I was visiting the Tall Ships event in Dublin recently when I noticed something strange in the light blue daytime sky!  Overlooking the River Liffey I could see something that looked like the Moon, but the Sun was still shining, so it couldn’t have been the Moon – or was it?

Image of Tall ships

"All I ask is a tall ship and a star to steer her by" (Image credit:Sinead McNicholl)

The Moon orbits the Earth, is the only natural satellite of our planet and is the brightest object in the sky after the Sun.  The Moon does not give out any light of its own, it actually reflects the Sun’s light and that it why we can see it.  The gravitational influence of the Moon also produces our ocean tides so our satellite  is very important  for life on our planet.  The Moon is the only celestial body, apart from the Earth, on which humans have set foot.  The United States’ NASA Apollo program achieved the only manned missions to date.  The program began with the first manned lunar orbiting mission by Apollo 8 in 1968, and six manned lunar landings followed between 1969 and 1972.  The first lunar landing was Apollo 11 which landed in July 1969 with Neil Armstrong and Buzz Aldrin onboard.

Image of Aldrina

All alone.Buzz Aldrin on the Moon (Image credit:Neil Armstrong/NASA)

 

The common belief is the Sun during the day and the Moon only at night.  However as I have discovered with my own eyes this is a misconception.  This mistaken belief stems from the line of thought that the Moon is directly opposite the Sun in the sky.  This is actually only true when there is a full Moon (once a month).

 

image of Moon

Our satellite, the Moon (Image credit:via wikimedia.org)

 

Basically it takes the Moon 29.5 days to complete its orbit around the Earth so it passes the Sun in the sky once every 29.5 days (called a New Moon) and then moves slowly away from the Sun until it is exactly opposite the Sun (called a Full Moon) two weeks later. At any point in these two weeks, you can see the Sun and the Moon in the afternoon sky at the same time. At Full Moon, the Moon rises in the east at exactly the same time as the Sun sets in the west, and that is the only night in the month when the Moon is in the night sky all night long. After a Full Moon, our satellite continues on its orbital journey, moving towards the Sun on the opposite side, and again Sun and Moon can be seen at the same time, but in this instance in the morning sky. After another two weeks, the Moon approaches the Sun and is lost in the Sun’s brilliance for a few days. Basically, having both the Sun and the Moon in the sky simultaneously is quite a normal thing.

 

 

So, we have seen that the Moon doesn’t follow the exact same path of the Sun.  This contributes to why we might see it in the daytime, but are there any other factors which make the Moon more visible in the day?

Yes!  Firstly the Moon is very close to the Earth, it is a satellite of the Earth which means that it orbits around us.  The Moon is 238 855 miles or 384 400 kilometers away from us.  Secondly, it is also very reflective.  The surface of the Moon is coloured grey (it’s basalt like the rocks at the Giants Causeway), so it reflects the Sun’s light quite easily.

 

image of the Moon in Daytime

Daytime Moon.To quote a teacher who once phoned the Planetarium "What is that big white planet you can see in the daytime?" (Image credit:Sinead McNicholl)

 

To sum up, what do you need to see the Moon in the daytime? Here are some top tips:

  •        Look within a week or so of the date of full Moon.
  •        Before full Moon, look for the daytime Moon in the afternoon.
  •       After full Moon, look for the daytime Moon in the morning.
  •        Look up!The daytime Moon is often up there, but it’s pale against the blue sky.

At time of writing (28 August 2012) the Moon is at a waxing gibbous, so perfect to catch a glimpse of during the daytime.  I personally believe that not that many people know about the daytime Moon because they don’t look up at the sky that often!  If you begin to look at the sky, you’ll begin to notice the daytime moon.  Once you see it you will fall in love with it.  It is very beautiful and quite serene, hovering against the blue sky.  And if the sky is a dark blue it shines like a beacon!

So get out a view the daytime Moon, you won’t be disappointed with what you see!

(Article by Sinead McNicholl, Education Support Officer)


15 Comments

Anna · July 31, 2019 at 04:46

In all pictures of the moon, the sky appears dark. I thought astronauts landed during the moon’s morning time. Would the sky appear dark (like Earth’s nighttime sky) to them or is it just reflected that way in photos? Is it truly always a dark sky because there’s little (or no?) atmosphere?

    Armagh Observatory and Planetarium · July 31, 2019 at 09:18

    Hi Anna, the sky is perpetually “dark” if you are standing on the moon as its very thin atmosphere acts almost as a vacuum which does not allow for light to be scattered amongst the molecules contained within it, like it does on earth. The sky during the day on the moon is dark except for our bright, beaming star at the centre of our solar system (the sun) proudly visible from its surface. 🙂

Unkown · May 13, 2016 at 16:14

Wake up, the earth is not a ball? It’s flat, look at videos of normal non fish eyes lens, no curvature on the earth in 360 degree angles from 200,000 ft. Also while I understand you see noon in daylight during day, tell me why in videos you can see night moon (not daylight moon in picture at top) and the sun both above ‘so called horizon’ of our globe! And also a full moon, we are told in the order left to right, moon – earth inbetween – sun. The earth is far larger than the moon so when we have the sun from the right across to the earth with the moon to the left, how is the full moon light when the earth is nearly four times bigger than the moon. Wake up people nasa are liars and man has never been to the moon, also nasa admits in loads of videos and astronauts been interviewed in space about van Allen radiation built and that no man has been beyond the earths orbit yet. And the new Orion project maybe the first to do so. Wakey wakey people, do some research on ‘flat earth’ plenty of different reasons and suggestions that suggest we are not on a ball.

    admin · May 16, 2016 at 09:29

    Dear Unknown, thank you for your comments and questions. I’ll try to help.

    look at videos of normal non fish eyes lens, no curvature on the earth in 360 degree angles from 200,000 ft.

    Why do you think this is proof that the Earth is flat? If the Earth is a sphere (more or less) about 13800 km in diameter, should its curvature be visible from just 61km (200 000ft away)? Here is an experiment you could do to illustrate why I think this argument is invalid: blow up a 24 inch (60 cm) beachball. Look down on the ball, holding your eye 0.1 inch (0.27 cm) from it. This is exactly in proportion with the Earth from 200 000ft. Can you see the curve of the ball?

    tell me why in videos you can see night moon (not daylight moon in picture at top) and the sun both above ‘so called horizon’ of our globe!

    I do not understand your question; what do you mean by “night moon” and is it different from “daylight moon”?

    And also a full moon, we are told in the order left to right, moon – earth inbetween – sun. The earth is far larger than the moon so when we have the sun from the right across to the earth with the moon to the left, how is the full moon light when the earth is nearly four times bigger than the moon.

    If I understand you, you are asking why the Earth doesn’t block the Sun’s light from falling on the Moon. Well, it does several times a year during lunar eclipses. We don’t get a lunar eclipse every month because the Moon’s orbit is large compared to the Earth (about 380 000 km radius) and is inclined at about 5 degrees from the plane of the Earth’s orbit around the Sun (the ecliptic). This means that the Sun, Earth and Moon are only aligned well enough for the Earth’s shadow to fall on the Sun a few times a year.

    …man has never been to the moon, also nasa admits in loads of videos and astronauts been interviewed in space about van Allen radiation built and that no man has been beyond the earths orbit yet

    I will not believe this unless you provide a sourced quote from a NASA employee stating that humans have not been to the Moon.

    do some research on ‘flat earth’

    I agree that you should do this, but remember watching online videos without asking yourself “is this true?” is only a tiny part of the research process. You need to look a bit wider and work a bit harder (which is all part of the fun). Have you considered joining an astronomy club or taking an astronomy course? Just to give you an idea of the wider world you could join, astronomers at all levels from amateurs in their gardens to professionals use equatorial mounts to aim their telescopes and accurately track the movements of astronomical bodies. The thing is that an equatorial mount depends on the Earth being a rotating globe. It would not work on a flat Earth.

    I hope this has helped you.

Janet · February 13, 2016 at 20:57

Nai. Yes, that puzzles me also. Why does the shaded area of the moon during the day appear the same blue as the sky? I live in New Zealand and have been watching the crescent moon during the day and the shaded area is definitely the same shade of blue as the sky through my eyes.

    William Diffin · January 20, 2019 at 12:17

    Because the blue of the sky is brighter than the reflected Earthlight on the shaded area of the crescent Moon which you would normally see it by at night.

Nai · December 9, 2015 at 06:30

Why is the moon blue in the day time?

    admin · December 10, 2015 at 09:41

    Dear Nai, I’ve never heard this before. It doesn’t look blue to me!

    Dr.SHWETA MG BDs · May 10, 2016 at 16:33

    The moon is a heavenly body that emits light from the sun as it has also been mentioned above, and the ability to see colors is because the color of the sea is blue due to tons of algae at the floor of the ocean…..follow me on this logic rather explanation……

    So in essence this massive algae carpet at the floor of the ocean produces it’s by product of blue pigment that is their blue chlorophyll . Like plants on land the algae undergo photosynthesis.
    The blue is blue because it absorbs all colors of the visible light spectrum except the color blue. Funny concepts of nature but this blue light is reflected in the sky which is otherwise colorless ……
    We call the skies blue because of this phenomenon and when clouds are passing , as the author has explained so well, the new moon on its 28.5 th day passing a complete orbit around earth is

    Seen at the same time as the sun or in the sky with many layers of thin atmospheric gases diffusing visible light and a series of reflections and refractions of the moon

    This is why in a sorry very long winded explanation

    The MOON IS BLUE IN THE DAY SKIES.

      admin · May 10, 2016 at 21:24

      Dear Dr Shweta, thank you for your comments, but I am not convinced that you are correct. I have never heard the claim that sea water is blue because blue light is reflected from algae before and I have doubts that this has a major role in determining the sea’s colour. I believe that it is more a a consequence of water absorbing the longer wavelengths of light.

      Funny concepts of nature but this blue light is reflected in the sky which is otherwise colorless ……

      I am afraid this is not correct. We have known for centuries that the air molecules in the atmosphere scatter blue light from the Sun more than they scatter red light.

Hugh · January 19, 2015 at 14:45

(Content removed- Dear Hugh, if you do not like what you see here please read something else instead. Do not waste everyone’s time trying to post insults to us and other commenters- ADMIN)

Chris freshwater · December 10, 2014 at 08:45

why is the moon only a partial moon when the sun is out ,would of thought it would be full ,as the sun reflects of it to give it light . I guess it must be still partially shaded by earth ? .

    admin · December 10, 2014 at 11:29

    Dear Chris, that’s a good question, have a look the article How Can You See the Sun and the Moon at the Same Time? at the Universe Today site. The diagram there is especially helpful.

    The Moon is only shaded by Earth during lunar eclipses which happen a few times a year (the Moon’s orbit is slightly inclined to the plane containing the Earth and Sun, if the Moon’s orbit was on the same plane and the Earth and Sun, we would have a lunar eclipse every month!)

    William Diffin · January 20, 2019 at 12:25

    It is actually possible to see the Full Moon when the Sun is out, but only when the Sun is at the horizon, with the Full Moon at the opposite horizon, at either Sunrise or Sunset. The Moon can even be in total eclipse at the same time. Also it helps if you’re standing on a tall hill 🙂

10 "Facts" About Space That Aren't True | Astronotes · March 5, 2015 at 11:33

[…] the moon in the daytime sky in the afternoon, after a full moon it will be visible in the morning. (https://www.armaghplanet.com/blog/the-moon-in-the-daytime.html) […]

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