Moon

Definition

The Moon is Earth's only natural satellite, a celestial body that orbits the planet and has a significant influence on various phenomena, including tidal forces. It is the fifth-largest moon in the Solar System and the largest relative to the size of its parent planet.

5 Must Know Facts For Your Next Test

1. The Moon's gravitational pull, along with the Sun's, is the primary cause of tidal forces on Earth, which result in the rise and fall of ocean tides.
2. The Moon's elliptical orbit around the Earth, combined with the varying distances between the Earth and Moon, leads to differences in the strength of the tidal forces experienced on Earth.
3. Tidal forces caused by the Moon's gravity also contribute to the Earth's slight bulge, known as the Earth's tidal bulge, which is oriented towards and away from the Moon.
4. The Moon's influence on Earth's rotation is another consequence of tidal forces, causing a gradual slowing of the Earth's rotation over time.
5. The regular cycle of the Moon's phases, from new moon to full moon and back, is a result of the Moon's orbit around the Earth and the relative positions of the Sun, Earth, and Moon.

Review Questions

• Explain how the Moon's gravitational pull contributes to the phenomenon of tides on Earth.
  • The Moon's gravitational attraction exerts a pull on the Earth and its oceans. This pull is strongest on the side of the Earth closest to the Moon, and weakest on the side farthest from the Moon. This difference in gravitational pull creates a bulge in the Earth's oceans, resulting in high tides on the side closest to the Moon and the side farthest from the Moon, and low tides in between. This cyclical rise and fall of the tides is a direct consequence of the Moon's gravitational influence on the Earth.
• Describe how the Moon's elliptical orbit and varying distance from the Earth affect the strength of tidal forces experienced on Earth.
  • The Moon's elliptical orbit around the Earth means that its distance from the Earth is constantly changing. When the Moon is closest to the Earth (perigee), its gravitational pull is strongest, and the tidal forces experienced on Earth are more pronounced. Conversely, when the Moon is farthest from the Earth (apogee), its gravitational pull is weaker, and the tidal forces are less intense. This variation in the Moon's distance from the Earth, and the corresponding changes in the strength of its gravitational pull, leads to differences in the magnitude of the tidal forces experienced on Earth over the course of the Moon's orbit.
• Analyze the relationship between the Moon's influence on Earth's rotation and the phenomenon of tidal forces.
  • The Moon's gravitational pull, which is the primary driver of tidal forces on Earth, also has a subtle but significant effect on the planet's rotation. The Earth's tidal bulge, oriented towards and away from the Moon, creates a slight drag on the planet's rotation. Over long timescales, this drag has caused the Earth's rotation to slow down, with the length of a day increasing by approximately 2.3 milliseconds per century. This gradual slowing of the Earth's rotation is a direct consequence of the tidal forces exerted by the Moon, demonstrating the profound influence the Moon has on various aspects of Earth's geophysical processes.

Related terms

Tidal Forces: The gravitational pull between the Moon and Earth that causes the rise and fall of tides, as well as other phenomena like Earth's bulge and the Moon's effect on Earth's rotation.

Gravitational Attraction: The force of gravity between the Moon and Earth that keeps the Moon in orbit and contributes to the tidal forces experienced on Earth.

Lunar Phases: The different appearances of the Moon as it orbits the Earth, caused by the relative positions of the Sun, Earth, and Moon, and the amount of the Moon's illuminated surface that is visible from Earth.