Question about the moon during daytime?

Question

My daughter (who's 9) keeps asking me if, when its daylight an we can see the moon in the sky, what is happening on the other side of the world where it is night? It has me stumped.

Answer 1

Why do we see the Moon in the day? Of course, it's there but many things are there that we don't see. We don't see the bright star Sirius in the day. We do see the Moon. Often it's like a beacon in the blue sky we follow through summer woods.The Full Moon has about 1/400,000th the brightness of the Sun. Yet the Full Moon sheds enough light that we can read a newspaper at night. It's over 33,000 times brighter than Sirius, which helps explain why, in the daytime, we don't see Sirius but do see the Moon.

I read that the Moon has one of the lowest reflectivities of all the objects in the Solar System. Curious. It looks bright and white even with an average reflectivity of an asphalt parking lot.

Almost every day in a lunar month, we can see the daytime Moon. The days we cannot are when the Moon is Full, when it's New, and a few days before and after the New Moon.

An exactly Full Moon is invisible (or at least not easily seen) during the day because then the Moon is opposite the Sun with the Earth in between. The Full Moon sets when the Sun rises (except near the poles) so we can't see the Moon during the day. It's below the horizon, shining brilliantly on the other side--the night side--of Earth.

When the Moon is New it will be dark and unseen and, for at least two days either side of the New Moon, the Crescent Moon will be "too faint and close to the Sun to be seen with the naked eye--although it might be glimpsed at sunset," says Robert Massey, astronomer at the Royal Observatory Greenwich.

The Moon is close to Earth and that's why we see bright sunlight reflected from its asphalt-parking-lot surface even in the daytime and even when part of the Moon is in shadow. Step outside on or about the 14th of June, and find the daytime Moon. It's there--a shiny half moon, high and West.  

Answer 2

They on the other side are experiencing a new moon day.

Answer 3

You know those nights when you can't see the moon?  That's because it's not on the "night" side of the earth at that specific time.  It's actually in the sky quite frequently during the daytime, however, if it's close enough to the sun, it's not visible during the day, due to the amount of it that is lit is not significant enough to produce enough brightness to overcome the brightness of the sun and the sky.

I'm clearly not very good at explaining this, and explaining it to a 9 year old is something I don't even want to attempt.  But I hope I was at least a little bit helpful and you can find the answer that will help her understand, and still not be overwhelmed with information.

Answer 4

It's one of those moonless nights when the stars are bright and beautiful.

Answer 5

Hi Mad!

Since the earth is a globe, there will always be a half facing the direction of the moon, and the other half of the planet facing away from the moon.  When we're on the side facing away from the moon, we have to wait for the earth to turn far enough for us to get back to where we're facing the moon again.

The same happens with the sun.  At any moment, half the world is on the side facing the sun, and it's day; and the other half is on the night side facing away.

The moon is moving around the earth in an orbit of its own, taking about a month to complete it.  (Actually, it takes the moon 29 1/2 days to make a complete circle and catch up with the sun again.)  This means that there will be times when the moon is in the same area of the sky as the sun, and we can see both at the same time.  

About two weeks later, the moon will have moved to the other side of the earth from the sun, so we see the moon without the sun -- in other words, at night.  At those times, people on the side of the earth where you can see the sun -- the  daylight side -- cannot see the moon.  Those on the night side of the earth, at those times, cannot see the sun (by definition) but they can see the moon.