What Is An Eclipse? Solar and Lunar Eclipses Explained

  • Aug 01, 2017

Since the beginning of human history, people have looked for the presence of the Sun or moon in the sky. They have acted as the link between cultures and their gods, as well as a working calendar. A few times every year, however, the sun or full moon disappears from the sky during an eclipse. What is an eclipse, and how does it occur?

What is an Eclipse?

An eclipse is when one celestial object moves in front of another one. There are two types of eclipses, solar and lunar.

Solar eclipses

Solar eclipses occur when the moon moves directly between the Earth and Sun.  In this case, the sun appears to totally or partially “disappear” for a period of time.  Solar eclipses, while amazing in that night appears to fall during midday, occur two to three times a year, and can only be seen over a very small portion of the earth.

The last solar eclipse took place on February 27, 2017, and was visible over South America and Africa. The next solar eclipse will occur over the U.S. providing the best view path stretching from Oregon to South Carolina. The town with the best view of the celestial phenomenon is Hopkinsville, Ken. The total solar eclipse will occur on August 21, 2017, at 10:45 AM in Hopkinsville, Ken., and will last approximately 2 minutes. Check out our solar eclipse countdown for more information about solar eclipses.

Lunar eclipses

Lunar eclipses are also rare events, but you can view them at any location with a view of the moon. A lunar eclipse occurs when the moon crosses the earth`s shadow, causing the moon to disappear from the sky.

During a “total” lunar eclipse, the blotted-out moon reappears for a short time, looking reddish-brown. This is because some of the sunlight that reaches Earth is “scattered” back by our atmosphere.  This is the same concept that gives us colorful sunrises and sunsets. A lunar eclipse only happens during a full moon.

In ancient times, people considered eclipses to be a terrible omen, as one of the “heavenly bodies” in the sky was changing colors or disappearing. Early eastern Europeans believed that the red lunar eclipse was the sign of a demon escaping from the moon, and would throw rocks at the moon to stop the demon. Natives in the Americas shared this wonder about lunar eclipses, believing that their moon god was communicating with them during an eclipse.

In reality, lunar eclipses are safe to view and are quite photogenic as well. When the moon is darkened, you can sometimes even see stars that are normally blocked out by moonlight.

The next lunar eclipse is on Monday and Tuesday, August 7 and 8, and will be visible in the entire Eastern Hemisphere – except for where the sky is cloudy, of course.

Lunar Eclipse Science

The Earth`s shadow includes two parts: the penumbra, the outer shell, which blocks some — but not all– of the Sun`s rays, and the umbra, which blocks all direct sun.

When the moon passes through only the penumbra, a relatively unimpressive penumbral eclipse occurs, with little more than a faint “smudge” appearing to darken the moon. When the moon only passes through a part of the umbra, a partial eclipse occurs. Finally, when the Moon passes completely through the umbra, a total eclipse takes place.