How big is Earth’s Moon compared to other moons in our solar system? COMPARE.EDU.VN offers a detailed comparison, revealing that while our Moon is significant, it’s not the largest. Understand lunar dimensions and discover how it stacks up against other celestial bodies, gaining valuable insights into our cosmic neighborhood and moons in general.
1. Understanding the Size of Earth’s Moon
Earth’s Moon is a captivating celestial object that illuminates our night sky. To truly appreciate its significance, we must first understand its dimensions. The Moon’s mean radius is approximately 1,079.6 miles (1,737.5 kilometers), and its mean diameter measures 2,159.2 miles (3,475 km), according to NASA. This makes it substantially smaller than Earth, roughly a quarter of our planet’s size. The moon’s equatorial circumference is 6,783.5 miles (10,917 km). While it may appear large from our perspective, that’s primarily because it’s our closest celestial neighbor, averaging around 238,855 miles (384,400 km) away.
The moon is a little more than one quarter the size of Earth, highlighting the size differences.
1.1 Key Statistics of Earth’s Moon
Here’s a quick rundown of vital statistics concerning the Moon:
- Radius: 1,079.6 miles (1,737.5 km)
- Diameter: 2,159.2 miles (3,475 km)
- Surface Area: 14.6 million square miles (38 million square km)
- Mass: 7.35 x 10^22 kg
- Density: 3.34 grams per cubic centimeter (3.34 g/cm3)
The Moon’s surface area is considerable, though smaller than the continent of Asia, which spans 17.2 million square miles (44.5 million square km).
2. How Earth’s Moon Compares to Other Moons in the Solar System
While Earth’s Moon appears large and prominent in our sky, it is only the fifth-largest moon in our solar system. According to The Nine Planets, it stands out because of its size relative to Earth. But when compared to other moons orbiting different planets, its size is quite average. Let’s delve into how it measures up against some of the larger moons.
2.1 The Giants: Ganymede and Titan
Topping the list are Jupiter’s Ganymede and Saturn’s Titan. Ganymede, the largest moon in the solar system, boasts an equatorial radius of 1,635 miles (2,631 km). Titan follows closely with a radius of 1,600 miles (2,575 km). Both dwarf Earth’s Moon, showcasing the sheer diversity in lunar sizes throughout our solar system.
2.2 Other Notable Moons
Other significant moons include Jupiter’s Callisto, with a radius of 1,497 miles (2,410.3 km), and Io, at 1,131.7 miles (1,821.6 km). Even Jupiter’s Europa, with a radius of 969.84 miles (1,560.8 km), is quite close in size to our Moon. Neptune’s Triton and Uranus’ Titania and Oberon are also larger than Earth’s Moon.
3. Detailed Comparison Table of the Largest Moons
To provide a clearer comparison, here’s a table showing the sizes of the ten largest moons in our solar system:
| Rank | Moon | Equatorial Radius | Parent Planet |
|---|---|---|---|
| 1 | Ganymede | 1,635 miles (2,631 km) | Jupiter |
| 2 | Titan | 1,600 miles (2,575 km) | Saturn |
| 3 | Callisto | 1,497 miles (2,410.3 km) | Jupiter |
| 4 | Io | 1,131.7 miles (1,821.6 km) | Jupiter |
| 5 | The Moon | 1,079.6 miles (1,737.5 km) | Earth |
| 6 | Europa | 969.84 miles (1,560.8 km) | Jupiter |
| 7 | Triton | 840.96 miles (1,353.4 km) | Neptune |
| 8 | Titania | 490.19 miles (788.9 km) | Uranus |
| 9 | Rhea | 474.91 miles (764.3 km) | Saturn |
| 10 | Oberon | 473.11 miles (761.4 km) | Uranus |
This comparison vividly illustrates that while our Moon is substantial, it doesn’t dominate the charts regarding absolute size.
4. Mass, Density, and Gravitational Force
Beyond size, mass, density, and gravitational force are crucial factors in understanding a moon’s characteristics.
4.1 Moon Mass and Density
The Moon’s mass is approximately 7.35 x 10^22 kg, about 1.2% of Earth’s mass. Earth, therefore, weighs 81 times more than the Moon. Its density is around 3.34 grams per cubic centimeter (3.34 g/cm3), roughly 60% of Earth’s density.
4.2 Gravitational Differences
The Moon’s gravitational force is only about 16.6% of Earth’s gravity. This means that an individual would weigh six times less on the Moon than on Earth. For instance, a 45-kilogram person would weigh 100 lbs on Earth but only 16.6 lbs on the Moon. This stark difference would make events like long jumps incredibly exciting on the lunar surface.
4.3 Mapping Lunar Gravity
In 2012, NASA’s Gravity Recovery and Interior Laboratory (GRAIL) mission meticulously mapped the Moon’s gravity, offering unprecedented detail. Maria Zuber of MIT noted that the Moon’s gravity field closely reflects its surface topography, allowing scientists to link changes in gravity with surface features such as craters, rilles, and mountains.
The Deep Space Climate Observatory satellite captured the moon and Earth together as the orbit of the satellite crosses the orbital plane of the moon, showcasing their relative sizes.
5. The Significance of the Moon
Despite not being the largest, the Moon holds immense scientific value. As Noah Petro of NASA’s Lunar Reconnaissance Orbiter (LRO) mission stated, “The moon is the Rosetta Stone by which we understand the rest of the solar system.” Its proximity and detailed study provide invaluable insights into the formation and evolution of celestial bodies.
5.1 Ongoing Research and Discoveries
Scientists continue to probe the Moon for more details, uncovering new information that enhances our understanding of space. The Moon’s accessibility makes it a prime target for ongoing missions and research.
6. The Illusion of Size: Supermoons and Horizon Views
Have you ever wondered why the Moon occasionally appears exceptionally large?
6.1 Understanding Supermoons
The Moon’s orbit around Earth is not perfectly circular; it’s elliptical. When the Moon is closest to Earth, about 226,000 miles (363,300 km), it is at its perigee. When a full moon coincides with perigee, we observe a supermoon, appearing 14 percent larger and 30 percent brighter than usual.
6.2 Supermoon Defined
The term “supermoon,” popularized by astrologer Richard Nolle in 1979, refers to a new or full moon within 90 percent of its closest approach to Earth. Astronomically, this phenomenon is termed a perigee-syzygy moon, where syzygy denotes the alignment of three celestial bodies – the Sun, Moon, and Earth.
6.3 The Moon Illusion
Another intriguing phenomenon is the Moon’s apparent size increase when it’s near the horizon. This is an optical illusion known as the moon illusion or the Ponzo illusion. Despite being observed since ancient times, there’s no definitive explanation. One theory suggests that our brains compare the Moon to distant objects on the horizon, like trees, making it appear larger.
A supermoon rises over Washington, appearing larger and brighter than usual due to its proximity to Earth.
7. Exploring Key Differences
Let’s explore some additional differences between Earth’s Moon and other moons in our solar system.
7.1 Geological Activity
Earth’s Moon is geologically inactive, meaning it does not experience volcanic activity or tectonic plate movement. In contrast, some moons, like Jupiter’s Io, are highly active. Io is known for its intense volcanic activity, making it one of the most geologically active objects in the solar system. This activity is due to tidal forces from Jupiter.
7.2 Atmospheric Conditions
Our Moon has a very thin atmosphere, often described as an exosphere, which provides little to no protection from solar radiation or meteoroids. Other moons, like Saturn’s Titan, possess significant atmospheres. Titan’s atmosphere is so dense that it obscures the moon’s surface and is composed mainly of nitrogen, with traces of methane and other hydrocarbons.
7.3 Surface Composition
The surface of Earth’s Moon is primarily composed of basalt and anorthosite, with varying amounts of minerals like olivine and pyroxene. Other moons have more diverse surface compositions. For example, Europa is believed to have a subsurface ocean of liquid water beneath an icy crust. The composition of Triton includes frozen nitrogen, methane, and water ice.
7.4 Orbital Characteristics
Earth’s Moon is tidally locked with Earth, meaning it always shows the same face to our planet. Other moons have different orbital characteristics. For instance, Neptune’s Triton has a retrograde orbit, meaning it orbits in the opposite direction of its planet’s rotation.
8. Earth’s Moon: Uniquely Influential
Despite not being the largest, Earth’s Moon has a profound impact on our planet.
8.1 Stabilizing Earth’s Axis
One of the most crucial roles of Earth’s Moon is stabilizing our planet’s axial tilt. Without the Moon, Earth’s axial wobble would be much more significant, leading to drastic climate changes over time. The Moon keeps Earth’s tilt relatively stable, contributing to predictable seasons and a more stable environment.
8.2 Tides
The Moon’s gravitational pull is the primary cause of tides on Earth. The gravitational interaction between the Earth and Moon causes the oceans to bulge, creating high tides. Tides are essential for marine ecosystems, influencing the distribution of nutrients and the life cycles of many marine species.
8.3 Cultural and Historical Significance
The Moon has been a source of wonder and inspiration throughout human history. It features prominently in mythology, folklore, and art across various cultures. Lunar cycles have also influenced calendars and agricultural practices for thousands of years.
9. FAQ: Frequently Asked Questions About Moons
9.1 What is the largest moon in the solar system?
The largest moon in the solar system is Ganymede, orbiting Jupiter. Its equatorial radius is 1,635 miles (2,631 km).
9.2 How does the size of Earth’s Moon compare to Ganymede?
Earth’s Moon has an equatorial radius of 1,079.6 miles (1,737.5 km), making it considerably smaller than Ganymede.
9.3 Why does the Moon appear larger on the horizon?
The Moon appears larger on the horizon due to an optical illusion known as the Ponzo illusion. Our brains compare the Moon to terrestrial objects, making it seem bigger.
9.4 What is a supermoon?
A supermoon occurs when a full moon coincides with the Moon’s closest approach to Earth (perigee), making it appear larger and brighter.
9.5 What is the mass of Earth’s Moon?
The mass of Earth’s Moon is 7.35 x 10^22 kg, which is about 1.2% of Earth’s mass.
9.6 How does the Moon affect tides on Earth?
The Moon’s gravitational pull is the primary cause of tides on Earth, creating high and low tides in our oceans.
9.7 Is Earth’s Moon geologically active?
No, Earth’s Moon is not geologically active. It does not have volcanic activity or tectonic plate movement.
9.8 What is the density of Earth’s Moon?
The density of Earth’s Moon is 3.34 grams per cubic centimeter (3.34 g/cm3).
9.9 How does the gravity on the Moon compare to Earth?
The Moon’s gravitational force is about 16.6% of Earth’s gravity, meaning objects weigh significantly less on the Moon.
9.10 Why is the Moon important for Earth?
The Moon stabilizes Earth’s axial tilt, helps create tides, and has been a source of cultural and historical significance throughout human history.
10. Discover More Comparisons at COMPARE.EDU.VN
Delving into the size of Earth’s Moon compared to other moons reveals the fascinating diversity within our solar system. While our Moon may not be the largest, its influence on Earth is undeniable. Want to explore more detailed comparisons and make informed decisions? Visit COMPARE.EDU.VN at 333 Comparison Plaza, Choice City, CA 90210, United States, or contact us on WhatsApp at +1 (626) 555-9090. Whether you’re comparing celestial bodies or everyday products, compare.edu.vn provides the insights you need. Explore now and enhance your knowledge!
