Saturday, January 14, 2012

On a clear night, how may constellations of the zodiac can be seen at once?

If not for the sun, could a person see all 12 (or 13) constellations of the zodiac rise and fall in 24 hours, regardless of the time of year? Are we only able to see a portion of the zodiac constellations at a given time because the sun is in one of them, blocking them from view due to day time?On a clear night, how may constellations of the zodiac can be seen at once?
At any given time in the night sky, you can only see a hemisphere, so that's 1/2 of the zodiac at any given time.On a clear night, how may constellations of the zodiac can be seen at once?
At any given time, only 6 of the zodiacal constellations (or 7 if you include Ophiuchus) can be above the horizon. However, if you look at a time when the Sun is close to the border of two constellations, at least a part of those two should be visible, one just before sunrise and the other after sunset. The remainder should be fully visible during a complete night.On a clear night, how may constellations of the zodiac can be seen at once?
Realistically, about 4 or 5. Right now in my sky (which is cloud covered for the fourth day in a row), part of Leo, Virgo. Libra, Ophiucus, Scorpius, Sagittarius, Capricorn, and most of Aquarius are above my horizon. That's seven, eight with Ophiucus, constellations total. The sun is in Virgo. The stars in Capricorn and Aquarius are not bright, and then there atmospheric effects within about 10 degrees of the horizon. Yes, you are correct, the only reasons that you cannot see all 12 or 13 constellations of the zodiac in 24 hours (23 hours 56 minutes 43 seconds, because Earth moving in its orbit around the sun)is because of the sun and scattering of sunlight by air molecules (Rayleigh scattering), clouds (Mei scattering), pollution (natural or anthropogenic), and air turbulence

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