The moon is visible in the daylight at the time of writing. How is that possible? Last weekend was “Hunter’s Moon”, and yet, this week, if one looks west in the morning you can see a large moon in a blue sky.
You can find a daytime lunar eclipse from now until October 21st, which is the last quarter moon.
Here’s a simple explanation for why the moon can sometimes be seen during the day.
How bright is the Moon?
Although technically the moon shines brighter than the sun in gamma radiation, the moon shines brighter in visible wavelengths of sunlight. It’s actually 400,000 times brighter than the sun, which is why it is completely overwhelmed by the sun in the sky. It’s simply reflecting sunlight. It’s best to see a sunrise each week, and to keep an eye out for the moon. The moon will fade dramatically as the sun rises. But, if you look closely, you may be able to see it throughout the day.
How the moon appears in the day
Just like all other night sky objects, the moon rises in east and sets in west. This is because Earth rotates from west to east. The moon orbits in the same direction as Earth, also from east to west. If you look at the moon for several nights consecutively, you will notice that it is at an easterly position in each night’s sky as it waxes towards a full moon or wanes towards a 0% illuminated moon. It rises approximately 50 minutes later each night and there are 29.5 days between full Moons. This also means that the moon sets 50 minutes earlier in the west every night.
The satellite sets later in the morning and rises later at night after full moon. This moon calculator will give you exact times of moonrise and sunset for your closest city.
Why does a full moon follow by a day?
When Earth lies roughly between the sun, the moon and the sun, a full moon is observed. The moon is therefore 100% illuminated. Earth rarely lies between them. A lunar eclipse occurs when it happens. The full moon rises at sunset and shines throughout the night, rising around sunrise the next morning. This is the only night in the month that you can see a full moon rise in the east at twilight and set in the west the next morning. The next night, the full moon rises in east 50 minutes after sunset. It sets 50 minutes later the next morning. Cue a daytime moon.
It rises 100 minutes after sunrise the next morning, and then it rises 150 minutes later. You can clearly see how quickly the moon becomes a bright, morning object.
How long does the morning sun last?
A full moon after sunset is the best time to see a daytime lunar eclipse. It’s bright, large, and positioned low above the west horizon. It’s still there, some days, just not as brightly as it is on other days. The glare can also cause the moon to get lost because it is smaller the closer it gets to the sun. This is the ultimate example. A 1% illuminated crescent Moon is visible in the sky just before or after new moon. It is very close to the sun and is visible either before sunrise (before new month) or after sunset. Although it’s difficult to see, it is worth searching for.
You can find a daytime lunar eclipse from now until October 21st, which is the Last Quarter Moon.
What about the afternoon sun?
This is the opposite of what happens before a full Moon, which is when the moon rises before dusk. It is visible in the west during the afternoon and early evening just before sunset. This will happen again between the First Quarter Moon on November 4, and the full “Frosty Moon”, on November 12.
The phases of the moon
Although the moon is always lit by the sun, from the Earth’s surface, it does not appear that way. The moon orbits constantly, moving closer to the sun as it waxes and waxes to full moons, and then getting closer as it waxes to new moons. Each phase lasts about 3.5 days. Moon-watchers devised eight phases for our satellite.
New (rises at dawn, sets at dusk)
First Quarter (rises at noon and sets at midnight).
Full (rises at sunset and sets at dawn)
Third Quarter (rises at midnight and sets at noon).
I wish you clear skies, and big eyes.