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Milky Way

Our galaxy which contains 200 billion stars

Light Year

the distance light will travel in one year


star pictures drawn in the sky by ancient civilizations. there are 88 in all


brightest star in the sky


things that look familiar but are part of a constellations and not one themselves. Examples= big and little dipper

Celestial Sphere

A sphere that encompassed the globe where every star was plastered to that and it was believed that this sphere moved. This ancient belief was an attempt to understand the night sky and which doesn't really exist


Earth rotates on its axis


earth revolves around the sun

Celestial Poles

Projecting the earth's coordinates into the sky (latitude and longitude)

Alpha and the greek alphabet

The brightest star in the constellation is always referred to as alpha followed by beta etc.


horizontal coordinates that are added 10 degrees when going north about the equator where its zero and subtract 10 degrees going south


Verticial coordinates

Prime Merdian

The "zero line" in longitude which goes through Greenwich, England

Latitude in the sky=

Declination or DEC

prime meridian=

vernal equinox


referred to in hours called right ascension (RA)

Solar day

a day according to the sun which equals 24 hours. Longer because it takes into account that we are revolving around the sun as well rotating on earth's axis. this difference is one of 4 minutes

Sidereal Day

a day measured by the stars= 23 hours and 56 minutes which is the true measure of rotation

Reason for seasons

= the tilt of the earth's axis

winter solstice (December 21st)

when the sun is tilted fartherest away from the sun. This produces the shorest days and nights

Summer solstice (June 21st)

when the sun is in the sky for the longest and at the highest

why is it hot in the summer?

because the sun is high in the sky and stays out longer

Cold in winter?

because the sun is low in the sky and stays out for the shortest period

Vernial equinox

spring time occurs on march 21st and the sun is in the sky equal amount of time that it isn't

Automnal equinox

fall time occurs on september 21st

Earth's tilt

21.5 degrees


path way of the sun which passes through 13 costallations which is where we get our zodiac signs from.


sun moves this way in the sky as well which is a wobble of the earth much like a spinning top. this wobble that has taken place over 26,000 years which has made our zodiac sign change and it is not what we thought it was when it was made.

Triangulate ideology

how we measure "x" a method to measure the distance of the stars from earth


measure stars by using the baseline of the Earth. Tells us how much something is from us in the sky . has to be close in order to work. if there is a small parallax than the object is far away. if large parallax than the object is close


Greek scientist who found the cirumference and radius of the earth


traveling west to east


traveling east to west


believed in geocentric (earth centered) universe. Also believed in uniform circular motion orbiting the earth in a uniform motion.


used epicycles and defferents believed in geocentric system


the orbit path around the earth


the planets orbit around themselves to explain the movements of the planets and why they move backwards and change brightness

Occam's Razor

the simplest explanation is almost always the correct explanations

Aristarchus of samus

he believed that the sun at the which is called heliocenteric and that the earth is on an axis

Nicholas cupurinus

rediscovered aristarchus of samus ideas

Cupurincan revolution

realization that earth is not the center of the univerese and everything traveled around the sun

Retrograde motion

when we pass planets that are further away than us on their own orbit that seem to "back-up"

Galieo Galei

"father of experimental science" conducted experiments through a telescope he created


A german scientist who created the Law's of planetary Motion

Astronomical unit (Au)

the distance between the earth and the sun. if you know how fast a planet is going around the sun you can determine how far away it is

Sir issac newton

three laws of motion and law of gravity= newtonian mechanics


As mass goes up accleration goes down; as mass goes down accleration goes up


rate of change of the velocity of an object speeding up, slowing down or change of direction

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