How Can Your Thumb Hide the Moon?

How can your thumb hide the Moon, when the Moon is about 2,160 miles (3,476 km) wide? Your eye doesn't judge how big something is, but how many of its own widths away it is. A 1-inch (2.54 cm) thumb held 25 inches (63.5 cm) from your eye is 25 thumb widths away, while the Moon, about 238,855 miles (384,400 km) away on average, is about 111 Moon widths away. So your thumb looks over 4 times as wide as the Moon. You'll see the same rule with a coin and a dinner plate: a 1-inch coin held 10 inches away and a 10-inch plate 100 inches away are both 10 of their own widths away, so the coin just covers the plate. The video also turns widths into an angle (the Moon spans about half a degree of sky), shows why the Sun, about 108 of its own widths away, looks almost the same size as the Moon, and explains why the Moon's changing distance gives both total and annular solar eclipses. Try it yourself: ▶ https://www.metric-conversions.org/angle/radians-to-degrees.htm Chapters: 0:00 The puzzle 0:23 Counting widths 1:45 Your thumb and the Moon 2:19 Turning it into an angle 2:45 The Sun 3:06 Two kinds of eclipse 3:46 Takeaway Sources: • Moon Fact Sheet (NASA NSSDCA): https://nssdc.gsfc.nasa.gov/planetary/factsheet/moonfact.html • Sun Fact Sheet (NASA NSSDCA): https://nssdc.gsfc.nasa.gov/planetary/factsheet/sunfact.html • Types of Solar Eclipses (NASA): https://science.nasa.gov/eclipses/types/ • Visual angle (Wikipedia): https://en.wikipedia.org/wiki/Visual_angle • Radians to Degrees (metric-conversions.org): https://www.metric-conversions.org/angle/radians-to-degrees.htm Is there anything else you'd like us to cover? Let us know in the comments below.