What Is The Size Of Earth Compared To Other Planets? Earth, our home, may feel vast, but its size is relative when compared to other celestial bodies in our solar system. COMPARE.EDU.VN provides a detailed comparison to help you visualize Earth’s position among planets and offers comprehensive analysis on planetary dimensions, volume, and key attributes. Explore Earth’s planetary comparison, along with details on planetary dimensions, to gain a clearer understanding of our place in the cosmos.
1. What Is Earth’s Size and Shape?
Earth is the fifth-largest planet in our solar system, but what are its exact dimensions and how does its shape influence its size? The Earth isn’t a perfect sphere; it’s an oblate spheroid, bulging at the equator due to its rotation. This bulge affects measurements like radius and circumference.
- Equatorial Radius: 3,963 miles (6,378 kilometers)
- Polar Radius: 3,950 miles (6,356 kilometers)
- Diameter (through the center): 7,926 miles (12,756 km)
- Equatorial Circumference: 24,901 miles (40,075 km)
- Meridional Circumference (North Pole to South Pole): 24,860 miles (40,008 km)
2. Who First Measured the Earth and How?
The quest to determine Earth’s size dates back to ancient times. Discover how early thinkers approached this challenge and laid the foundation for modern geodesy.
2.1. Aristotle’s Estimation
Greek philosopher Aristotle made one of the earliest attempts to measure Earth’s circumference, estimating it to be about 45,500 miles (73,225 km), according to NOAA.
2.2. Eratosthenes’ Accurate Measurement
Around 250 B.C., Eratosthenes used trigonometry to measure the distance between Aswan and Alexandria by measuring the sun’s position at the same time in both locations. Using this, along with basic geometry, he calculated Earth’s circumference to within 1% accuracy. This method became the basis of geodesy, the science of measuring Earth’s size, geometric shape, orientation in space, and gravitational field.
3. Why Is Earth Bigger at the Equator?
The equatorial bulge is a direct result of Earth’s rotation. Explore the physics behind this phenomenon and its effects on gravity.
3.1. Rotational Forces and the Bulge
Earth’s rotation causes it to bulge at the equator and flatten at the poles. The rotational speed is faster at the equator than at the poles, as is true for all rotating spheres. This also means that the gravitational pull of Earth is slightly weaker at the equator than at the poles.
4. What Are Earth’s Volume, Mass, Density, and Surface Area?
Beyond its dimensions, understanding Earth’s physical properties provides a more complete picture of its size and composition.
4.1. Key Physical Properties
- Volume: 260 billion cubic miles (1.086 trillion cubic kilometers)
- Mass: 6.6 x 10^21 tons (6 x 10^21 metric tons)
- Density: Around 5.5 grams per cubic centimeter
- Surface Area: 197 million square miles (510 million square kilometers)
- Land: 57 million square miles (148 million square km), or 29%
- Water: 140 million square miles (362 million square km), or 71%
4.2. Extreme Points on Earth
- Highest Point (Altitude Above Sea Level): Mount Everest at 29,029 feet (8,848 meters)
- Farthest Point from Earth’s Center: Mount Chimborazo, with its summit over 6,800 feet (2,073 m) farther from Earth’s center than Mount Everest’s summit
5. Earth Compared to Other Planets: An Overview
How does Earth stack up against its planetary neighbors? Here’s a comparative look at the sizes of planets in our solar system.
5.1. Ranking in the Solar System
Earth is the fifth-largest planet in the solar system, following Jupiter, Saturn, Uranus, and Neptune.
6. How Does Earth Compare to the Gas Giants (Jupiter, Saturn, Uranus, Neptune)?
The gas giants dwarf Earth in size. Let’s examine these differences more closely.
6.1. Jupiter: The Giant
Jupiter, the largest planet in the solar system, has a diameter of 86,881 miles (139,822 km), making it 11 times wider than Earth. Its volume is 343 trillion cubic miles (1,431 trillion cubic kilometers), meaning it would take about 1,320 Earths to fill Jupiter’s volume. If Earth were the size of a grape, Jupiter would be the size of a basketball.
6.2. Neptune: The Fourth Largest
Neptune has a diameter of 30,599 miles (49,244 km), about four times as wide as Earth. It would take 57 Earths to fill Neptune’s volume. If Earth were the size of a nickel, Neptune would be the size of a baseball.
7. Earth vs. Inner, Rocky Planets (Mercury, Venus, Mars)
Earth is the largest of the inner, rocky planets. Let’s see how it compares to Venus, Mars, and Mercury.
7.1. Venus: Earth’s Closest Sibling in Size
Venus is the second largest rocky planet, slightly smaller than Earth.
7.2. Mars: The Red Planet
Mars is significantly smaller than Earth, with a thinner atmosphere and lower density.
7.3. Mercury: The Smallest
Mercury has a diameter of 3,032 miles (4,879 km), about one-third the size of Earth. Earth and Mercury are the densest planets in the solar system, with densities similar to that of the iron-rich mineral hematite.
8. What Accounts for Earth’s High Density?
Earth’s core plays a crucial role in its overall density. Explore the composition and properties of Earth’s inner layers.
8.1. Composition of Earth’s Core
The high density of Earth is due to its core, which has a diameter of about 7,000 miles (11,265 km) and is made of 80% iron and around 5% nickel, along with lighter elements like carbon, oxygen, silicon, or sulfur.
- Inner Core Density: As great as 12.2 grams per cubic centimeter
- Outer Core Density: Around 13 grams per cubic centimeter
9. Expert Insights: Simon Lock on Planetary Sizes
Get expert opinions on Earth’s size and its comparisons with other planets from Simon Lock, a research fellow at the University of Bristol.
9.1. Exact Size of Earth
From the Earth’s center to its surface (radius) is 6,378 km (3,963 miles).
9.2. Comparison with Other Planets
Earth is the largest of the rocky, terrestrial planets. Mercury is only 40% the radius of Earth, while Jupiter is 11 times bigger.
9.3. Earth-Like Planets Outside the Solar System
Planets with similar mass and composition to Earth are likely relatively common in other solar systems. However, those found so far are typically too close to their stars to host liquid water oceans. Many factors make Earth special, including magnetic fields and stabilizing moons.
9.4. Studying Earth’s Dynamics
Scientists study Earth’s dynamics through rock chemistry, earthquake waves, and material behavior under high pressures and temperatures. Theorists build models using physics and chemistry, constrained by empirical data.
10. Additional Resources for Understanding Earth’s Size
Explore these resources to deepen your understanding of Earth’s size and its place in the universe.
10.1. Earth’s Formation
Khan Academy explains the formation of our planet, detailing how it reached its current size.
10.2. Brown Dwarfs
A NASA simulation replicates conditions across brown dwarfs, showing the limit to how big planets can get before becoming “failed stars.”
10.3. Black Holes
Tour the universe’s largest black holes and compare them with distances in our solar system via a NASA simulation.
11. Frequently Asked Questions (FAQs) About Earth’s Size
Get quick answers to common questions about Earth’s dimensions and comparisons with other planets.
11.1. What is the exact circumference of the Earth?
The Earth’s equatorial circumference is approximately 24,901 miles (40,075 kilometers).
11.2. How does Earth’s size compare to the Moon?
Earth is much larger than the Moon. About 50 Moons could fit inside Earth.
11.3. Which planet is closest in size to Earth?
Venus is the planet closest in size to Earth, with a diameter only slightly smaller than Earth’s.
11.4. How much of Earth’s surface is covered by water?
Approximately 71% of Earth’s surface is covered by water.
11.5. What is Earth’s position in terms of distance from the Sun?
Earth is the third planet from the Sun in our solar system.
11.6. How does Earth’s density compare to other planets?
Earth is one of the densest planets in the solar system, second only to Mercury.
11.7. What is the highest point on Earth, and how does it compare to the tallest mountain on Mars?
The highest point on Earth is Mount Everest. The tallest mountain on Mars, Olympus Mons, is much larger.
11.8. How did scientists first calculate the size of Earth?
Eratosthenes was one of the first to accurately calculate Earth’s circumference using basic geometry and observations of the sun.
11.9. Why is Earth considered habitable?
Earth’s size, distance from the Sun, atmosphere, and presence of water make it habitable for life.
11.10. How does Earth’s size affect its gravitational pull?
Earth’s size and mass determine its gravitational pull, which is strong enough to hold onto its atmosphere and oceans.
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13. References
- Densities of Solar System Planets, Open University, [accessed 10/20/23]
- Earth Fact Sheet, NASA, [accessed 10/20/23]
- How large is Earth? CalTech Cool Cosmos, [accessed 10/20/23]
- The History of Geodesy, NOAA,
