Chapter 2 - Part 1 Flashcards
On the horizon is east and west on the left or right?
East is on the right and west in on the left
On the sky is east and west on the left or right?
East is on the left and west is on the right
What are random patterns of stars that form an image in the sky?
Constellations
How many constellations are there?
88
Are stars in constellations close to each other?
No, they just appear close from earth when they are in fact thousands of light years away from each other
What represents the regions in the sky?
Constellations
What are the less formally defined group of stars?
Asterisms
Give an example of an asterism
The big dipper
What are the two types on motion that the ancient Greeks observed?
- Daily motion
2. Annual motion
What is daily motion?
Objects in the sky appear to be rising in the east and setting in the west each day (This is because the reflect the rotation of the celestial sphere)
What is annual motion?
The Sun and the Moon are slowly moving east while rotating west with the celestial sphere
What were the daily and annual motions caused by?
The earth’s rotation and the revolution around the sun
What are coordinates that anyone in the world can use to find an object?
Universal coordinates
What is the projection of the earth’s equator onto the sky called?
The celestial equator
What did we use the geocentric model to come up with?
Universal Coordinate
What is the projection of the earth’s north pole onto the sky?
The celestial north pole
What is the apparent path of the sun?
The ecliptic
What is the point directly above your head?
The zenith
What is the point in the sky directly below you feet?
The nadir
Why is the ecliptic tilted with respect to the celestial sphere?
The earth’s axis is tilted by 23.5 degrees
How many times a year does the sun rise and set directly in the east and west?
2
What are the coordinates that are only true from your location?
Local coordinates
Why are local coordinates only true from where you are?
Since the earth is sphere shaped the sky is different from different locations
Are local coordinates always go to be the same?
No, they change over time
While using local coordinates what do we use in order to figure out how far north an object is from the horizon?
Altitude
What do we use in order to figure out how far north an object is from the horizon?
Altitude
What do we use in order to figure out how far east or west an object is on the horizon?
Azimuth
In the geocentric model, what is at the center of the universe?
The earth
List the universal coordinates
- Declination
2. Right ascension
List the local coordinates
- Altitude
2. Azimuth
What measures how far north or south an object is from the celestial equator?
Declination
What is declination measured in?
Degrees
How many arcminutes does a degree have?
60
What measures how far east or west an object is on the celestial equator?
(The celestial longitude)
Right ascension
What is the celestial latitude?
Declination
What is the celestial longitude?
Right ascension
What is the right ascension measured in?
Hours, minutes, and seconds
Where does the right ascension start from?
The vernal equinox
Why are the declination and right ascension considered universal coordinates?
They are the same wherever you go, they don’t change when you change locations
In order to use the universal coordinates, what do you have to find?
Your latitude and the north celestial pole
What angle does the celestial equator make form the southern point of our horizon?
50*
How long is a solar day?
24 hours
How long is a sidereal day?
23 hours and 56 minutes
What is the time elapsed between a sun rise and the next?
Solar day
What is the time it takes for the earth to make a complete rotation?
Sidereal day
Why is the solar day 4 minutes longer then the sidereal day?
As the earth spins it also moves one degree on its orbit
Why is it warmer during the summer?
We are hit with direct sunlight and the sun stays above the horizon for a longer period of time
When is the sun farthest north from the celestial equator?
The summer solstice
When is the sun on the celestial equator, moving southward?
Autumnal equinox
When is the sun farthest south from the celestial equator?
Winter solstice
When is the sun on the celestial equator, moving northward?
Vernal equinox
What is the wobbly motion of the earth’s rotational axis?
Precession
What’s the reason for procession?
Since the earth’s equator is slightly bulged it leads to extra gravitational pull from the sun and the moon
How long does procession take to make one complete circle?
26,000 years
How many zodiac signs are there?
13
How often does the zodiac the sun enters on May 21 change?
Every 2000 years
