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HAVE YOU EVER WONDERED… WHY IS THE MOON SOMETIMES VISIBLE DURING THE DAY?

By: Efraim Harari



 The moon is visible sometime during the day for most of the month, except during the new moon phase and right when there’s a full moon.

There are two main factors that help explain why we are able to see the moon during the daytime. One is the fact that the moon is highly reflective and close to the Earth, so it is very visible both in the day and night. It might help to think of the sun as a large light bulb, and the moon as a large mirror. When you look at the moon, you are seeing the light which reflects off it from the sun. The moon’s light is not nearly as intense as the sun’s, but it is up to 100,000 times as bright as the brightest nighttime star (which is why we don’t see the stars during the day, but we do see the moon).

The other factor involved is the difference in schedules of the rising and setting of the sun and the moon. Because the two do not rise and set at exactly the same times, we see the moon even during the day, when the sun is still in the sky. At full moon, though, the moon is exactly opposite the sun, causing the sun to rise at exactly the time when the moon sets, and vice versa. This gives us a very bright moon in the night sky, when the sun has set, but nothing during the day, when the sun has risen.

During the new moon phase, the moon is turned away from Earth, so we don’t see it at all, neither at night nor during the day.

Moon Facts & Stats

The moon is a large rocky ball and is the Earth’s natural satellite.

The Earth’s moon is the fifth-largest moon in the solar system.

The moon is 238,855 miles from Earth.

The moon orbits the Earth every 27.3 days.

One side of the moon is always turned away from us and is called its “dark side.” This is because the moon spins around on its axis at exactly the same speed that it orbits the Earth.

A lunar month is the time between one full moon and the next (29.53 days). This is slightly longer than the time it takes for the moon to orbit the Earth, since while the moon is doing its orbit, the Earth is also moving, around the sun. As such, the threesome – sun, Earth, and moon – are not aligned correctly, and a full moon cannot yet occur. The extra two days are needed for everything to become aligned once again, at which point there can be another full moon.

Why does the moon seem
to follow me wherever I go?

The moon seems to follow you because it’s so far away. This may sound strange; after all, how could something so far away seem to be following you?

It has to do with how your eyes and mind work together. When you are riding in a car, close things seem to move by very fast as you pass them. A tree or house near the road starts out ahead of you, but then comes up fast, and in a few moments, the object is way behind you.

Objects that are far away, however, do not seem to move very fast. If you can see a faraway mountain from a moving car, notice how long it takes for it to “pass” by. The moon is so far away that the motion of your car doesn’t change its position enough for you to notice. So, the moon just seems to follow you wherever you go.

Leaving
a Mark

Because the moon
has no atmosphere,
the footprints planted in its surface by astronauts will always remain visible.

TORAH TALK

The Lunar Cycle

Today, thanks to very precise and sophisticated technology, scientists know that the average lunar cycle is 29.53 days. But thousands of years ago, way before the satellites and atomic clocks were around, our Sages already knew that the average lunar cycle was 29.53 days.

In the Gemara (Rosh Hashanah25a), it states: Rabban Gamliel said to them, “So have I received from the house of the father of my father: The renewal of the moon is not ever less than 29 and a half days (12 hours), and 2/3 of an hour, and 73 portions of an hour.

The Rambam writes that an hour is divided into 1,080 portions. Therefore, according to the Gemara, the average lunar cycle is exactly 29.530594 days!