The celestial coordinate of a star that is...

Question 1 of 2707066636ee928f7522a1c5192aa

The celestial coordinate of a star that is relatively constant in value is the __________.

Question 1 of 27070

The celestial coordinate of a star that is relatively constant in value is the __________.

🔍 Key Concepts

• Difference between observer-based angles (depend on your position) and Earth-based reference angles (depend only on Earth’s rotation) • How hour angles are measured on the celestial sphere (from which reference meridian?) • Which type of hour angle for a star is tied to the first point of Aries and is therefore nearly fixed for that star

💭 Think About

• Ask yourself: Which of these angles changes as you move east or west, and which is independent of your longitude? • Consider which quantity is used in star tables as a fixed coordinate, versus which is recomputed for each observer and time. • Think about whether the angle is measured from the observer’s meridian, the Greenwich meridian, or the Aries meridian, and which one makes a star’s coordinate nearly constant.

✅ Before You Answer

• Identify which options are local quantities (depend on your longitude). Eliminate those. • Identify which option is tied to the Greenwich meridian and changes steadily with time for all bodies. • Identify which option is referenced to the vernal equinox (first point of Aries) and is therefore tabulated as a nearly constant coordinate for each star.