1. A sidereal day is approximately four minutes _____________ than a solar day.
2. The period of the precession of Earth’s axis is about ___________ years.
3. ___________ is the point directly over the observer’s head.
4. In the horizon system, an object’s coordinates are given in _____________ for the vertical coordinate and ______________ for the horizontal coordinate.
5. In the equatorial coordinate system, objects in the sky are imagined to be positioned on the inside surface of a huge celestial _____________.
6. A great circle through the celestial poles and an observed object is called the object’s _________ _____________.
7. The ______________ ________________ is the point on the celestial sphere where the sun crosses the intersection of the celestial equator and the plane of Earth’s orbit around the sun (the ecliptic).
8. In the equatorial system, an object’s coordinates are given in ____________ for the north-south coordinate, and ____________ _______________ for the east west coordinate.
9. In an hour angle-declination (HA-DEC) radio telescope antenna, the HA axis is parallel to ___________ ____________ _________.
10. Because Earth rotates on its axis once in 24 hours, a HA-DEC telescope can track a star by rotating in the ______________ direction every 24 hours.
1. shorter 2. 26,000 3. Zenith 4. elevation, azimuth 5. sphere 6. hour circle 7. vernal equinox 8. declination, right ascension 9. Earth’s rotation axis 10. opposite
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