Astronomy Ch. 2

Navigate the ocean, planting, and harvesting
Why did ancient cultures use the stars?
Stonehedge
Salisbury plain in England, built in 2800-1100 BC, largest stones were 50 tons, used as calendar/almanac
Big horn medicine wheel
In Wyoming, used by plains Indian tribes as calendar, set up to show rising and setting times of the sun and stars
Caracols temple
In Mexico, built by Mayans in 1000AD, windows line up with the sunrise/set of the solstices and equinoxes, rising and setting of Venus (god they worshipped) can be observed
Ancient chinese
Collected scientific data during the dark ages (5-10th centuries) they documented supernova in 1054AD
Islamic Astronomers
Developed trig, came up with terms zenith and azimuth and named many stars: vega, Rigel, Betelgeuse
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Cosmology
The study of the workings of the universe in the largest scale
Greeks
Who observed in the night sky and thought the earth was the center? sun, moon, and stars, 5 planets: Mercury, Venus, earth, Mars, Jupiter, Saturn. Planets were called wanderers
Retrograde
Greeks thought planets motion was _______
Greeks
Who observes that planets move with respect to fixed stars. Because brightness and speed of planets changed, they thought the motion was retrograde
Mercury and venus
Which planets are inferior planets
Inferior planets
Planets that orbit closer to the sun than to earth
Mars, Jupiter, Saturn
Which planets are superior planets
Superior planets
Planets whose orbits are farther away from the sun
Prograde
Motion is forward, east
Retrograde
Motion is backwards, west
Aristotle
Taught that the universe is geocentric. The sun, planets, moon, and stars orbit the earth. Had more influence, belief until the 16th century
Aristarchus
Said everything orbits the sun and that earth rotated on an axis, correct but not widely accepted. His ideas weren’t really published until copernicus
Epicycle
Each planet, sun, and moon moves in small circle
Deferent
The center of each epicycle moves around earth
Ptolemy
In order for aristotles theory to work, this philosopher developed his theory of planetary motion
Ptolemaic model
Geocentric model with epicycles and deferents, lasted until the 16th century, Ptolemaic picture lasted 13 centuries with 80 epicycles, Renaissance changed it
Nicholas copernicus
Re-introduced idea of sun centered solar system. Idea first presented by Aristarchus during Aristotle’s time. Writings banned for 200 years
Copernican model
Sun is the center, moon orbits the earth, planets orbit the sun. This model wasn’t popular. Written in Latin so only educated could read and understand it. Also went against teachings of Catholic Church- God would only make a earth centered universe
Galileo
Who is the father of experimental science
Galileo
Modern astronomy is attributed to _____
Telescope
What did Galileo build without ever actually seeing
Sun spots
Galileo looked at the sun and documented that the sun rotates and has _____
Jupiter
Which planet did Galileo document has moons
Venus
Which planet did Galileo see that goes through phases, which helped support a sun centered solar system
Bradley and bissel
Which two astronomers helped strengthen the copernican system after Galileo
Bradley
Discovered the aberration of starlight
Bissel
Discovered stellar parallax to help support the copernican system
Kepler
Who worked with Tycho Brahe and took the data he collected from his teacher when he died?
Tycho Brahe
Who was Keplers teacher?
Tycho Brahe
collected astronomical data and was known as the greatest observational astronomer
Kepler’s first law
orbital paths of planets are elliptical with the sun at one focus
ellipse
flattened circle, orbits are known as these
focus
one of 2 points on the major axis (diameter) of the ellipse
major axis
the long axes or diameter of the ellipse
semi major axis
half of the long/major axis (radius)
Eccentricity
measure of how flat the ellipse is
1
eccentricity of a line
perihelion
a planets closest approach to the sun
aphelion
a planets furthest approach to the sun
Kepler’s second law
an imaginary line connecting the sun to any planet sweeps out equal areas of the ellipse in equal time intervals (the speed changes)
period
time needed for the planet to complete one revolution around the sun (orbital ____)
Kepler’s Third Law
the square of the planet’s orbital period is proportional to the cube of the semi-major axis; p2/au3 = 1au = astronomical unit
mercury and pluto
which planets have the most eccentric orbits
greater its orbital period
the further a planet is from the sun …
astronomical unit
distance of the Earth from the Sun
Triangulation
(old method) use transit of Mercury and Venus across the sun. Measure from different locations on Earth and apply parallax
Radar
modern method to find dimensions of the solar system
radio detection and ranging
what does radar stand for?
the law of gravity
what is newtons most famous law?
3 laws of motion, law of gravity, calculus
what are the newtonian mechanics
first law
every body continues at a state of rest or movement in a straight line unless acted upon by an outside force
force
the change in original motion of an object
inertia
the tendency of an object to continue in the same direction and speed unless acted upon
mass
object’s inertia = ______ = amount of matter
velocity
speed and direction
acceleration
rate of change in velocity
second law
when a force acts on a body with mass, its acceleration, a=F/m
third law
to every action there is an equal and opposite reaction
gravity
a continuous force
inverse square law
gravitational force is inversely proportional to the square of the distance
gravitational force
attractive force exerted on objects by other objects with mass
Newton
Who corrected Keplers laws saying that they the planets do NOT have the sun in the direct center of their orbits (the center of their orbits is the center of the mass)?
center of mass
planet and sun orbit the _____
escape speed
the speed needed to escape orbit
unbound
an object exceeds escape speed
gravitational field
created by gravity between 2 objects
9.80 m/s2
What is the constant for gravity?