Transcript ASTRO EXAM AFTERNOON Review

Heliocentric Model
 Sun-centered
Geocentric Model
 Earth-centered
 True, but not well accepted  False, but assumed true by
at first.
many people initially.
1. ORBITS ARE
ELLIPTICAL (SUN @
ONE FOCUS POINT)
2. DURING THE YEAR, A
PLANET MOVES FASTER
WHEN IT’S CLOSER TO
THE SUN.
The planet sweep out
the same area in
equal periods of time
3. PLANETS THAT ARE
CLOSER TO THE SUN
MOVE FASTER THAN
PLANETS FARTHER
FROM THE SUN
…Mercury is faster
than Uranus…
1. Inertia
An object in motion will continue
to move at a constant speed and
in a straight line, unless acted
upon by an outside force.
-Things keep doing what they do.
2. Gravity
All objects attract all other
objects using gravity.
- The larger the mass, the stronger the
gravitational pull.
-The farther apart the two objects are,
the weaker the gravitational pull.
•List and describe the three motions of Earth.
ROTATION= spinning on
Earth’s axis. Creates day &
night. 24 hour period.
Related Vocab: SPHEROID.
…Earth is a bit wider @ equator than
from pole-to-pole.
Revolution / Orbit = motion along a path around
some point in space, such as around the Sun.
1 Year Period.
•List and describe the three motions of Earth.
Precession = Axis sweeps
a cone-shaped area.
26,000 Year Period.
Precession
Rotation
•List and describe the three motions of Earth.
Nutation = due to tidal forces,
the axis “shimmies” between
23°-26° as it precesses.
18.6 Year Period.
Today,
Earth’s axis is
tilted @
roughly 23.5°
BARYCENTER
Center of mass between
two objects.
http://en.wikipedia.org/wiki/Barycentric_coordinates_(astronomy)
↑Click This Link ↑
Galaxy, solar system, star, planet
Rotating nebula cooled and
contracted to form the sun
in the center… this is 99% of
the original nebular
material.
The remaining 1% continued
orbiting the new sun, and
eventually clumped
together to form planets.

Basically, everything orbits
everything else.
All objects rotate.
Moons orbit planets.
Planets orbit stars. (=solar system)
Solar systems orbit the center of
their galaxy.
 Galaxies orbit in groups.
 Galactic groups orbit the universe.
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How does this picture relate? 

Sun makes various forms of energy.
 (Gamma, X, UV, Visible, Infrared, Micro, TV/Radio)

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All of these move at the speed of light, but with
different amounts of energy (related to wavelength).
All of these travel to Earth via RADIATION.

SHORT WAVES =
HIGH FREQUENCY =
HIGH ENERGY
 Gamma Rays
 X-ray
 Ultraviolet (UV)
 Visible Light
 Infrared (heat)
 Microwaves
 Radio/TV

LONG WAVES =
LOW FREQUENCY =
LOW ENERGY

Frequency = number of
waves passing a given
point in a unit of time

Wavelength = length of
space it takes for a wave
to repeat itself.
Long Wavelength = ______frequency
LOW
= ______
LOW energy
Short Wavelength = ______frequency
= ______
HIGH energy
HIGH

White light is a mixture of colors

Seven hues: red, orange, yellow
green, blue, indigo & violet

Wavelength determines the
color of a beam of light

Prism splits beam because light
rays of different wavelengths
are bent (refracted)

Red- Bent the least; Violet- Bent
the most

Light behaves as a WAVE (discussed already) or
as a PARTICLE (photon)

Photon = particles of light that can push matter

Force photons exert is called radiation pressure
 What the “solar wind” is made of.
Light given off by stars
has many colors
 The light appears white to
us, but when a prism is
used, the colors separate
into a specific spectrum.
 The spectrum shows what
gases make up the star.

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The apparent change in wavelength of light
that occurs when the object is moving toward
or away from the Earth.
Ambulance Siren:
Approach observer: High pitch
Move away from observer: low pitch
BLUE SHIFT
RED SHIFT
Object approaching earth
Object moving away
from earth
Light waves are
compressed (pushed
together)
Light waves are
expanded
Wavelengths appear
shorter (blue end of
spectrum)
Wavelengths appear
longer (red end of
spectrum)
Using the spectroscope, astronomers can
determine whether a particular object is moving
toward Earth or away from Earth
Larger Doppler shifts indicated higher speeds and
smaller Doppler shifts indicate slower speeds.
B
R
B
R
Remember, the greater the amount of shift,
the faster the star is moving!
Helium
Helium slightly red shifted. Moving away slowly.
Helium more red shifted. Moving away even faster!
FISSION:
• Happens in nuclear power reactors
• LARGE elements BREAK UP form
smaller atoms elements
• Energy is released (heat)
FUSION:
• happens on the sun & other stars
• SMALL elements COMBINE to form
large elements
• Energy is released (heat, photons,
light)
brief outbursts of solar photons
release enormous amounts of
photons & energy (UV, Radio, XRay radiation)
 Ejects fast moving photons,
strengthening the solar wind


 can endanger space crews &
satellites
 Can strengthen auroras on Earth

Earth’s magnetic field protects
us from the effects of these
photons.
Earth's axis is tilted 23.5°.
-In the Northern Hemisphere's summer, we're
tilted TOWARD the sun (direct heating = hotter)
-In the Southern Hemisphere's summer, we're
tilted AWAY from the sun (indirect = colder)
SEASONS are all about how energy hits the Earth's surface...
Is it efficiently heating our surface?
Or is it inefficiently heating our surface?
Seasons are caused by the TILT OF EARTH’S AXIS,
NOT by how close we are to the sun
Our
Atmosphere
filters out much
of the
dangerous
HIGH ENERGY
wavelengths
to protect us.

Caused by the gravitational pull
of the MOON (and the sun).
SPRING TIDE = Earth-MoonSun are all lined up in a straight
line, so Moon & Sun are both
pulling oceans in same
direction.
 NEAP TIDE = E-M-S are at a 90°
angle, so Moon & Sun are
counteracting each other.

Magnetic field that
surrounds earth and
protects us from a lot
of the sun's harmful
radiation
-causes auroras!
VOCAB:
aurora, solar wind, magnetic field
(magnetosphere), photons
Equator is hotter
than the Poles
because the sunlight
is more direct there.
1. Land heats & cools
more rapidly than
water.
2. Land gets to greater
extremes in
temperature than
water.
…Which would be
Wilmington, which
would be Charlotte?
Photosynthesis is
the basis for all life
to exist.
The sun’s energy is
converted by plants
into chemical energy
that other organisms
use for food.