Transcript The Sun-Earth-Moon System

Earth Science
Chapter 27
Sections 1, 2, 3
Chapter 27
Section 1
 Electromagnetic
Radiation:
• Consists of electric and magnetic disturbances
traveling through space as waves.
 Electromagnetic
Spectrum:
• The wavelength and frequency of
electromagnetic radiation.

Electromagnetic
Radiation is classified
by wavelength.
• Distance from crest to
crest.

It is also classified by
frequency.
• The number of waves or
oscillations that pass
through a point in one
second.
• See p. 764
 Hz
– Hertz
• A unit equal to 1 cycle
per second
 Scientists
choose
their tools based on
the type of radiation
they want to study in
space.
p. 765
Give us the ability to
observe
electromagnetic
wavelengths beyond
what a human can
detect
 Aperture: the diameter
of an opening where
light is let in

• Human eye- 7 mm
• Telescope- 10 m

Benefits:
• Larger aperture than eye
• Can collect object too
dim for the eye to detect
 Eye only views objects for
1/10 of a second. Lenses
can stay open for hours to
collect more light

Tools used with
satellites
• Photometer
 Intensity of visible light
• Spectrophotometer
 Different wavelengths of
radiation
REFRACTING TELESCOPE


Use lenses to bring light
into focus
First telescopes
REFLECTING TELESCOPE


Use mirrors to bring light
into focus
Used by most astronomers
because mirrors can be
made larger than lenses
 Infrared
and ultraviolet radiation can be
focused with mirrors- reflecting
telescope
 X-Rays can’t be focused by normal
mirrors
 Gamma rays can’t be focused at all
 Radio
telescope:
 Collects longer
wavelengths
 Uses a large dish
antenna
 Reflects waves to a
single point
 A receiver collects
the signal and
converts it to electric
signals
 Interferometry
• Uses images from
several telescopes to
produce a single
image
• Scientists get a
detailed image with
the same resolution as
one large telescope
with a dish as large as
the distance between
the telescopes
 Instruments
in space collect data with our
Earth’s atmosphere blurring the images.
 Orbits
Earth every 97
minutes
 Obtains sharp visible
light images
 James Webb
Space
Telescope (planned
for 2013)
• Observe the infrared
range
 Sent
directly to the bodies to collect data
 Robotic probes:
• Spacecraft that can make close up observations
or collect information
• Cassini spacecraft
 Observed Saturn’s rings and moons
• Mars Reconnaissance Orbiter
 Used high resolution cameras to search for signs of
life
• New Horizons
 Launched toward Pluto and beyond with visible,
infrared and ultraviolet light cameras
Cassini
Mars Reconnaissance
Orbiter
New Horizons
 In
order to pursue more advanced human
spaceflight, scientists need to study:
• The effects of weightlessness on humans, plants,
and other phenomenon.
• The effects of radiation
 The
Space Shuttle program allows
scientists to study short term effects
 Longer
term effects need to be studied
on space stations
• International Space Station
 A multicountry space station
Chapter 27
Section 2
 First
explored with
telescopes
 Most information was
gained by probes
and sending men to
the moon
Lunar
Prospector
Clementine
 1957
Soviet Sputnik
• First satellite
 1961 Yuri
A. Gagarin
• First human in space
 1961
Alan B. Shepard, Jr.
• First American in space during Project Mercury
 Project
Gemini
• First two person crew in space
 1969
Apollo I1
• Neil Armstrong first human on the moon.
 Lunar
surface is dark
 Albedo: the percentage of incoming
sunlight that its surface reflects
• About 7%
• Earth’s Albedo is around 31%
 Moon
has no atmosphere to absorb heat
so its surface is hot (Varying
temperatures
• Light side: 127˚ C
• Dark side: -173 ˚ C
 Lunar
Highlands
• Heavily cratered
regions of the moon
• Light colored
 Maria
• Dark smooth plains
with few craters
 Impact
craters
• Objects have crashed
into the moon
 Ejecta
• The material blasted
out of the craters
 Rays
• Trails of ejecta that
radiate from the crater
 Rilles
• Meandering valley-
like structures
• Might be collapsed
lava tubes
 One
of the largest moons
 Solid rocky body
 Composed of mostly silicates
• Similar to Earth
 Highlands
• Rocks formed by the fusion of smaller pieces of
rock during impacts
 Maria
• Predominately basalt (volcanic) but with no
water
 Radiometric
dating
• 3.8-4.6 bya
 Heavily
bombarded during the first 800
million years
 Breaking and heating of surface formed a
layer of ground up rock
 Regolith- the fine layer of ground up rock
 Depth varies with location
 Crust
• Varies in thickness
• Thickest on the far
side that faces away
from Earth
 Upper
Mantle- solid
 Lower Mantle- molten
 Core- solid iron
 During
bombardment
• Lava filled the impact
basins
• Left dark smooth
plains
• Fewer maria on the far
side because the crust
is thicker and the lava
was too far under the
surface
 Moon
experiences about one
moonquake per year
 Strong enough to shake plates from a
cupboard
 Not much seismic activity
 Several
theories
 Impact theory- widely accepted
• Collision with a Mars shaped object and Earth
4.5 bya
• Parts of the fractured Earth flew into space
• Over time the orbiting objects came together to
form the moon.
• This explains the similarities to the composition
of the moon and the Earth
Chapter 27
Section 3
 Daily
rotation
• Causes the Coriolis
effect
 Day
Length
• 1 solar day is on
revolution on Earth’s
axis
• 24 hours
 Earth
revolves around the sun in a
elliptical plane
 Earth’s
tilt is
approximately 23.5˚
relative to the ecliptic
 Earth’s axis remains
fixed in space
 When Northern
hemisphere is toward
the sun the Southern
hemisphere is away
from the sun
A
solstice occurs
when the sun is at its
farthest distance from
the equator
 Summer solstice
brings the longest
day of the year and
winter solstice brings
the shortest
 Summer
solstice in
North America• Note the rays are
strongest in the
Northern portion of
the globe
• Rays are weakest in
the southern portion.
This is their winter
solstice.
 Earth’s
axis is
perpendicular to the
sun.
 Days and nights are
equal length
 Occur in spring and
fall
 Waxing
• The increasing visible
light starting with the
new moon
 Waxing crescent, first
quarter and waxing
gibbous
 Waning
• The decreasing visible
light starting at the full
moon
 Waning gibbous, third
quarter, waning crescent
 When
the moon orbits Earth the same
side faces it.
 The moon rotates exactly one time as it
goes around the Earth
This is synchronous rotation