27.2 - The Moon
Exploring the Moon
• Astronomers have learned much about the Moon from
observations with telescopes
• The first step to reaching the moon was in 1957, when the
Soviet Union launched the first artificial satellite, Sputnik 1
Rocketing into space with
technology
• Before sending people into space, scientists sent unpiloted
spacecraft, or probes, into space to gather information and to see
what dangers lay ahead.
• The Russians developed the R-7 rocket to launch the first satellite,
Sputnik I, in 1957
Rocketing into space with
technology
• One month later, they launched the first space traveller, a dog
named Laika
Rocketing into space with
technology
• Then, in 1961, they launched the first human space traveller,
Yuri Gagarin
Rocketing into space with
technology
• In 1969, two American astronauts, Neil Armstrong and Edwin
"Buzz" Aldrin, became the first humans to land on the Moon
The Lunar Surface
• The moon may look very
bright to us but it is actually
very dark!
• The ALBEDO of the Moon,
which is the amount of
sunlight it reflects is very
small (7%)
• Earth’s albedo is about 31%
• It can be very hot (127°C)
and very cold (-173°C)
Man in the Moon
• Lunar highlands are heavily cratered regions of the Moon that
are light in colour and mountainous
• Other regions called MARIA (mare) are dark smooth plains
• Maria have few craters
Lunar Craters
• Craters on the Moon are called IMPACT CRATERS, which were
formed when objects in space crashed into the lunar surface
• When these objects hit the surface, material blasted out and
fell back to the surface and formed EJECTA
• Some of these craters have large trails of EJECTA called RAYS
Lunar Craters
• Ways are visible as light
coloured streaks
• Most maria are smooth,
they do have a few
scattered craters and
RILLES
• Rilles are valleylike
structures that might be
collapsed LAVA TUBES
Lunar Properties
• Our moon is very unique when compared to other moon
because of its solid and rocky body
• Most other moons are icy compositions and quite smaller in
size
• Our moon is one of the largest moons compared to the radius
and mass of the planet it orbits
Lunar Properties
• The moon is made up of many minerals similar to that of Earth
• The highlands are mostly Lunar Breccias, which are rocks that
form from fusion of smaller rock during impacts
• The Maria is predominantly basalt but contain no water
History of the Moon
• Radiometric dating of rocks from the highlands indicates the
moon age to be between 3.8 and 4.6 billion years (same as
Earth)
• Scientists believe the moon was heavily bombarded during its
first 800 million years
• As a result, surface rocks were heated and broken creating
ground up rock called regolith
• Regolith varies in depth but can be several meters in thickness
Layered Structure
• Scientists infer from seismic data that the moon has a layered
structure like the earth
• This consists of the crust, upper mantle, lower mantle and core
• Similar to the Earth, the core is iron and the lower mantle is
partly molton
• The upper mantle is solid
Formation of maria
• Lava filled in large impact basins which created the dark
smooth plains of the maria
• Flowing lava in the maria scarred the surface with rilles
• Rilles are tubes that having flowing lava beneath the surface,
underground streams
• Maria have remained relatively smooth because there has
been fewer impacts
Formation of Maria
• Scientists hypothesize that the far side of the moon (craters)
does not have any maria because of its thick crust which
restricted the flow of lava
• The near side has a much smoother surface
Tectonics
• The moon has
MOONQUAKES!
• These moonquakes
occur once a year and
are strong enough to
cause dishes to fall out
of a cupboard
• Even though the moon
has moonquakes, it is
not tectonically active
• This means the moon
has no active volcanoes
Formation
• Several theories have been proposed to explain the moon’s
unique properties
• The widely accepted theory is the IMPACT THEORY
Impact Theory
• According to the
impact theory, the
moon formed as a
result of a collision
between Earth and a
Mars-sized object
about 4.5 billion years
ago when the solar
system was forming
• This explains why the
moon’s crust is so
similar to the Earth’s
in chemical
composition and the
small amount of iron
in the core
Impact Theory
The Origin of the Moon
The Birth of the Moon