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You can also see the Moon\u2019s shadow by making a pinhole projector, holding up a colander, or by looking at the dappled shade from a tree.<\/p>\n
As more and more of the Sun gets eclipsed, you\u2019ll notice some strange lighting effects.<\/p>\n
Normally, the edges of your shadow under the full Sun are fuzzy. That\u2019s because our big, round star generates light rays at an infinite number of angles. But as the Sun gets eclipsed into a crescent, it behaves more like a glow stick, putting out light in a more uniform direction. Objects aligned to the axis of the Sun\u2019s crescent will cast sharper shadows.<\/p>\n
You may also notice daylight starting to fade. What began as a bright, sunny day may start to appear overcast as the Moon blocks more and more sunlight.<\/p>\n
A rarer phenomenon to look for near totality is shadow bands. Shadow bands are undulating shadows that are most easily seen on plain surfaces. They are subtle, but may appear for a few minutes before and after totality, as seen in this enhanced video.<\/p>\n
Scientists are not certain what causes shadow bands, and their appearance is unpredictable. One theory is that they are created by the same turbulent air in the upper atmosphere that makes stars twinkle. As the Sun shrinks into a thin crescent \u2014 the same crescent that makes shadows sharp \u2014 the light may organize into twinkling lines.<\/p>\n
After observing the Moon\u2019s leisurely progression across the Sun, you may be tempted to forget that the Earth, Moon, and Sun are locked in a high-speed orbital dance.<\/p>\n
The Moon\u2019s average speed around the Earth is around 3,700 kilometers per hour (2,300 miles per hour), meaning the darkest part of its shadow, the umbra, travels just as fast. The Earth\u2019s rotation changes the shadow\u2019s effective speed depending on where you live, but it\u2019s still quick. If you\u2019re watching from a spot where you can see a long way in the direction of the oncoming shadow, you may be able to see it racing toward you on the ground or in the clouds.<\/p>\n
As the last of the Sun\u2019s rays disappear, you may see what looks like a string of beads along the Moon\u2019s limb. These beads are caused by sunlight slipping through lunar valleys \u2014 you\u2019re actually seeing the Moon\u2019s topography!<\/p>\n<\/div>\n