You can see the Moon during the day because it reflects sunlight and can be bright enough to stand out against the daytime sky. It also spends plenty of time above the horizon during daylight. In NASA's daytime-Moon explanation, scientist Sarah Noble describes this as an ordinary part of the Moon's changing position, rather than an unusual event.
The Moon doesn't need darkness to shine
Moonlight is reflected sunlight. Nighttime makes the contrast more obvious, but it does not supply the light. The same reflection occurs when the Sun is also above your horizon.
An illustrative analogy is a pale building against a bright sky: noticing it depends on contrast, not on the building producing its own light. The Moon is vastly farther away, but the distinction between reflecting light and generating it is the relevant point.
Its phase helps explain the timing
NASA's Moon phase guide gives approximate patterns: a first-quarter Moon rises around midday and sets around midnight; a last-quarter Moon rises around midnight and sets around midday. Those patterns create opportunities for afternoon or morning visibility.
A full Moon is roughly opposite the Sun in the sky and rises around sunset. The near-full Moon can appear before sunset in the preceding days or remain after sunrise in the following days. Exact local times vary.
Being above the horizon isn't enough
At new Moon, the Moon is near the Sun's direction from our perspective, while its illuminated side faces away from Earth. NASA describes this as the normally invisible phase. “Up during the day” and “easy to see during the day” are different claims.
For a useful observing note, record the date, local time, approximate phase, and whether clouds obstructed your view. A missing sighting alone doesn't tell you whether the Moon was below the horizon or simply difficult to notice.
Use local times for a particular day
The phase gives a rough pattern, not a personalized timetable. NASA notes that visibility also depends on time of year and location. Check local moonrise and moonset predictions for a specific outing, and keep any skywatching well away from the Sun's glare.
Keep exploring: Why the sky looks blue · Why sunset colors change.
