ASTR 101 Problem Set 01

Instructions

Show reasoning, units, diagrams or plots where useful, and source acknowledgments. Numerical answers without explanation receive limited credit. Eligible submissions may be revised after feedback.

Concrete Problems

1. Angular Speed of the Sky 12 points

A student begins observing a bright star when it is 35 degrees above the eastern horizon. Assume the star's apparent motion is dominated by Earth's rotation at about 15 degrees per hour. Estimate the star's altitude change after 90 minutes if its path is approximately vertical near that horizon location. State why this is only an approximation.

2. Coordinate Systems for an Observing Plan 14 points

You are given a target at RA 5h 30m, Dec +20 degrees. Explain which parts of that coordinate are reusable by observers anywhere on Earth and which observing quantities still depend on local time and location. Include one sentence about why altitude-azimuth coordinates are still useful at the telescope.

3. Moon Phase Geometry 16 points

Draw or describe Sun-Earth-Moon geometry for first quarter Moon. Identify the approximate angle Sun-Earth-Moon, when first quarter is highest in the sky, and why this phase is not a lunar eclipse.

4. Observing Log Critique 8 points

An observing note says: 'Saw Jupiter near the trees. Looked bright.' Rewrite it as a scientifically useful note with at least six pieces of information that would make the observation reproducible.

Recommended OpenStax Practice

OpenStax Astronomy 2e, Observing the Sky exercises, Review Question 1, extracted index line 5155: latitude/longitude compared with declination/right ascension.
OpenStax Astronomy 2e, Observing the Sky exercises, Review Question 3, extracted index line 5158: Moon phases, rise/set timing, and phase visibility.
OpenStax Astronomy 2e, Observing the Sky exercises, Thought Question 24, extracted index line 5199: seasons and the misconception that distance causes seasons.
OpenStax Astronomy 2e, Observing the Sky exercises, Thought Question 25, extracted index line 5203: sky appearance from different places on Earth.

Recommendations are keyed to the extracted local textbook reference at references/openstax-astronomy-2e-extracted.txt; consult the adopted edition before assignment.