If the Sun Was a Basketball How Big Would the Moon Be?

Humans live in a vast universe. It is larger than anyone can comprehend. When thinking about the solar system, one can often misjudge the magnitude of the sun, moon, and earth. To truly understand the size and distance of these celestial bodies, it can be helpful to scale them back and picture them in your mind as everyday objects. 

If the sun were a basketball, the moon would be about the size of a green pea (¼ inch in diameter). A standard NBA basketball has a diameter of 24 centimeters (9.4 inches). The moon is about 0.26 percent the size of the sun. Multiply 24 centimeters by 0.026 to get 0.624 centimeters or 0.25 (¼) inch.

As you can tell, the sun dwarfs the moon. You may now be wondering what the importance of this information is or how big other objects in this model would be. Keep reading to learn more about how the solar system would look if the sun were the size of a basketball.

What is the Purpose of Knowing a Scalable Size Difference Between the Sun and Moon?

Many depictions you see of the solar system are not accurate. This can lead to many people being misinformed about the size and distance between the sun, stars, and planets. Below are just a few of the things one can gain with a more accurate understanding of the size and distance of celestial objects. 

  • A better understanding of space travel
  • A way to visualize the solar system
  • Fun thought experiments

Space Travel

For many people who are not astronomers or astronauts, it can be hard to understand space travel.

An accurate scale model can help you understand how far astronauts have to travel to get to the moon or why it has been so elusive to get a human to land on Mars.

Visualizing the Solar System

The sun and the moon are massive objects that are extremely distant from one another. It can be difficult to understand the size difference between the two.

Scaling things back to more relatable sizes can help you visualize objects you know so you can understand complex information better.  

It Makes You Think 

If the sun were a basketball and the moon were a pea, think about how small humans would be. This can be intimidating to think about, but you can also learn a lot. 

Despite being minuscule creatures in a giant universe, humans have truly accomplished a lot.

If the Sun Were a Basketball and the Moon Were a Pea, How Big Would Earth Be?

Earth is roughly 3.7 times bigger than the moon. If you take the earlier pea-sized moon calculation of 0.624 cm (0.25 inch), multiply that by 3.7 to get your answer for the earth. Multiply the moon’s 0.624 diameter times 3.7 to get 2.31 cm or 0.91 in. At just under an inch in diameter, the earth would be about the size of a cherry.

How Big Would Other Planets Be in This Model?

Now that you know the size of Earth in this model, it is much easier to calculate how big other planets would be if the sun were a basketball. You would make these calculations by finding the approximate size of each planet compared to Earth and then multiplying that figure by the size of Earth in this model (2.31 cm or 0.91 in).

PlanetSize Compared to EarthDiameter in This Model
Mercury0.38 the size of Earth0.88 cm (0.35 in)
Venus0.95 the size of Earth2.19 cm (0.86 in)
Mars0.53 the size of Earth1.22 cm (0.48 in)
Jupiter11.19 x larger than Earth25.85 cm (10.18 in)
Saturn9.4 x larger than Earth21.71 cm (8.55 in) 
Uranus4.04 x larger than Earth9.33 cm (3.67 in)
Neptune3.88 x larger than Earth8.96 cm (3.53 in)

If the Sun Were a Basketball, How Far Away Would It Be from the Earth and Moon?

On average, the earth and moon are approximately 93 million miles away from the sun. This is about 11,750 times the earth’s diameter. If you take the 0.91 in diameter found for this model, you can calculate what the distance would be. Multiply 0.91 in by 11,750 for a total of 10,692.5 inches, or 891 feet, or about 0.17 miles.

Keeping with the basketball theme, let’s see what the distance would be if the sun was the size of a basketball. Bearing in mind that a basketball court is 94 feet long, that means there would be a distance of around 10 basketball courts one after the other. This comes from multiplying the 94 feet per 10, making it 940, which is just a bit more than the 891 feet that we calculated in the previous paragraph.

How Does the Moon Completely Cover the Sun During a Solar Eclipse?

It may seem impossible that the moon (green pea) could fully cover the sun (basketball) during a solar eclipse. Even though the sun is bigger, it looks smaller since it is farther away. This is why you may have noticed that the sun and moon from your perspective on Earth seem very similar in size.

The possibility of a solar eclipse is known as a coincidence. Their varying sizes and distances from the earth end up causing them to perfectly line up during an eclipse. 

The Sun is Growing

A solar eclipse will not be possible forever because the sun is growing small amounts each year. Scientific studies have estimated that the sun will consume the earth billions of years from now. 

The humans alive today will not live to see this, but it is frightening to think about. That is why scientists and astronauts are working on space travel to other parts of the solar system. This is the cause of the quest for determining if life is sustainable on other planets. 

Expeditions to Mars are a good example of these efforts. It has been determined through research that there is a chance of being able to live on Mars. This would give us extra distance from the sun to maintain human life for a while longer. 

How Scientists Measure the Solar System

Scientists use high-powered telescopes in very precise manners to accurately measure the size and distance of objects in the solar system. 

  • They figure out the size by measuring the diameter of planets that they see through their telescope compared to their visual size in the sky. 
  • They can then measure distance by looking at how the planets revolve around the sun.
  • They figure out how often the planet, or other objects in space, revolves around the sun.
  • Then they use a complex formula to calculate the distance it would be from the sun and distances between other objects in space. 

Will Scientists Ever Be Able to Accurately Measure the Whole Universe?

It is unlikely that scientific research will ever deliver an accurate measurement of the entire universe. Since our minds struggle to comprehend these sizes, it is hard to come up with complex formulas that calculate that large of size and distance. This is why the universe is known as being infinite. 

It is also important to note that the universe is constantly expanding. 


If the sun were the size of a basketball, the moon would be a quarter inch in diameter or roughly the size of a pea. People tend to misunderstand the size differences of objects that make up the solar system, so learning this can be very beneficial in judging how much of a size difference there is in objects such as the sun and moon.

Humans live in an expansive universe full of objects so massive that it is a struggle to comprehend them. It is no wonder that inquiring minds try to scale down the sizes of these objects to make sense of them. An accurate solar model can be a great way to learn more about the solar system humans call home.

If you liked this post, be sure to check “Has a Basketball Team Ever Scored 0 Points?” & “Can Basketball Increase Height After 21?“.


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