We are fortunate to have the Moon as such a close celestial friend in the sky. During a full moon, it beautifully illuminates our nights to guide us. We have a habit of associating the Moon only with nighttime, but how is it that we can sometimes see the Moon during the day?
The Moon is Luminous
The Moon is by far the closest natural object to us in the entire Solar System. With the exception of a rare passing meteor, it’s the only object within millions of miles.
It doesn’t hurt that the Moon is one of the largest satellites in the Solar System. It ranks fifth in size after three of Jupiter’s and Saturn’s largest.
It makes sense that, due to its proximity, the Moon is so luminous to us in the sky. If you’re not already aware, every beam of light from the Moon does not originate there. On the contrary, it is the Sun’s rays that give the Moon its glow.
The Moon actually does not have a very reflective surface at all. Nearly 90% of the light that reaches its surface is absorbed by the Moon’s dark, volcanic rock. Even so, the Sun sends enough light to the Moon that we can often see it very clearly.
The Moon indefinitely holds the title of the brightest object in the nighttime sky. The Moon’s brightness changes very little depending on whether it’s day or night. This luminosity is the very reason we’re able to see the Moon at times during the day.
The Moon’s Location in the Sky
The other factor that plays a part in the Moon’s visibility during the day is its location in the sky.
Due to a cosmic optical illusion, it looks like the Sun and Moon are chasing each other across the sky. At times, the Moon appears to be very close to the Sun, and at others very far away.
The Moon is at its smallest as it draws closest to the Sun, visible as only a crescent in the sky. Once per month, these two celestial objects are on top of each other as seen from the Earth. When this happens, the Moon disappears and cannot be seen.
The opposite phenomenon also holds true. As the Moon moves away from the Sun in its orbit around the Earth, it exposes more of its Earth-facing side to the Sun’s rays. The result is a brighter Moon in the sky.
The Moon’s distance from the Earth’s horizon also plays a significant role in how we view the Moon. As the Moon climbs in the sky, its reflected light shines more directly down to the Earth. At this elevated location, those same rays have less of the Earth’s atmosphere to travel through.
Even on a clear day with a clear view of the horizon, it’s quite difficult to see the Moon at moonrise without the aid of binoculars or a telescope.
What Phases of the Moon Can Be Seen During the Day?
No matter how luminous the Moon may be, there are certain times of the month where it’s just not possible to see the Moon during the day.
For instance, a new moon is entirely invisible to us on Earth because the Sun’s rays shine only on the side of the Moon we never see from Earth. When it comes to a full moon, it rises as the Sun sets. The full moon is only out during the night and won’t be seen during the day.
For all the other phases of the Moon, they can be seen at some time during the day. All that’s required are clear skies.
If you’re hunting for the Moon in the morning, there are a few lunar phases that you can be on the lookout for.
A waxing crescent moon rises just after the Sun in the morning and follows the Sun across the sky. It will be visible from mid to late morning and travel across the sky throughout the day. If too close to a new moon, a waxing crescent moon may be difficult to see.
A third quarter moon rises at midnight but is at its highest point in the sky as the Sun rises in the morning.
A waning gibbous moon will be preparing to set in the western sky as the Sun comes up in the morning. Early birds should be able to catch a glimpse of the waning gibbous moon before it sets.
A waning crescent moon rises just before the Sun in the morning, and the Sun will chase it across the sky throughout the day. As with the waxing crescent moon, it will be hard to spot once it gets too close to the Sun’s bright light.
Those looking for the Moon in the afternoon have a few options as well.
A waxing crescent moon will be visible in the afternoon sky as it chases the Sun.
A first quarter moon makes an appearance at noontime and will show itself off to onlookers as it climbs higher in the sky in the afternoon.
A waning crescent moon will be just in front of the Sun in the afternoon sky to those searching for it.
A waxing crescent moon will set just after the Sun, so it will still be visible even into the evening hours.
A first quarter moon will be at its zenith as evening sets in, offering what light it can as the Sun sets.
A waxing gibbous moon will make its appearance in the early evening hours but will stay near the eastern horizon until after dark.
The Moon will likely forever be the brightest object in the nighttime sky but will forever hold a second candle to the Sun during the day. The Moon owes all the luminosity it has to the Sun in the first place, so second place isn’t all that bad. As long as we follow the Moon’s current phase, we get the benefit of seeing our closest neighbor at whatever time of day we want.