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Big Moon on the Horizon

We’ve all noticed that the Moon looks like a big Moon when it is low in the galactic horizon. And no, I’m not talking about the band, Big Moon, I’m talking about that large celestial body that orbits closely around our planet. A great place to observe this big Moon is the Twilight Room or the Rooftop Garden at the Moonrise hotel. Most people think that the big Moon is just closer to Earth. Well, most people are wrong in this case.

Is it a big moon because of the orbit?

The Moon’s orbit around the Earth is elliptical, meaning that it is a circle, not an oval. This orbit does not change enough in one night to explain why the Moon can look twice as big the same night. So if the Moon’s orbit is not the reason, what is going on?

Do scientists know why it’s a big moon?

Here’s the thing that might shock you, scientists aren’t exactly sure why it looks so big! We do know that it usually only looks big when it is low on the horizon. We also know that ancient scientists such as Ptolemy even tried to figure this issue out. Scientists do have some neat hypothesis of what is going on.

The “apparent distance” hypothesis

One hypothesis is called the “apparent distance” hypothesis. This hypothesis is that our mind perceives objects in the horizon farther away; therefore, when the Moon is on the horizon, it tries to compensate for the perceived perspective change and makes it look bigger. But this theory does not hold up in that most people perceive the horizon moon as both bigger and closer than when it is high in the sky, not farther away.

The “relative size” hypothesis

A more popular hypothesis is called the “relative size” hypothesis. This hypothesis states that we perceive size not solely by the retina, but also by what is around the object we observe. When nothing is near the Moon, and it is by itself high in the sky, we perceive it as smaller. When it is near other smaller objects like trees on the horizon, our mind automatically thinks the Moon is more prominent in this case. 

The big moon mystery

Scientists still aren’t sure exactly which hypothesis is correct on why the Moon looks bigger sometimes. They do know that it is not actually any closer and that it is most likely some trick in our mind’s perception of it. It might be shocking to you that we don’t know the exact answer yet, but it is also reassuring that there are still some moon mysteries unsolved.

Maybe you can solve this mystery yourself! See the big Moon by staying at the Moonrise Hotel.