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Astronomy
Famous Astronomers
• Ptolemy : Earthcentered universe
• Copernicus : Suncentered universe
Ptolemy: Geocentric
Copernicus: Heliocentric
Newton
• Sir Isaac Newton introduced the theory of
gravity. That all objects in the universe are
attracted to other objects.
• This idea explained why all objects orbit
the most massive object in the solar
system.
Gravity Controls
EVERYTHING
Orbits Because of Gravity
• An orbit is a fall that is the same arc as the
object it is falling toward.
Moon Orbit
Seasons
• As the earth tilts the
seasons change.
Why do we have seasons?
The Moon
The Moon controls the tides on Earth
TIDES
• What are tides?
– The periodic rise and fall of the
sea level under the gravitational
pull of the moon
• Tides are one of the most
reliable phenomena in the
world. As the sun rises in the
east and the stars come out at
night, we are confident that the
ocean waters will regularly rise
and fall along our shores.
Moon Tide
• The Moon’s gravity exerts a
strong pull on Earth.
• The water bulges outward
as Earth and the Moon
revolve around a common
center of mass.
• The moon’s gravity pulls on
the earth, and pulls the
water towards it. The water
moves up into a slight bulge
on the side of the earth that
faces the moon.
The Sun Tide
• The sun’s pull can heighten
the moon’s effects or
counteract them, depending
on where the moon is in
relation to the sun.
Spring Tides
• Spring tides are especially
strong tides (they do not have
anything to do with the season
Spring). They occur when the
Earth, the Sun, and the Moon
are in a line. The gravitational
forces of the Moon and the
Sun both contribute to the
tides. Spring tides occur during
the full moon and the new
moon.
Neap Tides
• Neap tides are especially weak
tides.
• Moon & Sun are perpendicular
to each other.
• Moon & the Sun’s gravity cancel
each other out.
Tidal Range
• The tidal range is the difference
between the level of the ocean at high
tide and low tide.
Phases of The Moon
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
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
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
New Moon
The lighted side of the Moon faces away
from the Earth. This means that the Sun,
Earth, and Moon are almost in a straight
line, with the Moon in between the Sun
and the Earth. The Moon that we see
looks very dark
New Moon
First Quarter Moon
The right half of the Moon appears lighted
and the left side of the Moon appears
dark. During the time between the New
Moon and the First Quarter Moon, the part
of the Moon that appears lighted gets
larger and larger every day, and will
continue to grow until the Full Moon.
First Quarter Moon
Third (Last) Quarter Moon
Sometimes called Third Quarter. The left
half of the Moon appears lighted, and the
right side of the Moon appears
dark. During the time between the Full
Moon and the Last Quarter Moon, the part
of the Moon that appears lighted gets
smaller and smaller every day. It will
continue to shrink until the New Moon,
when the cycle starts all over again.
Third Quarter Moon
Full Moon
The lighted side of the Moon faces the
Earth. This means that the Earth, Sun,
and Moon are nearly in a straight line, with
the Earth in the middle. The Moon that we
see is very bright from the sunlight
reflecting off it.
Full Moon
There are also four other
phases of the Moon
sometimes used.
Waxing Crescent Moon
This Moon can be seen after the New Moon,
but before the First Quarter Moon. The
crescent will grow larger and larger every
day, until the Moon looks like the First
Quarter Moon.
("Waxing" means increasing, or growing
larger.)
http://btc.montana.edu/ceres/html/birthdayphases.html
Waxing Crescent Moon
http://btc.montana.edu/ceres/html/birthdayphases.html
Waxing Gibbous Moon
This Moon can be seen after the First
Quarter Moon, but before the Full
Moon. The amount of the Moon that we
can see will grow larger and larger every
day.
("Waxing" means increasing, or growing
larger.)
http://btc.montana.edu/ceres/html/birthdayphases.html
Waxing Gibbous Moon
http://btc.montana.edu/ceres/html/birthdayphases.html
Waning Gibbous Moon
This Moon can be seen after the Full Moon,
but before the Last Quarter Moon. The
amount of the Moon that we can see will
grow smaller and smaller every day.
("Waning" means decreasing, or growing
smaller.)
http://btc.montana.edu/ceres/html/birthdayphases.html
Waning Gibbous Moon
http://btc.montana.edu/ceres/html/birthdayphases.html
Waning Crescent Moon
This Moon can be seen after the Last
Quarter Moon and before the New
Moon. The crescent will grow smaller and
smaller every day, until the Moon looks
like the New Moon.
("Waning" means decreasing, or growing
smaller.)
http://btc.montana.edu/ceres/html/birthdayphases.html
Waning Crescent Moon
http://btc.montana.edu/ceres/html/birthdayphases.html
Phases of
the Moon
Eclipse
• When a shadow of a celestial body falls
onto another an eclipse occurs.
Solar Eclipse
• Occurs when the moon passes between
the earth and the sun.
Lunar Eclipse
• Occurs when the moon Earth passes
between the Sun and the Moon.
Lunar Eclipse Solar Eclipse
Full
New
at Night
Daytime
Movement of Stars
• Stars appear to move because the earth
moves.
Movement of Stars
• Stars change places in the sky depending
on where earth is on its revolution around
the sun.
Magnitude
• Apparent Magnitude is how bright a star
appears from Earth.
• Absolute magnitude is how bright the star
actually is.
Constellations
• Constellations are sections of the sky that
contain recognizable star patterns.
The Big Bang Theory
The Big Bang
• The theory that the entire universe began
with one large explosion.
How They Think it Happened
• The contents of the universe were
compressed into a very dense sphere.
• It exploded and continued to move
outward.
• Then it all came together to form galaxies.
Galaxies
• Spiral
• Elliptical
• Irregular
The Milky Way
• The Spiral Galaxy in which we live.
Solar System
The Solar System
Inner Planets
•
•
•
•
Mercury – closest to the sun
Venus – hottest due to greenhouse effect
Earth – the only planet with life
Mars – strong evidence for water
Outer Planets
•
•
•
•
Jupiter – largest planet
Saturn – largest rings made of icy particles
Uranus – rotation is 90 degrees of earth’s
Neptune – atmosphere of visible clouds