Lecture 6 1/23/2013 12:21:00 PM
Cycles of the Sky, Part II
Homework is due Monday.
Old homework :
The amount of time it takes like to travel from the sun = 8.3
8.3 x 60 = 498 seconds.
Light from the moon to the earth:
498 divided by 400 = 1.2 seconds.
Recap: Ecliptic and seasons:
o the apparent path of the sun along the celestial sphere during
a year (the sun appears to move eastward along the ecliptic)
o the point on the celestial sphere where the ecliptic crosses the
celestial equator from south to north, or the time of year
when the sun is at this point
o the point where the ecliptic is farthest north, or the time of
year when the sun is at this point
o the point where the ecliptic crosses the celestial equator from
north to south, or the time of year when the sun is at this
o point where the ecliptic is farthest south, or the time of year
when the sun Is at this point.
The north pole is facing the sun
The north pole is facing away from the sun
When both the north and south poles receive the same amount of
the great circle separating the night side from the day side of any
planet or satellite.
So if you are standing on the earths terminator, what time is it?
o It is either sunrise or sunset.
Reasons for seasons:
What make summer warmer than winter?
o There are two things working together:
Sun is above the horizon for longer each day
Angle of the sun: sun reached closer to the zenith
Sidereal time: Why is right ascension often given in hours:
remember: right ascension is an angle measured east from the
why is it measured in hours?
An objects right ascension tells us what time it crosses the
If one stars right ascensio