This is a sunrise over the Gulf of Mexico, from a beach near Destin, Florida (05:46 CST 22 Nov 2010). The white dot up in the clouds is Venus, barely more than a pixel, about 40% from the left, 80% up. Venus, when it is visible, is always very bright, fifteen times brighter than the brightest star. That morning I watched it disappear behind the clouds, but the clouds burnt off later in the morning. The sun was fully visible when I mentioned over breakfast that Venus was still in the sky and I looked up and found it almost immediately. I'd never done that before, although I'd found Venus in the day sky many times, usually by first using binoculars and calculating its position in the sky. Sometimes I've showed it to groups of elementary school kids--who could usually see it much easier than I can. Views of Venus may have contributed to the myth that stars can be visible during the daytime.
To me, one of the most remarkable coincidences in astronomy is the consistency of the brightness of Venus. Brightness of a planet varies as the inverse square of the distance, and our distance to Venus varies more than any other planet, because Venus gets so close to Earth. However, when it is close, we see its dark backside, and very little of its sunlit side. The two opposing effects neatly cancel each other, and the net result is that our perception of Venus is that it changes very little in brightness. It is always close to the sun in our view, because it is closer to the sun than the earth, but whether it is on the other side of the sun, or on this side of the sun, there is very little difference in its brightness, the total range is less than one magnitude. Mars varies by over four magnitudes, Mercury over eight, and even far away Jupiter and Saturn vary by over a magnitude.
