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# Angular size of the sun and moon

Hi, I am trying to make a simple model of the solar system. I am having trouble setting a scale and I have noticed that the angular size of the sun and the moon seem too small regardless of what scale I use. In the picture I have 3 moons on the left set at 3 different scales. And 3 suns on the right set at the same scales as the moons. The fact that they all appear to have the same angular size means my math is probably right, but leads me to wonder why they appear so small. Even if I could set the scale to 1:1 cm which is obviously impossible, I don’t think it would or should make a difference in their angular size as this is should scale to any scale. I’ve double checked my math on the sphere sizes to distance from camera. It seems I would have to make the sun and moon 3x bigger or 3x closer to to make them look like how they appear from Earth and near earth. Any thoughts?

On earth, the angular size of the sun is 0.5deg. Interestingly, the angular size of the moon is exactly the same.

This does often look ‘too small’, so scaling the sun up to 2deg (4x bigger) can sometimes be desirable, despite being physically inaccurate.

Does it just look too small or is it too small? Any idea how I could calculate the angular size of what I see on the screen?

Keep in mind any shots in movies where the moon looks big is because they used a very narrow FOV.

Thanks, it does look bigger with a more narrow FOV. However, isn’t the human eye about 100 degrees per eye horizontally? As I understand, the maximum angular size the human eye can detect is about .02 degrees which represents a .3 Meter object viewed from 1 km away. In Unreal if I use a 30cm cube (.3m) and set the object 100,000 centimeters away, it is obviously too small to see. If I make the cube 3 meters instead of .3 meters it becomes barley visible at the same distance. Now the moons angular size should be about .52 degrees If I were to make a normal landscape 1 to 1cm scale and add the moon in the scene based on the correct size/distance ratio, it wouldn’t look anything like the moon we see in the sky. I guess I’m just trying to understand if this is a limitation of the distance rendering in Unreal or the resolution or does that moon size actually represent .52 degrees in a 100 degree FOV?

It would if you went into VR. A lot of this is just perception based on seeing things via a monitor.