The First Science. First observed and used by cultures like the Chinese, Egyptians, and Babylonians...
If you can't read please download the document
The First Science. First observed and used by cultures like the Chinese, Egyptians, and Babylonians Used for planting crops, tracking hunting migrations
First observed and used by cultures like the Chinese,
Egyptians, and Babylonians Used for planting crops, tracking
hunting migrations Used to track the Sun, Moon, and the 5 known
planets. Chinese tracked Halleys comet for 10 centuries. Also
observed and recorded guest stars. We know these as normal stars,
which are usually too faint to be visible, which increases its
brightness as it explosively ejects gases from its surface, a
phenomenon we call a nova or supernova (novus = new). Ancient
Astronomy
Slide 4
Occurred in Greece from 600 BC 150 AD Used Geometry and
Trigonometry to measure the distances between as well as the size
of the Sun and Moon. The Greeks created both geometry and
trigonometry! Golden Age of Astronomy
Slide 5
Geo = Earth Centric = center Stated that Earth was a motionless
sphere at the center of the universe in which everything else
orbited. Earths rotation not demonstrated until 1851. Geocentric
Model
Slide 6
Created in 141 AD. Was a model that accounted for observable
motions of celestial bodies. Noticed planets had a retrograde
motion and accounted for it with this model. Results from the
combination of the motion of the Earth and the planets own motion
around the sun. Mars looked like it went backwards because Earth
orbits the Sun faster than Mars. Ptolemys Model
Slide 7
Slide 8
Used circular orbits around the Earth with smaller circular
orbits following them called epicycles. Ptolemys Model (cont.)
Slide 9
Slide 10
Much of the accumulated knowledge of astronomy was lost around
the 4 th century during the fall of the Roman Empire when libraries
were burned and destroyed. One step forward, two steps back
Slide 11
After the decline of Greek and Roman civilizations the center
of the study of astronomy moved to the Middle East. Specifically
Baghdad. Ptolemys model had been translated into Arabic. Arabic
astronomers expanded the then current star catalog and divided the
sky into 48 constellations. Became the foundation of our present
day constellation system. Saving Science!!
Slide 12
Ptolemys model had been translated into Arabic. Arabic
astronomers expanded the then current star catalog and divided the
sky into 48 constellations. Became the foundation of our present
day constellation system. Ptolemys model not reintroduced into
Europe until the 18 th century.
Slide 13
Break from philosophical and religious views. Took almost 13
centuries after Ptolemy to make any major advances in astronomy in
Europe. 5 major scientists contributed to what we know about
astronomy. Modern Astronomy
Slide 14
The idea of Earth being a sphere was lost. Convinced that Earth
was a planet, just like the other 5 then known planets. Daily
motions of celestial bodies explained more simply by a rotation
Earth. Nicolaus Copernicus (1473-1543) Poland
Slide 15
Constructed the Heliocentric model. Helio = Sun (Greek) Centric
= center Still used circular orbits and smaller epicycles like
Ptolemy. ~~Follower Giordano Bruno was burned at the stake in 1600
for refusing to denounce Copernican theory. Nicolaus Copernicus
(cont.)
Slide 16
Had an observatory near Copenhagen, Denmark where he used
pointers to measure locations of celestial bodies for 20 years.
Didnt use telescopes because he didnt have one! No one did.. Tried
to disprove Copernicus using stars. Couldnt observe the apparent
shift shown with rotation The apparent shift of stars is called
stellar parallax, which is used to measure distances between stars.
Tycho Brahe (1546-1601) Danish
Slide 17
Created 3 laws of planetary motion (1609- 1619). He used these
to account for the motion of Mars. Led him to find that the orbit
of Mars is elliptical not circular and its speed varies based on
its location during its orbit. Johannes Kepler (1571-1630) Czech
Republic
Slide 18
The path of each planet around the Sun, while almost circular,
is actually an ellipse, with the Sun at one focus. Keplers First
Law of Planetary Motion
Slide 19
Each planet revolves so that an imaginary line connecting it to
the Sun sweeps over equal areas in equal intervals of time. This
law or equal areas geometrically expresses the variations in
orbital speeds of the planets. Keplers Second Law of Planetary
Motion
Slide 20
The orbital periods of the planets and the distances to the Sun
are proportional. The orbital period is measured in Earth years,
and the planets distance to the Sun is expressed in terms of Earths
mean distance to the Sun called the astronomical unit (AU) (1 AU
150 millions or 93 million miles). The planets orbital period
squared is equal to its mean solar distance cubed. Keplers Third
Law of Planetary Motion
Slide 21
Slide 22
Keplers laws support Copernicus theory Still didnt determine
the forces that act to produce planetary motion. Johannes Kepler
(cont.)
Slide 23
Supported Heliocentric model. Used telescopes for astronomy
after hearing about a Dutch lens maker who had devised a system of
lenses to magnify objects. He built many of his own and was able to
magnify x30 Galileo Galilei (1564-1642) Italy
Slide 24
5 Major Discoveries 1: Jupiters 4 largest satellites (moons).
2: Planets are circular disks (like Earth) rather than points of
light. 3: Venus exhibits phases like the moon showing that is must
orbit around the Sun, not Earth. Galileo (cont.)
Slide 25
4: The moons surface is not smooth glassy sphere, instead it
has craters and plains (he thought plains might be bodies of water)
5: The sun has sunspots which were areas of darker regions caused
by slightly lower temperatures. These were also tracked and
estimated a rotational period of the Sun to just under a month.
Galileo (cont.)
Slide 26
Formalized the concept of inertia, the first law of motion.
Determined the force that keeps the planets from going in a
straight line out in to space; Gravity. Formulated and tested the
law of universal gravitation. Everybody in the universe attracts
every other body with a force that is proportional to their masses
and inversely proportional to the square of the distance between
them. Sir Isaac Newton (1642-1727) England
Slide 27
Slide 28
Rotation = 1 day Revolution = 1 year Earth rotates as it
revolves around the sun. Earths orbit is an ellipse Earths
Movement
Slide 29
Perihelion = Earth is closest to the sun. About 91 million
miles away from sun. Northern Hemisphere pointed away from sun
makes is our winter (January) Aphelion = Earth is furthest from the
sun. About 95 million miles away from sun. Northern Hemisphere
pointed towards the sun makes is our summer (July) Axial tilt is
the reason for the seasons!!
Slide 30
Equinoxes and Solstices determined by the circle of
illumination. Equinoxes 2 per year Vernal (spring) March 20
Autumnal (fall) September 24 12 hours of day and night at every
latitude. Earth/Sun Relationships
Slide 31
Solstices 2 per year Winter Solstice (Dec 22) Winter for
northern hemisphere Northern hemisphere tilted away from sun Occurs
during perihelion. Summer Solstice (Jun 22) Summer in northern
hemisphere Northern hemisphere tilted towards the sun. Occurs
during aphelion. Earth/Sun Relationships (cont.)
Slide 32
Tides daily changes in the elevation of the ocean surface.
Easiest ocean movement to observe other than waves. Were not
explained until Sir Isaac Newton showed that there is a mutual
attractive force between two bodies (ex: Earth and Moon)
Earth/Sun/Moon Relationships
Slide 33
Slide 34
Moon causes bulge of water on side nearest the moon because of
gravitational forces. Creates a equal sized bulge on the opposite
side of the Earth. The Suns tide-generating effect is only about
46% that of the moon. Tides
Slide 35
New and Full moons Sun and Moon are aligned and their forces
are added together. The combined gravity causes higher high tides
and lower low tides. These are called Spring tides. Tides
(cont.)
Slide 36
Slide 37
First and Third Quarter moon phases. Moon and Sun act on right
angles and each partially offset the influence of the other. Daily
tidal range is less. These are called Neap tides. Tides
(cont.)