Moonrise and moonset are times when the upper

limb Limb may refer to: Science and technology *Limb (anatomy), an appendage of a human or animal *Limb, a large or main branch of a tree *Limb, in astronomy, the curved edge of the apparent disk of a celestial body, e.g. lunar limb *Limb, in botany, t ...

of the

Moon The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Earth diameter, Earth's diameter). The Moon rotation, rotates, with a rotation period (lunar ...

appears above the

horizon The horizon is the apparent curve that separates the surface of a celestial body from its sky when viewed from the perspective of an observer on or near the surface of the relevant body. This curve divides all viewing directions based on whethe ...

and disappears below it, respectively. The exact times depend on the

lunar phase A lunar phase or Moon phase is the apparent shape of the Moon's directly sunlit portion as viewed from the Earth. Because the Moon is tidally locked with the Earth, the same hemisphere is always facing the Earth. In common usage, the four maj ...

and

declination In astronomy, declination (abbreviated dec; symbol ''δ'') is one of the two angles that locate a point on the celestial sphere in the equatorial coordinate system, the other being hour angle. The declination angle is measured north (positive) or ...

, as well as the observer's location. As viewed from outside the

polar circle A polar circle is a geographic term for a conditional circular line (arc) referring either to the Arctic Circle or the Antarctic Circle. These are two of the keynote circles of latitude (parallels). On Earth, the Arctic Circle is currentl ...

s, the Moon, like all other celestial objects outside the circumpolar circle, rises from the

east East is one of the four cardinal directions or points of the compass. It is the opposite direction from west and is the direction from which the Sun rises on the Earth. Etymology As in other languages, the word is formed from the fact that ea ...

ern half of the horizon and sets into the

west West is one of the four cardinal directions or points of the compass. It is the opposite direction from east and is the direction in which the Sun sets on the Earth. Etymology The word "west" is a Germanic word passed into some Romance langu ...

ern half due to

Earth's rotation Earth's rotation or Earth's spin is the rotation of planet Earth around its own Rotation around a fixed axis, axis, as well as changes in the orientation (geometry), orientation of the rotation axis in space. Earth rotates eastward, in progra ...

Direction and time

Direction

Since Earth rotates eastward, all celestial objects outside the circumpolar circle (including the

Sun The Sun is the star at the centre of the Solar System. It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light a ...

, Moon, and

star A star is a luminous spheroid of plasma (physics), plasma held together by Self-gravitation, self-gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night sk ...

s) rise in the east and set in the west for observers outside the

s. Seasonal variation means that they sometimes rise in the east-northeast or east-southeast, and sometimes set in the west-southwest or west-northwest. This north-south variation of the point along the horizon is bookended by two

lunar standstill A lunar standstill or lunistice is when the Moon reaches its furthest north or furthest south point during the course of a month (specifically a tropical month of about 27.3 days). The declination (a equatorial coordinate system, celestial coord ...

s or turnarounds, the directions of which are sometimes depicted in archaeoastronomical constructions. It takes 18.6 years for the Moon to traverse this variation viewed from a vantage point on Earth.

Time

The Moon's position relative to Earth and the Sun determines the moonrise and moonset time. For example, a last quarter rises at

midnight Midnight is the transition time from one day to the next – the moment when the date changes, on the local official clock time for any particular jurisdiction. By clock time, midnight is the opposite of noon, differing from it by 12 hours. ...

and sets at

noon Noon (also known as noontime or midday) is 12 o'clock in the daytime. It is written as 12 noon, 12:00 m. (for '' meridiem'', literally 12:00 midday), 12 p.m. (for ''post meridiem'', literally "after midday"), 12 pm, or 12:00 (using a 24-hour cl ...

. A waning gibbous is best seen from late

night Night, or nighttime, is the period of darkness when the Sun is below the horizon. Sunlight illuminates one side of the Earth, leaving the other in darkness. The opposite of nighttime is daytime. Earth's rotation causes the appearance of ...

to early

morning Morning is either the period from sunrise to noon, or the period from midnight to noon. In the first definition it is preceded by the twilight period of dawn, and there are no exact times for when morning begins (also true of evening and nigh ...

. The Moon rises 30 to 70 minutes later each

day A day is the time rotation period, period of a full Earth's rotation, rotation of the Earth with respect to the Sun. On average, this is 24 hours (86,400 seconds). As a day passes at a given location it experiences morning, afternoon, evening, ...

/night than the day/night before, due to the fact that the Moon moves 13 degrees every day. Hence, the Earth must move 13 degrees after completing one rotation for the Moon to be visible.

Visual appearance

The Moon appears to be larger at moonrise or moonset due to an illusion. This illusion, known as the

Moon illusion The Moon illusion is the optical illusion of the Moon appearing larger near the horizon than it does higher up in the sky. It has been known since ancient times and recorded by various cultures. The explanation of this illusion is still debate ...

, is caused by an effect of the

brain The brain is an organ (biology), organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It consists of nervous tissue and is typically located in the head (cephalization), usually near organs for ...

. There is no definitive explanation for the Moon illusion. However, it is most likely because of how the brain perceives objects at different distances, and/or the distance we expect objects to be from us when they are near the horizon. The Moon appears to be more yellowish near the horizon. This is for the same reason the Sun and/or sky appears to be orangey-red at sunrise/sunset. When the Moon appears near the horizon, the light coming from it has to pass through more layers of atmosphere. This scatters the blue away, and leaves yellow, orange, and red. This is also the reason the Moon appears red during a deep partial or total

lunar eclipse A lunar eclipse is an astronomical event that occurs when the Moon moves into the Earth's shadow, causing the Moon to be darkened. Such an alignment occurs during an eclipse season, approximately every six months, during the full moon phase, ...

Notes

References

{{The Moon Orbit of the Moon Daily events