# Astronomy Quiz 1

### 48 terms by sltorres

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### Milky Way

Our galaxy which contains 200 billion stars

### Light Year

the distance light will travel in one year

### constellations

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

### Sirus

brightest star in the sky

### Asterisms

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

### Rotate

Earth rotates on its axis

### Revolve

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.

### Latitude

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

### Longitude

Verticial coordinates

### Prime Merdian

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

### Latitude in the sky=

Declination or DEC

vernal equinox

### longitude=

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

21.5 degrees

### Ecliptic

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

### Precession

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

### Parallax

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

### Aratosthenes

Greek scientist who found the cirumference and radius of the earth

traveling west to east

traveling east to west

### Aristotle

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

### Ptolemy

used epicycles and defferents believed in geocentric system

### Deferents

the orbit path around the earth

### epicycle

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

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

### Kepler

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

### Force

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

### accleration

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

Example: