Question

State true or false:

At dawn or dusk, the sun appears to be above the horizon for three or four minutes longer than it really is.

• A. True
• B. False

Answer 1

Answer: (B)

At the equator, the Sun rises perpendicularly from the horizon and sets perpendicularly, also the total path of the Sun is divided equally by the horizon. since we mark the instant of sunrise as the time the Sun's upper edge, the actual center of the Sun is still below the horizon by half the diameter of the Sun, 16 arc and it will take an additional minute for the Sun's center to be on the horizon. Same thing happens at the sunset so an additional two minutes are gained for daytime. Also, when the Sun's limb appears on the horizon, it is actually 43 arc minutes below the horizon but appears to be on the horizon due to the refraction by the Earth's atmosphere. This effect causes the sunrise to appear about three minutes early and sunset late by the same amount.