ASTR 129 Introductory Astronomy I

Recommended Activity #4

1) Viewed from Charleston, SC (latitude = 33 degrees North):

a) The altitude of the NORTH CELESTIAL POLE is 33^o.

b) The altitude of the CELESTIAL EQUATOR is 57^o (at the meridian).

c) The declination of the NORTH CELESTIAL POLE is 90^o.

d) The declination of the CELESTIAL EQUATOR is 0^o.

e) The declination of the ZENITH is 33^o.

f) The declination of the southernmost star you can see is –57^o.

2) Given the declination of the zenith from the last problem and the latitude of Charleston:

a) A star that will pass through the zenith rises at an azimuth of North of East (less than 90).

b) It crosses through the zenith (more than/less than/ exactly) 12 hours later.

c) It will set at an azimuth of North of West (more than 270).

3) On June 21, the declination of the Sun is +23.5 ^o. From Charleston, it will rise at an azimuth of about 60 ^o, pass 9.5 ^o south of the zenith, and set at an azimuth of about 300 ^o, (more than/less than/ exactly) 12 hours later.

4) On December 21, the declination of the Sun is -23.5 ^o. From Charleston, it will rise at an azimuth of about 120 ^o , pass 56.5 ^o south of the zenith, and set at an azimuth of about 240 ^o, (more than/less than/ exactly) 12 hours later.

5) On March 21 and September 21, the declination of the Sun is 0 ^o. From Charleston, it will rise at an azimuth of exactly 90 ^o, pass 33 ^o south of the zenith, and set at an azimuth of exactly 270 ^o, (more than/less than/ exactly) 12 hours later. [Note: we'll see that it doesn't actually happen quite like this; it takes more like 12 hours and 10 minutes due to atmospheric refraction].