How to Explain to a Child Why the Sun and Moon Seem to Be the Same Size

We all know that the sun and moon are different sizes. But why do they appear to be the same size in the sky?

We at 5-Minute Crafts are going to try and find the answer to this difficult question.

Why the sun and the moon appear to be the same size

The moon is smaller than the sun but looks to be the same size because the moon is closer. There’s an amazing coincidence here. The diameter of the sun is around 400 times bigger than the diameter of the moon, and it’s around 400 times further from the Earth. This is why they seem to be around the same size. It’s interesting that it hasn’t always been like that. Tidal interactions make the moon spiral from the Earth by around 3.8 cm to 4 cm a year. In the distant past, the moon was close enough to Earth to block the sun. So our ancestors saw a completely different sky, with the moon dominating it.

So the answer to the question of why the sun and moon appear to be the same size is an optical illusion: the objects that seem near you look bigger. You can demonstrate this effect to a child by doing the experiment just below.

  • Take a coin and stretch out your arm. Ask someone to take a plate and stand at a different end of the room, holding it in a stretched hand. Let your child find the necessary position, coming closer to you or farther from you until the plate appears to be the same size as the coin.

The real sizes of space objects and distances between them

  • The sun is around 149 million km from our planet. It’s an average distance because the orbit of the Earth is an ellipse, not a perfect circle. At the beginning of January, when the Earth is in perihelion (the closest point of the orbit to the sun), our planet is within 147.09 million km from the sun. In July, when the Earth is in aphelion (the furthest point of the orbit from the sun), it’s 152.10 million km from the sun. So the distance between the Earth and the sun changes by 3% or 5 million km throughout the year. The diameter of the sun is around 1,392,000 km. The diameter of the Earth is just 12,742 km. In other words, around 109 Earths could be aligned on the front part of the sun. The volume of the sun is around 1,304,000 times bigger than the Earth. So an enormous number of Earth-like planets would fit inside the sun.
  • The biggest planet of our solar system is Jupiter, but it’s also much smaller than the sun. Even though the diameter of Jupiter is 11 times bigger than that of Earth, the sun’s diameter is still almost 10 times bigger than the diameter of Jupiter. The sun’s volume is 987 times bigger than that of Jupiter, which is 1,321 times bigger than that of Earth. And as for the mass, the sun is more than 99% of the mass of the entire solar system.
  • The moon is a little bigger than 1/4 (27%) of the size of Earth. If it seems very small, you should know that it’s the fifth satellite in the solar system in terms of size. The average radius of the moon is 1,737.5 km. Its diameter is 3,475 km, which is less than 1/3 of the diameter of Earth.
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