AST 3018
HOMEWORK ASSIGNMENT #1
KEY
1.
If I am located at 10° south latitude and observe an object at 3° south declination:
a. Where will it rise? (North of East, Due East, South of East) – South of East
b. How far from and which direction from the zenith will it transit? - 7 degrees
North
c. Where will it set? (North of West, Due West, South of West) - South of West
2.
I am located at 40° north latitude. I see a star transit 15° south of my zenith. What is its
declination? – 25 Degrees North
3. I am in Santiago, Chile (30° south latitude). What stars are circumpolar? – All stars
whose declination is greater than or equal to 60 Degrees South latitude
4. The Sun is setting on September 21.
a. What are it zenith angle and azimuth? – Zenith Angle = 90 Degrees, Azimuth =
270 Degrees
b. What are its hour angle, right ascension and declination? – Hour Angle = 90
Degrees, Right Ascension = 12 hours, Declination = 0 Degrees
5. If the declination of the Sun is 10° north and I observe it to transit 22° south of my zenith,
what is my latitude? – 32 Degrees North
6. Consider two points on the Earth’s surface that are separated by 1 arcsecond as seen from
the center of the Earth. What is the physical distance between the two points? – 29.1
meters if you use R=6000 KM, 30.9 meters if you use R=6378 KM (the Earth’s radius at
the equator.)
7. Consider two points on the Earth’s equator that are separated by 1 second of time. What
is the physical distance between the two points? 463 meters
8. Ancient Polynesian inhabitants of the Pacific held festivals whenever the Sun was at the
zenith at local noon.
a. How many times per year was such a festival held? 2
b. At what time(s) of the year was the festival held on:
(1) Tahiti (Lat. = 17°56’ S) Mid-November (Nov. 13) and Late
January (Jan. 30)
(2) Oahu (Lat. = 21°19’ N) Late May (May 28) and Mid-July (July 17)
Look up their latitudes.