The Lemon-Shaped Moon: Surprising Celestial Facts

Source: Current Moon – June 15, 2011 _ Current moon as viewed on Wed… _ Flickr

Introduction

Though the Moon has been watched and studied for centuries, it still holds many interesting facts not known to the people. One is in the shape of the moon. Most people claim that the Moon is not perfectly round. It is really so, because its equator bulges like a lemon. Such an interesting phenomenon resulted from gravitational action between the Moon and Earth.

The Gravitational Dance

It follows an elliptical curve instead of a circular orbit while it orbits Earth. That means that at times it appears closer to Earth than at others. Variation in distance gravely impacts the gravitational forces acting on the Moon.

In this way, because the Moon is closer to Earth when this happens, the pull is stronger. This stretching of the Moon along the axis connecting its center to Earth causes a greater force to be exerted outwardly on its equatorial region in this manner, which bulges it.

Conversely, this weaker pull when the moon is far away from Earth relaxes the bulge of the equatorial region of the moon just a little.

Tidal Forces and the Shape of the Moon

Tidal forces that exist between the Earth and the Moon also force tides on our planet. This, in turn, is what decisively influences the shape of the Moon.

The gravitational pull exerted by the Moon on Earth would cause the oceans to bulge. On one side of Earth it created a bulge, and on the opposite side of Earth, another bulge formed. Thus, these bulges of water produce a gravitational force of attraction on the Moon causing it to rotate slightly faster.

This faster rotation leaves an insinuation on the form of the Moon. The poles are flattened and the equator expanded, which contributes to a lemon-shaped bulge.

Internal Structure of the Moon

The internal structure also determines the shape of the Moon. Scientists assume that the Moon contains a solid inner core, a liquid outer core, and a mantle. The spread of mass in these layers can affect the shape of the Moon.

If the Moon is not an evenly mass-distributed body, then its gravitational field may be responsible for anomalies that affect the way the bulge is being formed around the equator. However, specific details about this are still subject to scientific studies regarding the internal structure of the Moon and how it influences its own shape.

Observation of the Shape of the Moon

It is not visible so easily by the naked eye, but its existence is quite prominent if measured with much accuracy and instruments. Astronomers may make use of high-resolution cameras attached to their telescopes to capture the pictures of the Moon for better analysis of the shape of the Moon.

In addition, orbiters around the Moon, such as the Lunar Reconnaissance Orbiter (LRO), have provided long measurements of the topography of the surface of the Moon. These measurements tell a lot about how the Moon is shaped and what forms beneath its surface.

Knowing how the Moon is Shaped

The subject of the Moon’s shape is not only a scientific curiosity. It has practical application besides scientific interest. For instance, knowing what shape the Moon assumes is of great importance to future missions to the Moon, such as a lunar base or a spacecraft landing.

Understanding the lunar gravitational field and how it varies across the lunar surface will also help the astronomers to make more precise predictions over the spacecraft trajectory so that it can be landed safely. Furthermore, the shape of the Moon may be able to provide some information relating to the history of Moon’s formation and evolutions within our solar system. The Changing Shape of the Moon

While the Moon’s lemon-shaped bulge is a pretty prominent feature, it must be noted that this characteristic is dynamic rather than static. That is to say, the shape of the Moon actually keeps changing due to the following reasons, among others:

Tidal Dissipation As the Moon orbits Earth, it exerts tidal forces on our planet, causing Earth’s rotation to slow down. In compensation, the Moon’s orbit is slowly increasing away from Earth. This process, called tidal dissipation, is also making the Moon slow its rotation about the axis. In other words, the Moon is slowly getting a spherical shape.
Internal Structure: Since the Moon has an internal structure, it could also be causing the shape. For instance, if the inside core of the Moon is cooling down and is becoming solid, then it will make the Moon shrink. Due to this shrinking, the shapes within the Moon would be altered.
Impact Effects: The surface of the Moon is loaded with impact effects. These impacts lead to local alterations within the crust of the Moon through deformations. This would naturally affect the overall shapes within the Moon.

The Role of the Moon in Shaping Earth’s Orbit

Since the shape of the Moon has played the most important role in modeling Earth and keeping it intact as far as rotation and nearly constant climate are concerned, it also affects the development of oceans and continents on Earth.

The shape of the Moon also hints at some facts regarding the habitability of Earth. The tidal forces caused by the Moon allow for circulation of water in oceans, supporting life. Moreover, the gravity by the Moon may have protected the Earth from destructive space debris.

Future Study on Moon’s Shape

Although many aspects have been achieved regarding the understanding of the shape of the Moon, several questions still surface and continue to appear with a view that there is much left yet to be revealed. Future developments and further research are going to focus on the following fields:

Precise Measurement of the Shape of the Moon: There will be continued usage of more advanced instruments in the measurement of the shape of the Moon. This means further refined understanding of the forces that are currently shaping the Moon.
Study of the internal structure: The scientists will get deeper knowledge about how the Moon is evolving over time as far as the internal structures are concerned.
Investigating the shape of the Moon based on impact events: This will enable a look at the role played by impact events in shaping the surface and the overall shape of the Moon.
Exploring Possibilities For Future Lunar Visits: The more we know the shape of the Moon and its underlying processes, the sooner we can start planning for such future lunar missions, like launching a lunar base or landing a spacecraft in the Moon’s soil.

Conclusion

The shape of the Moon is not only a very interesting thing but also a complex phenomenon, just like its repercussions on the Moon itself, it also impacts the Earth. There is a possibility of learning something from the various shapes of the Moon about the forces which shaped our solar system, about the interactions currently shaping the evolution of our celestial bodies. The more we learn about the shape of the Moon, the more astonishing and interesting facts hidden in this mysterious satellite.

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