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Earth & Environmental Science
UNIVERSE
•The universe is commonly defined as
the totality of everything that exists,
including planets, stars, galaxies, the
contents of intergalactic space, and all
matter and energy.
•According to the prevailing scientific
model of the universe, known as the
Big Bang, the universe expanded from
an extremely hot, dense phase
GALAXIES
Shapes
Our Galaxy: Milky Way
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The Milky Way galaxy is the spiral galaxy we call
home, as do roughly 100 billion other stars.
The Sun is far from the center of the Galaxy,
halfway to the edge of the Galaxy along the Orion
spiral arm.
The center of the Milky Way As with most other
galaxies, there is a super massive black hole there.
Not only does it try to eat anything that goes near
it, the area around it is a good place for new stars
to form.
Our location
The Sun
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The Sun is the star at the center of the Solar System.
It weighs nearly 330,000 times as much as Earth!
Sun Facts Continued..
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It is made up of mostly hydrogen and helium gases.
It is 93 million miles from Earth.
It takes 8 minutes and 19 seconds for light to travel
from the Sun to the Earth.
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Energy is produced by Fusion (joining of nuclei)
The Sun’s Energy
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Electromagnetic Energy- type of energy radiated
by the Sun in the form of waves.
Waves- a way for energy to travel from one point
to another.
Long wavelength = Low energy.
Short wavelength = High energy.
Wavelength and Visible Light
What happens to the energy once it reaches the
Earth’s atmosphere?
-it is taken in as HEAT!
Heat
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Heat can be transferred by three methods:
Radiation
Convection
Conduction
Radiation
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Radiation occurs when the Sun’s energy is
transferred to the Earth through waves.
The Earth absorbs the energy as heat, warming the
planet.
Kitchen Example: Microwave
Convection
Convection is the transfer of heat by the physical
movement of the heated medium itself.
 It occurs in a cyclical motion: hot medium goes up,
cold medium goes down.
 Occurs in liquids and gases only.
 Kitchen Example:
- Oven or teapot
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Conduction
Conduction is heat transfer as a result of direct
contact with heated medium without movement of
the medium.
 Conduction occurs
through TOUCH.
 Kitchen Example:
Stovetop
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Does the Sun’s energy affect Earth?
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Photosynthesis- Plants use the
Sun’s energy to make food,
which helps them grow.
Sun’s energy uses continued…

Solar Power- We use the Sun’s energy to power our
homes through Solar Panels.
Why the sun
makes life on
earth possible
EARTH’S MOVEMENTS
Who orbits what?
• Planets in the solar system orbit the Sun?
• Actually they orbit the “center of mass”
– Called the “barycenter” of the solar system
• Barycenter has “smooth” path through galaxy (but
Sun/planets “wiggle”)
– Earth/Moon system also has a barycenter
The revolution of the Earth around
the sun
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Takes 365.25 days or
one year.

Leap year
Seasons
What two things cause the difference in the seasons?
1.
The angle of the sun’s rays
2.
The length of the days
There are two kinds of rays from the Sun:
1.
Direct- occurs when Earth is tilted toward the Sun
2.
Indirect-occurs when Earth is tilted away from the Sun
In the Summer, we get the direct rays from the sun and the days
are longer. (But we are farther away from the Sun)
In the Winter, we get indirect rays from the Sun and the days
are shorter. (But we are closer to the Sun)
Earth's Precession
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Earth's polar axis precesses very slowly over a
period of about 23,000 to 26,000 years. The term
precession simply refers to a change in the direction
of the axis of a rotating object. As this occurs, the
pole of the Earth inscribes an arc in the heavens
called the precessional arc. Earth's pole aligns with
different pole stars throughout its precessional
period. Polaris is Earth's current north-pole star.
Earth's ~25,000-year precessional cycle is also
referred to as "Earth's Great Year."
Nutation:(Latin nutare, "to nod")
•Nutation is, in astronomy, a small irregularity
in the precession of the equinoxes
•Nutation superimposes a small oscillation,
with a period of 18.6 years and an amplitude
of 9.2 seconds of arc, upon this great slow
movement.
•The cause of nutation lies chiefly in the fact
that the plane of the Moon's orbit around the
Earth is tilted by about 5°from the plane of
the Earth's orbit around the Sun.
Rotation
What does Rotation mean?
Rotation occurs when something is spinning around an axis.
What are some examples of things that rotate?
Tops, Ballerinas, Figure skaters, cyclones, Tornadoes, a merry-goround, Earth
How do we know that the Earth rotates?
1.
Star trails- trails made with time exposure, circular paths that
occur because the planet is moving and not stationary.
2.
Winds curve because of the Earth’s rotation.
3.
Ocean currents curve clockwise in the northern hemisphere, and
counterclockwise in the southern hemisphere.
4.
The movement of a pendulum. It does not actually move, it is the
Earth moving that causes the pendulum to appear to change the
direction of its swing.
Night and Day
What causes night and day?
The rotation of the Earth
 The side of the Earth that is facing the sun has daylight, the side of
the Earth away from the sun has night.
 It takes 23 hours 56 minutes and 4.1 seconds (24 hours) for the Earth to
complete one rotation.
 The Earth is tilted on it’s axis at a 23.5 degree angle.
 The Earth’s tilt in the direction of the North Star.
What is another name for the North Star?
Polaris
 This tilt is what causes our days to get longer in the summer and
shorter in the winter.
 Because of the Earth’s rotation the sun appears to rise in the east and
set in the west.
Summary
What is the difference between rotation and revolution?
Rotation occurs when an object spins around an axis.
Revolution occurs when an object spins around another object.
What type of movement causes night and day?
The Earth’s rotation
What type of movement causes the change of seasons?
The Earth’s revolution- the angle of the sun, and the length of the day.
How do we know that the Earth Rotates?
Star trails, pendulum swings, ocean currents, wind currents
MOON
PHASES
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The moon revolves or
orbits the Earth once
every 29 days.
We all ways see the
same side of the moon
because the moon
rotates and revolves at
about the same speed.
Tides
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As the moon travels
around the earth and
as they, together,
travel around the sun,
the combined
gravitational forces
cause the world’s
oceans to rise and
fall, which is called
tide.
Half of the Moon is always lit up by the sun.
As the Moon orbits the Earth, we see
different parts of the lighted area.
http://www.nasm.si.edu/apollo30th/moontheater/phasepage2.html
The revolution of the Moon around the Earth
makes the Moon look as if it is changing
shape in the sky.
http://btc.montana.edu/ceres/html/birthdayphases.htm
This is caused by the
different angles
from which we see
the lighted part of
the Moon's
surface. These are
called "phases" of
the Moon.
http://btc.montana.edu/ceres/html/birthdayphases.htm
http://www.niehs.nih.gov/kids/
lunar/why_phases.gif
The Moon passes through four major shapes
during a cycle that repeats itself every
29.5 days. The phases always follow one
another in the same order:
New moon
First quarter
Third quarter
Full moon