How would you determine what phase of the Moon would be in ten days?

Answer 1

-- Take a large sheet of paper. Draw a line of 29 boxes on it. In these boxes, you'll draw the shape
of the moon in each day of its cycle of phases.

-- In Box-#1, print the words "New Moon". That's the day when you can't see the moon at all.

-- In Box-#2, draw a very very skinny crescent, not much more than a thick pencil line. The curve
of the crescent is on the right, and the points at the ends point to the left.

-- In Box-#8, draw half of a moon. The right half is there and the left half is not there.

-- In Box-#15, draw a full moon.

-- In Box-#22, draw half of a moon. The left half is there and the right half is not there.

-- In Box-#28, draw a very very skinny crescent, not much more than a thick pencil line. The curve
of the crescent is on the left, and the points at the ends point to the right.

-- Now, in all the boxes that are still empty, draw a series of drawings that change gradually and
smoothly from the last box that has something in it to the next box that has something in it.

-- When each box has a drawing in it, bend the line of boxes into a big circle, and connect Box-#1 to Box-#29.
If you can't actually form them into a big loop, just remember that as the moon goes around the cycle, after
it reaches #29, it goes directly to #1 again.

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Now you have your own moon-phase calculator.

Whenever you see the moon in the sky, find the shape on your calculator that most resembles it.
From that box, you can count days. Each box is one day. If you want to see what the moon's phase
will be in ten days, count ten boxes forward from where you are now, and the phase for that day is the
drawing in the tenth box forward.