moon-horizon-la-gomera-enero-201209

Moon rising over La Gomera, part of the Canary Islands located in the Atlantic Ocean off the coast of Africa. Photo: Roberto Porto

Why the Moon is bigger closer to the horizon

By Kaelan Jungmeyer

We don’t know. Not the writer, but the human population. That is not to say that there aren’t many theories, but we don’t know truly why.

First off, you should probably know that the moon does not get any bigger physically. In fact if you use your camera to take a picture of it when it is high in the sky, then again when it is at the horizon, then you will notice that it is the exact same size! If you look through your legs at the moon at the horizon, everything upside down will make the moon look the same size as when it was in the sky.

One theory is that when the moon is at the horizon, you have a point of reference. The buildings and trees make it seem bigger, while it seems small compared to the entire night sky. A similar thing happens in the ball illusion at the bottom. The center balls are the same size!

Another is that, since things at the horizon are generally farther away, the brain compensates and makes the moon seem larger, even though it is the same size.

Moon Facts 

  • The Earth’s tides are largely caused by the gravitational pull of the Moon.
  • From Earth, we always see the same side of the Moon.
  • The Moon is the only extraterrestrial body that has been visited by humans.
  • The first space craft to send back pictures from the Moon was the Soviet Union’s Luna 3 in October 1959.
  • The Moon is about 1/4 the size of the Earth.
  • It is the fifth largest moon in the Solar System.
  • The average distance from the Moon to the Earth is 238,857 miles.
  • The Moon orbits the Earth every 27.3 days.
  • Mons Huygens is the tallest mountain on the Moon, it is 4,700 metres tall, just over half the height of Mt. Everest (8,848m).

Why does the Moon look different throughout the month?

moon-phases-activity-sheetThe Moon has “phases.” That means it looks a little different to us each night during its one-month orbit of our planet. We describe how the Moon looks with terms such as “Full Moon,” “First Quarter,” and “New Moon” (which we can’t really see, because the side that is lit faces away from us).

The Moon has no light of its own. Moonlight is sunlight bouncing off the Moon’s surface. As the Moon orbits Earth, the Sun lights up whatever side of the Moon is facing it. To the Sun, it’s always a full Moon! If you were looking down upon Earth and its Moon from way out in space over the North Pole, you would see a Moon that looked like one of these:

But we see the Moon from the center of its orbit. So we see different portions of the lit side of the Moon.

Making Oreo Moon phases

This is a simple activity that most any kid, or adult, will enjoy. Open up a pack of Oreo cookies and scrape off (or knowing most people carefully bite off) the creme filling to make the four major phases of the Moon.

Each month, the portion of the Moon we see in the sky changes, passes through phases: growing from New Moon to Crescent to First Quarter to Gibbous to Full, then decreasing until it is back to New Moon once again.

These Oreo “Moons” show how the Moon looks from Earth during these phases as seen in the above illustration.

This article appeared in the January 2013 issue of RocketSTEM.
You may download the entire issue as a PDF file here, or view the magazine online in a full-screen viewer here.