TELECOMMUNICATION TEST 1 STUDY
GUIDE QUESTIONS AND VERIFIED
SOLUTIONS RATED A.
There is a relation between how long it takes a planet to complete and
orbit (period) and the "size" (semi-major axis) of its orbit: P2 ~ a3
- period is easy to measure (for example, Jupiter takes 12 years to move
through all the constellations of the zodiac)
- inner planets orbit the Sun in less time than the outer planets
- period gives a way to measure the planets' average distance from the Sun
compared to Earth's average distance (1 AU)
KL #3: (Period)2 = a3
- gives relative size scale AU (in "astronomical units") of the solar system
based on easily-measured periods of the planets
- [we'll see this law allows us to measure Mass]
Kepler's Third Law relates the orbits of all of the planets together in a (fairly)
simple mathematical relationship. The planets that are closer to the Sun move
faster and complete an orbit in less time than those that are farther out.
Mercury orbits in 88 days, and Pluto takes over 200 years! This law also puts
the relative size scale on everything in the solar system. All we have to do is
measure one distance (say between Venus and Earth) and we can calculate all
the other distances to put everything on an absolute scale.
We see the same patterns, motions, and cycles in the sky that have been
seen by everyone throughout history, worldwide
• There are daily cycles, monthly cycles, and yearly cycles
• It can all be "explained" by a few simple facts...
1. The stars are so far away that the sky just looks like a sphere; their true
distances and real motion cannot be perceived (with our eyes)
, - spherical earth blocks our view of half the sky
2.how high above the horizon celestial objects appear (or whether they even
appear at all) depends on how far north or south of the equator you are
3. The Earth rotates once per day
Thus, how far east or west of the meridian they appear depends on time of
day
AZIMUTH
(0 to 360 degrees; measured east of north),
- angle measured along the horizon circle
- same as compass heading
- measured from North toward the East
- examples: North=0 degree, East=90degrees, South=180 degrees
azimuth and altitude are angles, measured in degrees.
MERIDIAN
circle (or semicircle) on sky dividing through N, zenith, and S
Zenith
point straight overhead
The declination of the ZENITH is 33 degrees viewed from Charleston
Horizon
circle where Earth and Sky appear to intersect
ALTITUDE (aka Elevation)
angle measured up from horizon (0 to 90 degrees)
azimuth and altitude are angles, measured in degrees.
Viewed from Charleston the altitude of the CELESTIAL EQUATOR is 57
degrees (at the meridian).
"Altitude-Azimuth" Coordinate System
depends on your location on Earth (different positions on Earth see same thing
but at different altitudes or azimuths and at different times)
GUIDE QUESTIONS AND VERIFIED
SOLUTIONS RATED A.
There is a relation between how long it takes a planet to complete and
orbit (period) and the "size" (semi-major axis) of its orbit: P2 ~ a3
- period is easy to measure (for example, Jupiter takes 12 years to move
through all the constellations of the zodiac)
- inner planets orbit the Sun in less time than the outer planets
- period gives a way to measure the planets' average distance from the Sun
compared to Earth's average distance (1 AU)
KL #3: (Period)2 = a3
- gives relative size scale AU (in "astronomical units") of the solar system
based on easily-measured periods of the planets
- [we'll see this law allows us to measure Mass]
Kepler's Third Law relates the orbits of all of the planets together in a (fairly)
simple mathematical relationship. The planets that are closer to the Sun move
faster and complete an orbit in less time than those that are farther out.
Mercury orbits in 88 days, and Pluto takes over 200 years! This law also puts
the relative size scale on everything in the solar system. All we have to do is
measure one distance (say between Venus and Earth) and we can calculate all
the other distances to put everything on an absolute scale.
We see the same patterns, motions, and cycles in the sky that have been
seen by everyone throughout history, worldwide
• There are daily cycles, monthly cycles, and yearly cycles
• It can all be "explained" by a few simple facts...
1. The stars are so far away that the sky just looks like a sphere; their true
distances and real motion cannot be perceived (with our eyes)
, - spherical earth blocks our view of half the sky
2.how high above the horizon celestial objects appear (or whether they even
appear at all) depends on how far north or south of the equator you are
3. The Earth rotates once per day
Thus, how far east or west of the meridian they appear depends on time of
day
AZIMUTH
(0 to 360 degrees; measured east of north),
- angle measured along the horizon circle
- same as compass heading
- measured from North toward the East
- examples: North=0 degree, East=90degrees, South=180 degrees
azimuth and altitude are angles, measured in degrees.
MERIDIAN
circle (or semicircle) on sky dividing through N, zenith, and S
Zenith
point straight overhead
The declination of the ZENITH is 33 degrees viewed from Charleston
Horizon
circle where Earth and Sky appear to intersect
ALTITUDE (aka Elevation)
angle measured up from horizon (0 to 90 degrees)
azimuth and altitude are angles, measured in degrees.
Viewed from Charleston the altitude of the CELESTIAL EQUATOR is 57
degrees (at the meridian).
"Altitude-Azimuth" Coordinate System
depends on your location on Earth (different positions on Earth see same thing
but at different altitudes or azimuths and at different times)
