A lunar eclipse is a celestial event that occurs when the Earth blocks all or part of the sun’s rays, preventing them from reaching the moon and thus creating a shadow across the moon. A lunar eclipse can happen between two and four times per year. There are three types of lunar eclipses, two of which are visible to anyone on the nighttime side of the Earth when the eclipse occurs.
The moon orbits the Earth every 29.5 days. The circling of the moon around the Earth causes the phases of the moon. The phases of the moon are: New, New Crescent, First Quarter, Waxing Gibbous, Full, Waning Gibbous, Last Quarter, and Old Crescent. With the exception of the New Moon, the various phases of the moon are visible and easily identified. For a lunar eclipse to occur, the moon must be in the Full phase and pass through some portion of the Earth’s shadow.
Depending on the location and alignment of the sun, the Earth, and the moon, one of three types of eclipses can occur. A Penumbral Lunar Eclipse occurs when the moon passes through Earth’s penumbral shadow. This lunar eclipse is only visible with the aid of high-powered, astronomical viewing devices. Most standard telescopes are not optically strong enough to allow a viewer to see a penumbral eclipse and so they are of very little interest to people outside of the field of astronomy.
A Partial Lunar Eclipse occurs when a portion of the moon passes through the Earth’s umbra and a portion of the moon is shadowed from the sun. A partial lunar eclipse is visible, even to the naked eye. The final type of lunar eclipse is the Full Lunar Eclipse and occurs when the entire moon passes through the Earth’s umbra, creating a complete shadow across the moon. A full eclipse, witnessed under the ideal circumstances, such as clear skies, late at night or very early in the morning, can be the most spectacular lunar eclipse to see.
Contrary to a solar eclipse, which requires protective eye gear to witness safely, a lunar eclipse requires no special viewing instrumentation. Most meteorologists are well aware of a lunar eclipse in advance and typically broadcast the date and approximate ideal viewing times. Depending on the refraction of the sun’s rays from the Earth’s atmosphere, a lunar eclipse will cause the moon to cast off a dark brownish, blood red, or burnt orange hue. The best places to view a partial or total lunar eclipse are those located farthest away from large cities with lights.