The Sun is the primary
source of energy for all life
on earth.
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Composition: Hydrogen 91.2%, Helium - 8.7%,
Trace elements - 0.1%
Structure
Solar Properties
Photosphere
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The Sun is the most prominent feature in our
solar system.
It is the largest object and contains
approximately 98% of the total solar system
mass.
The Sun's outer visible layer is called the
photosphere and has a temperature of
6,000°C (11,000°F).
This layer has a mottled appearance due to
the turbulent eruptions of energy at the
surface called granules
Corona
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The corona is the outer part of the Sun's
atmosphere.
It is in this region that prominences appears.
Prominences are immense clouds of glowing
gas that erupt from the upper Chromosphere.
The outer region of the corona stretches far
into space and consists of particles traveling
slowly away from the Sun.
The corona can only be seen during total solar
eclipses.
Chromosphere
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The Chromosphere is above the photosphere.
Solar energy passes through this region on its way
out from the center of the Sun.
Faculae and flares arise in the Chromosphere.
Faculae are bright luminous hydrogen clouds which
form above regions where sunspots are about to
form.
Flares are bright filaments of hot gas emerging from
sunspot regions.
Sunspots are dark depressions on the photosphere
with a typical temperature of 4,000°C (7,000°F).
Core
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Solar energy is created deep within the core of the Sun.
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It is here that the temperature (15,000,000° C; 27,000,000° F)
and pressure (340 billion times Earth's air pressure at sea
level) is so intense that nuclear reactions take place.
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This reaction causes four protons or hydrogen nuclei to fuse
together to form one alpha particle or helium nucleus.
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The alpha particle is about .7 percent less massive than the
four protons.
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The difference in mass is expelled as energy and is carried to
the surface of the Sun, through a process known as
convection, where it is released as light and heat.
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Energy generated in the Sun's core takes a million years to
reach its surface.
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Every second 700 million tons of hydrogen are converted into
helium.
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In the process 5 million tons of pure energy is released;
therefore, as time goes on the Sun is becoming lighter.
Age
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The Sun appears to have been active for 4.6 billion years and
has enough fuel to go on for another five billion years or so.
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At the end of its life, the Sun will start to fuse helium into
heavier elements and begin to swell up, ultimately growing so
large that it will swallow the Earth.
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After a billion years as a red giant, it will suddenly collapse
into a white dwarf -- the final end product of a star like ours. It
may take a trillion years to cool off completely.
EARTH
The Earth
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Third planet from the Sun
Oblate sphere
elliptical orbit
70% water
Rotates on its imaginary axis counterclockwise every 24 hours
or 1 day
Revolves around the sun every 365 days or 1 year.
78% nitrogen
21% oxygen
1% argon, neon, carbon dioxide, neon, & krypton
The sun heats the Earth unevenly, making the poles cold and
the tropics hot
The tropics face more directly toward the sun
The poles are at an angle to the sun which makes them colder
Seasons change
Weather changes
Earth Rotation
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Earth rotation refers to the spinning of our planet on its axis.
The Earth's surface moves at the equator at a speed of about 467 m
per second or slightly over 1675 km per hour.
If you could look down at the Earth's North Pole from space you
would notice that the direction of rotation is counter-clockwise.
One rotation takes exactly twenty-four hours and is called a mean
solar day.
The Earth’s rotation is responsible for the daily cycles of day and
night.
At any one moment in time, one half of the Earth is in sunlight, while
the other half is in darkness.
The edge dividing the daylight from night is called the circle of
illumination.
The Earth’s rotation also creates the apparent movement of the Sun
across the horizon.
Rotation
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The movement of the Earth about its axis is known as rotation. The direction of
this movement varies with the viewer’s position. From the North Pole the
rotation appears to move in a counter-clockwise fashion. Looking down at the
South Pole the Earth’s rotation appears clockwise.
Earth Revolution
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The orbit of the Earth around the Sun is called an Earth
revolution.
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The Earth's orbit around the Sun is not circular, but oval or
elliptical .
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This celestial motion takes 365.26 days to complete one cycle.
causes the Earth's distance from the Sun to vary over a year.
causes the amount of solar radiation received by the Earth to annually vary by
about 6%.
On January 3, perihelion, the Earth is closest to the Sun (147.3
million km).
The Earth is farthest from the Sun on July 4, or aphelion (152.1
million km).
The average distance of the Earth from the Sun over a one-year
period is about 149.6 million km.
Revolution
Position of the equinoxes, solstices,
aphelion, and perihelion relative to the
Earth's orbit around the Sun.
Tilt of the Earth's Axis
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The ecliptic plane can be defined as a two-dimensional flat
surface that geometrically intersects the Earth's orbital path
around the Sun.
The Earth's axis is not at right angles to this surface, but inclined
at an angle of about 23.5° from the perpendicular.
4 important dates: June solstice, September equinox, December
solstice, and March equinox.
Circumstance responsible for the annual changes in the height of
the Sun above the horizon.
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The angle of the Earth's axis in relation to the ecliptic plane and the
North Star on these four dates remains unchanged.
The relative position of the Earth's axis to the Sun does change
during this cycle.
It also causes the seasons, by controlling the intensity and duration
of sunlight received by locations on the Earth.
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During the two equinoxes, the circle of
illumination cuts through the North
Pole and the South Pole.
On the June solstice, the circle of
illumination is tangent to the Arctic
Circle (66.5° N) and the region above
this latitude receives 24 hours of
daylight.
The Arctic Circle is in 24 hours of
darkness during the December
solstice.
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The Earth’s rotational axis is tilted 23.5° from the red line drawn perpendicular
to the ecliptic plane. This tilt remains the same anywhere along the Earth’s
orbit around the Sun. Seasons are appropriate only for the Northern
Hemisphere.
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Annual change in the position of the Earth in its revolution around the Sun.
View of the Earth from a position in space that is above the North Pole at the summer solstice, the winter solstice, and the two
equinoxes.
The position of the North Pole on the Earth's surface does not change.
Its position relative to the Sun does change and this shift is responsible for the seasons.
During the June solstice, the area above the Arctic Circle is experiencing 24 hours of daylight because the North Pole is tilted
23.5 degrees toward the Sun.
The Arctic Circle experiences 24 hours of night when the North Pole is tilted 23.5 degrees away from the Sun in the
December solstice.
During the two equinoxes, the circle of illumination cuts through the polar axis and all locations on the Earth experience 12
hours of day and night.
Summer and Winter Solstice
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During the June solstice the Earth's North Pole is tilted 23.5 degrees
towards the Sun relative to the circle of illumination.
Keeps all places above a latitude of 66.5 degrees N in 24 hours of
sunlight, while locations below a latitude of 66.5 degrees S are in
darkness.
The North Pole is tilted 23.5 degrees away from the Sun relative to
the circle of illumination during the December solstice.
All places above a latitude of 66.5 degrees N are now in darkness,
while locations below a latitude of 66.5 degrees S receive 24 hours of
daylight.
Autumnal and Vernal Equinox
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On September 22 or 23, also called the autumnal equinox in the
Northern Hemisphere, neither pole is tilted toward or away from the
Sun .
In the Northern Hemisphere, March 20 or 21 marks the arrival of the
vernal equinox or spring when once again the poles are not tilted
toward or away from the Sun.
Day lengths on both of these days, regardless of latitude, are exactly
12 hours.
The Moon
The Moon
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Earth's satellite
Composition: Iron - magnesium silicates
Rotational period: about 27 days
Orbital period: 27.3 days
elliptical orbit
Craters
Highlands
Maria
Regolith
Water ice
Lunar Surface
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Craters: caused by asteroids and meteorites
Highlands: formed by asteroid impacts / lava
flows
Maria: created by basaltic lavas from asteroid
impacts generating heat to melt rock
Regolith: caused by asteroid and meteor
impacts; igneous rocks, breccia,
glass beads and dust
Water ice: comet bombardment
CRATERS
HIGHLANDS
Maria
REGOLITH
WATER ICE
LUNAR FORMATION
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Impact of earth with Mars size
planetismal
Ripped from Earth's mantle - similar in
composition
Phases of the Moon
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Lunar phases are
created by changing
angles (relative
positions) of the
earth, the moon and
the sun, as the moon
orbits the earth.
Lunar Eclipses
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Caused by the Earth's shadow being cast
upon the moon's surface as the Moon passes
behind the Earth and the Sun is positioned
on the other side of Earth - called the
ecliptic.
The umbra is the inner, cone shaped part of
the shadow, in which all of the light has been
blocked.
The outer part of Earth's shadow is the
penumbra where only part of the light is
blocked.
Occurs every 6 months
The Geometry of a Lunar Eclipse
Solar Eclipses
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Caused by shadow of the Moon being
cast upon the Earth as it passes
between the Sun and Earth
Occurs every once every 18 months
Tides
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Tides are the regular rising and falling of Earth's
surface water in response to gravitational attraction
from the Moon and Sun.
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The Moon's gravity causes the oceans to bulge out
in the direction of the Moon.
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the Moon's gravity is pulling upwards on Earth's
water, producing a high tide.
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On the other side of the Earth, there is another high
tide area, produced where the Moon's pull is
weakest.
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As the Earth rotates on its axis, the areas directly in
line with the Moon will experience high tides.
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Each place on Earth experiences changes in the
height of the water throughout the day as it changes
from high tide to low tide.
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There are two high tides and two low tides each tidal day.
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Spring tide: occurs when the Sun and Moon are in line.
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happens at both the new moon and the full moon.
The Sun's gravity pulls on Earth's water, while the Moon’s gravity
pulls on the water in the same places.
The high tide produced by Sun adds to the high tide produced by
the Moon.
So spring tides have higher than normal high tides.
occurs in a 24-hour period.
Neap tide: occurs when the Earth and Sun are in line but the
Moon is perpendicular to the Earth.
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This happens when the moon is at first or last quarter moon
phase.
the pull of gravity from the Sun partially cancels out the pull of
gravity from the Moon, and the tides are less pronounced.
Neap tides produce less extreme tides than the normal tides.
This is because the high tide produced by the Sun adds to the low
tide area of the Moonand vice versa.
So high tide is not as high and low tide is not as low as it usually
might be.
SPRING TIDE
Earth
NEAP TIDE