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What we know about the Universe
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A celestial body is a natural object out in
space such as a planet, a moon, an asteroid, a
comet, or a star.
People made note of the movement of the
celestial bodies.
People would use celestial bodies the
measure the passage of time
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Patterns of stars in the sky
The people told stories of kings and queens,
heroes and villains, animals and mythical
creatures, and put them in the sky.
Characters from Greek and Roman
mythology make up most of the
constellations we use today
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(including the Big Dipper)
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-(including the Little Dipper)
cyclic paths
The sun appears to move across the ecliptic due to the earth movement around the
sun
 The moon also moves across the sky following the ecliptic on 28 day cycle.
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the planets revolve
around the Sun
 they move at
different rates along
the ecliptic.
 Mercury and Venus
are close to the Sun (
seen in the at dawn or
dusk)
 Outer planets can be
seen at all times
throughout the night
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Haley ‘s comet every 75-76 years
comets can orbit
in different
planes.
Different periods
(1986 to 2061)
Comet Hale-Bopp comes every 2520-2533 years ( 1997- 4527)
The are
constellations
only visible in the
winter.
 The are
constellations
only visible in the
summer.
 Orion is a winter
constellation
 Gemini is a
summer
constellation
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Aristotle (383–322 B.C.E.)
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A geocentric universe has Earth at
the centre and the Sun, Moon,
planets, and stars revolving around
it
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Ptolemy (83–168 C.E.)
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Aristotle’s model did not explain
all the observed motions
ie. Retrograde motion . A planet
appearing to move backwards in
the sky for a short time because
we pass the planet on the inside.
Ptolemy envisioned each planet
not attached directly to its
sphere,but attached to an offcentre wheel, which rotated as the
sphere turned.
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Nicolaus Copernicus (1473–1543),
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Copernicus’ model of a heliocentric
universe set the stage for other
scientists to better understand the
universe and to propose their own
theories based on his model.
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Galileo Galilei (1564–1642)
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First person to turn a small
telescope toward the heavens
He observed craters on the
Moon
spots on the Sun
four “stars” orbiting the planet
Jupiter (the moons of Jupiter)
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Galileo reasoned that
Venus could only have
phases if it orbited
the Sun
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Johannes Kepler (1571–1630)
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He could describe the motions of
the planets more accurately using
new technologies to make very
accurate observations, then
analyzing the data using
mathematics.
Kepler developed three laws of
planetary motion
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Sir Isaac Newton (1643–1727)
the most influential scientist who ever lived
developed three laws to describe and predict
motion (Laws of motion)
the first to show mathematically that the force
of gravity extends far beyond the surface of
Earth (Law of Gravitation)
These same laws govern the motion of stars
throughout the Milky Way galaxy.
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Stone Circles
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Ancient observatories for plotting the movement of celestial
bodies
Stonehenge in England
Bighorn Medicine Wheel
Wyoming, U.S.A.
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Astrolabe
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help them locate and predict the positions of the Sun, Moon,
and stars.
Measured angles in the sky
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Telescope an optical device that uses lenses to gather
and focus light to provide a magnified view.
Canada-France-Hawaii Telescope
Hubble Space Telescope
Galileo
Equivalent in angular size to a 65 mm tennis ball at a distance of 100 metres
Almost all of the 3,000 objects in the image are galaxies
We believe it is the same in all directions