What Causes the Moon to Come Up Real Yellow?

What the Moon Really Looks Like

• The surface of the moon is made of gray dust and rock. There are darker patches called lunar maria. The maria were caused by the eruption of volcanoes on the moon billions of years ago. In addition to the gray rock, some rare green rocks called olivine can be found. Scientists believe the olivine likely came from the molten mantle of the moon during the moon's formation. It is found mostly at the edge of craters on the moon.

Particles in the Atmosphere

• Many of the apparent changes in the moon's color are caused by the number and size of particles in the Earth's atmosphere. Pollution, smoke and dust change the appearance of the moon. Moisture in the air, in the form of humidity or clouds, can also change the way that light is scattered. When soot or ash is in the atmosphere due to a large fire or volcanic eruption, the moon can even appear blue or purple.

Time of Day

• When seen during the day, the moon looks white because of the contrast with sunlight and blue sky. As the moon begins to rise in a dark sky, it looks more yellow or orange because we are seeing it through a thicker layer of atmosphere, which scatters the light at the blue end of the spectrum and leaves the yellow and red light to reach us on earth. The higher the moon goes in the sky, the whiter it looks.

Eclipses

• A lunar eclipse can cause some of the most dramatic changes in the moon's appearance. As the Earth moves between the sun and the moon, blocking the moon's light source, it appears yellow, orange, red or even brown. This is because it is in the Earth's shadow, and the only light reaching it is filtered through our planet's atmosphere. As on a typical night, the color of an eclipse can be affected by the type and size of particles in the atmosphere.