The Moon in the Daytime

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


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)