Why are day and year on the moon the same length?

Answer 1

Some basics about the movement of the moon: The moon orbits around the earth. One orbit around the earth is commonly called a lunar cycle. The word 'month' derives from the word 'moon', and refers to this lunar cycle of roughly 29 days. The moon does not orbit around the sun independent of earth. The moon does orbit around the sun, but only because the moon orbits the earth and accompanies the earth in its yearly journey around the sun. These are just the basics; we won't get into precise definitions of orbital periods, or percise lengths of time of various movements. The moon also rotates on its axis, and it completes one rotation during the course of one lunar orbit around the earth. This is because the moon's orbit around the earth is 'tidally locked' with the planet earth. Because the moon rotates one full time during the course of one lunar cycle, the lunar 'day' is the same length as a lunar cycle. What we observe as the phases of the moon really is the unfolding of one lunar day on the moon's surface. Also, the fact that one rotation on the moon's axis is equal to on lunar orbit around the earth is what causes the same face to always face earth (with some slight differences that we won't cover here). The lunar day, then, is one lunar cycle (roughly a month) long. A lunar year, if measured by the moon's orbit of the sun, is the same length as an earth year.

Answer 2

Let us define what we mean by 'day' and 'year' in general. For orbiting, rotating bodies, a 'day' refers to the time taken to complete one revolution on a body's axis. A 'year' refers for the time taken to make one complete orbit around the body which it is orbiting.

In the case of the moon, which orbits the earth, a lunar 'year' is the time it takes for the moon to move around the earth (about one earth month). The moon is tidally locked to the earth, which means that the same side of the moon always faces the earth as it rotates around. The moon will, therefore, complete one full rotation on its own axis for every one orbit that it makes of the earth. This makes the 'year' the same length as the 'day'.

This phenomenon of tidal locking can be observed in other moons in our solar system, such as Saturn's moon Titan.

Answer 3

The Earth's moon has a period of rotation (day) that is exactly as long as its "year" which is Earth's "month", the time it takes for the Moon to travel completely around Earth in its orbit), which is 27.3 Earth days. It is theorized that the relatively close configuration of its Earth orbit produced tidal friction with the slight "bulge" of the Moon toward the gravity pull of the Earth. As the bulge rotated away from the direct line to the Earth, it created torque that slowed the Moon's rotation. This continued until the bulge kept a nearly constant position, i.e. always facing the Earth, eliminating the torque.

Answer 4

They aren't. The lunar day is about four Earth weeks. Since the Moon travels along with the Earth, it takes it as long to go around the sun as the Earth does, one "year". That is what a year *is*. Generally speaking, if I remember correctly, the Moon goes through just about 13 "lunar days" in one year.

Answer 5

This is because the moon is on a 90 degree axis. This means there are no seasons so the sun always stays in the same position in the sky. On Earth the sun gradually goes from North to South in the sky over the seasons. This, due to the Earth 's axis causes the days in the summer when the sun is high in the sky to be longer. The sun is always high in the sky on the moon.

Answer 6

it's because the moon is tidally locked to the earth, with the near side always facing the planet the moon completes only 1 rotation for every time it goes around the earth.

Answer 7

No. The Moon travels with the Earth; once around the Sun is one year for both. A lunar day and night are around four Earth weeks long.

Answer 8

The length of the Moon's day is about 29.5 of our days. The length of the Moon's year is the same as ours - 365.24 of our days, or a little over 12 "Moon days".

Answer 9

They aren't.

Answer 10

It isn't.