Why can we see a white Moon during the day?

The Moon takes about a month to circle Earth once. Over that time, moonrise gets later by about 50 minutes a day. So on some days the Moon rises in the middle of the day, and on others it is still in the sky, not yet set, after the Sun comes up.

NASA also explains that the Moon spends almost as much time in the daytime sky as at night. Picture books and weather forecasts have long drawn the Sun for day and the Moon for night, which is the only reason a daytime Moon feels strange.

The Moon doesn't make its own light; it looks bright because it reflects sunlight. In the daytime, sunlight scatters through the air and the whole sky glows blue. Set against that bright background, the Moon isn't as sharp as at night and looks white and faint.

The stars are still in the daytime sky too, but they are too dim and get lost. The Moon is far brighter than any star, so it shows up even in a bright sky. A daytime Moon looks slightly bluish because the blue skylight between us and the Moon is added on top.

Since the full Moon is the brightest, you might expect it to be easy to see by day, but you almost never can. It sits opposite the Sun, so it rises only around sunset. The Moon you see longest in daylight is the half Moon. Around the 7th or 8th day of the lunar month, the first quarter Moon rises at midday and hangs in the eastern to southern sky all afternoon. Around the 22nd or 23rd day, the last quarter Moon rises around midnight and stays in the southern to western sky through the morning. Near the crescent phase, the Moon is too close to the Sun and gets lost in its glare.

Checking the lunar date in a calendar app makes it easier to guess when to look. A half Moon sits about 90 degrees from the Sun in the sky, so if you turn your back to the Sun and look up a little, it comes into view. Near first quarter, look at the eastern sky in the afternoon; near last quarter, look at the western sky in the morning. The clearer and cleaner the air, the easier it is to see.

Take care not to look straight at the Sun while you search. If you want a photo, tap the Moon on your screen to set focus and brightness, and you'll capture its shape instead of a white dot.