Transcript Astronomy - cloudfront.net

Environmental Science
 Scientists
have been
researching the sky for
almost 3000 years!
 Early
astronomy was
centered in Greece.
Famous Greek
Astronomers
Aristarchus
first proposed
the
heliocentric
model, but no
one believed
him.
 Retrograde
motion is when the
planet appears to stop, reverse its
direction for a time and then
resume the initial, eastward
motion.
 Retrograde
motion cannot
happen! Why?
Modern Astronomy uses
natural laws as opposed to
religion or philosophy to
determine astronomical
theories.
The Scientists involved in
the modern Astronomical
theory were from a
variety of European
countries.
 Determined
that the earth is a
planet and that it rotates.
 Also
proposed a heliocentric
solar system.
Brahe made observations of
Mars and made instruments
with which to view the skies.
Kepler determined the laws of
planetary motion and that the
orbits of planets are elliptical.
 States
that the square of the
length of time that it takes a
planet to orbit the sun (orbital
period) is proportional to the cube
of its mean distance to the sun.
 Huh?
2
T
=
3
d

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For example:
Mars has an orbital period of 1.88 years. The
square of 1.88 is 3.54 (T2). The cube root of
3.54 is 1.52. So the distance from Mars to the
sun is 1.52 AU.
The AU stands for astronomical unit is the
average distance between the earth and sun
is about 150 million km.
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Jupiter’s four moons;
That planets are circular disks;
That Venus has phases like our moons;
That the surface of our moon is not smooth;
The Sun’s sunspots.
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Is a Scientific theory that every body in the
universe attracts every other body.
This attraction is proportional to the mass
and inversely proportional to the square of
the distance between their centers of mass.
This means: the greater the mass, the
greater the gravity. The smaller the distance
the greater the gravity.

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This force (called gravity) decreases
with distance (inversely proportional).
The larger the mass, the larger the
gravitational pull.
The moon has a strong enough pull
that it causes pull that it causes tides,
but a satellite does not have a large
enough pull to have a measurable
effect on Earth.