Guides
Where is the Moon right now?
The Moon is not always up when it is dark, and it is often up when it is light. Where it stands at this moment follows from one thing: its phase, which fixes its position relative to the Sun.
The phase tells you the hour
The Moon rises in the east and sets in the west, like the Sun, carried by the Earth's rotation. What changes over the month is when. A new moon travels with the Sun: up all day, down all night, and invisible in the glare. A full moon stands opposite the Sun: it rises as the Sun sets and sets as the Sun rises. The quarters sit halfway. The table gives the pattern, to the nearest hour or so, in solar time (midday being the moment the Sun is highest).
| Phase | Rises | Highest | Sets |
|---|---|---|---|
| New moon | Sunrise | Midday | Sunset |
| First quarter | Midday | Sunset | Midnight |
| Full moon | Sunset | Midnight | Sunrise |
| Last quarter | Midnight | Sunrise | Midday |
Between these four, the Moon rises later each day, by about 50 minutes on average. The delay is not constant: it can be as short as half an hour or longer than an hour, depending on the season and your latitude. The famous Harvest Moon is simply the full moon whose day-to-day delay is shortest, so that it rises at dusk several evenings running.
Which direction to look
Roughly east when it rises, roughly west when it sets. The exact point on the horizon swings north and south over the month, in the same way the Sun's rising point swings over the year, only a little further. At the middle latitudes of the northern hemisphere the Moon crosses the sky in the south, standing highest when it is due south; in the southern hemisphere it crosses through the north. Near the equator it passes almost overhead.
The full moon of winter rides high, because it stands opposite a low Sun; the full moon of summer stays low for the same reason. A crescent is always found near the Sun: the waxing crescent low in the west after sunset, the waning crescent low in the east before dawn.
Why the Moon is out in daytime
Most days of the month the Moon is above the horizon for part of the daylight hours; the full moon is the only phase that is up all night and down all day. A first-quarter Moon rises around midday and is easy to find in the afternoon sky, pale against the blue. A last-quarter Moon is the one you see on a morning walk. Neither is unusual: the Moon is simply following the schedule in the table.
Why some nights it is nowhere
- Within a day or two of new moon, it is in the daytime sky next to the Sun, and the lit side faces away from you.
- In the evening during the second half of the month, a waning Moon has not risen yet: it comes up late, sometimes after midnight.
- In the early evening during the first half, a waxing crescent may already have set, following the Sun down within a few hours.
- Clouds, of course. The Moon is bright enough to show through thin cloud as a glow, which is enough to locate it.
Questions
- Why can't I see the Moon tonight?
- Either it is near new moon and lost beside the Sun, or it has not risen yet: in the second half of the lunar month the Moon rises late in the evening or after midnight. Check the phase, then the table above.
- Does the Moon always rise in the east?
- Roughly, yes: somewhere between north-east and south-east, and the point shifts over the month. It never rises in the west; the Earth's rotation carries it the same way as the Sun.
- Why does the Moon look bigger near the horizon?
- It is not bigger; a camera proves it. The Moon illusion is a trick of perception, probably because the eye compares the Moon with distant objects on the horizon. Its true apparent size only changes with its distance, by about 14% between the closest and farthest points of its orbit.
- How fast does the Moon move across the sky?
- About 15 degrees an hour westward, with the whole sky, from the Earth's rotation. Against the stars it drifts eastward by about its own diameter every hour, a little over 13 degrees a day, which is why it rises later each day.