Astronomy Practice Exam

How many times does the sun appear to circle the celestial sphere in a year?

1. Once

2. Twice

3. Four times

4. Every 24 hours

The correct answer is: Once

The sun appears to circle the celestial sphere once a year due to the Earth's orbit around it. From our perspective on Earth, as we move along our orbital path, the sun seems to move against the background of stars, completing one full circuit through the zodiac over the course of the year. This phenomenon is a result of the Earth's revolution around the sun, which takes approximately 365.25 days to complete. Each day, while the sun rises and sets in roughly 24-hour cycles, we perceive its annual movement as one complete traversal through the sky from our vantage point. This axis and orbit create the illusion of the sun journeying through different constellations over the year, but fundamentally, it is just completing one full journey around the celestial sphere in that annual cycle. The other options might suggest multiple traversals or daily cycles, but they do not accurately reflect the sun's annual path in the celestial sphere context.