In the daytime sky a tiny crescent Venus is visible near a much larger crescent Moon. Since Venus is between the Earth and the Sun it can only be seen from the Earth in a crescent phase, first noticed by Galileo in 1610 (the actual original telescope Galileo used for this purpose is on page 260 in You and the Universe). Astrophotographer Iván Éder caught "something behind those clouds. Those faint graceful arcs are the Earth’s Moon and the tiny planet Venus to its left. Both are bright enough to be seen during the day. To see Venus—which appears quite small—in a crescent phase requires binoculars or a telescope. In the above dramatic daytime image the Moon and Venus shared a similar crescent phase a few minutes before the Moon eclipsed the larger but more distant world. About an hour later, Venus reappeared" on the other side of the moon.

Now the Moon is ½° or 30' wide and moves at about ½°/hour, so it moves across the sky (daytime or nighttime) an amount equal to its diameter every hour. Also the Moon is ¼ million miles from Earth and Venus varies between 24 and 162 million miles from Earth. In this photograph Venus is about 50 million miles from the Earth and appears to be 1' (or 1/60°) wide. The Moon is actually much smaller than Venus, but because it is over 200 time closer it appears much larger. Venus is just about to be eclipsed by the Moon which is moving to its left. Then it takes another hour for the Moon to move out of the way so that Venus is visible again. A larger and more highly resolved image of this eclipse is on page 123 in You and the Universe.