Diameter of Earth - Definition, Examples, Quiz, FAQ, Trivia
Discover how we measure the size of our planet and compare it to others!
Understanding Earth's Diameter
The diameter of Earth is the distance from one side of the planet to the other, passing straight through the center. Earth isn't a perfect sphere - it's slightly flattened at the poles and bulging at the equator because of its rotation.
We measure Earth's diameter in two ways:
• Equatorial diameter: Across the widest part at the equator
• Polar diameter: From the North Pole to the South Pole
Size Fact!
Earth's equatorial diameter is about 43 kilometers (27 miles) larger than its polar diameter because of the centrifugal force from Earth's rotation!
Measuring Earth's Size
Earth's size can be described in several ways:
Diameter
Equatorial: 12,756 km (7,926 miles)
Polar: 12,714 km (7,900 miles)
Radius
Half the diameter
Average: 6,371 km (3,959 miles)
Circumference
Around the equator:
40,075 km (24,901 miles)
These measurements help scientists understand Earth's shape, which is called an oblate spheroid. This means it's almost a perfect sphere but slightly flattened at the poles and bulging at the equator.
Mass and Density
Earth has a mass of 5.97 × 10²⁴ kg and density of 5.52 g/cm³. This density creates gravity that keeps us firmly on the ground!
Comparing Earth to Other Planets
Earth is the fifth largest planet in our solar system. Let's see how it compares to others:
Real World Example
In 1996, scientists discovered a new planet with a diameter that's 5.86% of Earth's diameter. Earth's diameter is 12,756,000 meters. How large is this new planet?
Step 1: Convert percentage to decimal: 5.86% = 0.0586
Step 2: Multiply Earth's diameter by the decimal:
12,756,000 m × 0.0586 = 747,861.6 meters
Step 3: Convert to kilometers: 747,861.6 m = 747.86 km
This new planet is only about 748 km in diameter - smaller than Earth's moon!
Earth's Size Quiz
Test your knowledge about Earth's diameter and size with this quiz!
Frequently Asked Questions
Here are answers to common questions about Earth's diameter:
Space Size Trivia
Discover amazing facts about Earth's size and space measurements!
Tallest Mountain
Mount Everest is 8.8 km tall, but that's only 0.14% of Earth's diameter. If Earth were the size of a basketball, Everest would be just a tiny scratch on its surface!
Walking Around Earth
If you walked non-stop at 5 km/h (3 mph), it would take about 334 days to walk around Earth at the equator! You'd need to walk for nearly a year without stopping.
View from Space
Astronauts in the International Space Station (400 km up) can see Earth's curvature clearly. From the Moon (384,000 km away), Earth appears about the size of a marble.
Solar System Size
About 1.3 million Earths could fit inside the Sun! Jupiter, the largest planet, could hold 1,321 Earths. Our solar system is mostly empty space between planets.
