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January 2018’s astronomical event: Lunar Apogee

Dons Manzan & Jam Salazar | Jan. 23, 2017

We have always been familiar with the statement “I love you to the moon and back.” People say it to express the intensity of their feelings for someone they love. What we don’t often realize is that there are moon phases or phenomena that would make the statement less valid, considering the changes in distance between the moon and the Earth.

On January 15, one of these astronomical was witnessed: the Moon Apogee.

The Super Moon and Minimoon

Little is known in understanding our close relationship with our ever-distant lunar satellite, the moon, and what it means to our daily living. Certain beliefs. also associate the phases of the moon to undying facets of old-age traditional practices and superstition. In line with this, we will try to shed some light into some important facts focusing on the apogee and the perigee concept (see Figure 1).

Fig-1. Full moons at apogee (left) and perigee (right) in 2011. Composite image by EarthSky community member C.B. Devgun in India 

Why are there two different episodes and what do these episodes really mean? When the moon is farthest from the Earth, it is called apogee. This means that the moon is seen a bit father as visible to the naked eye. On the other hand, perigee is when its point of orbit is at closes opposition to the surface of the Earth, making it seem a lot bigger to the observer.

According to the National Aeronautics and Space Administration (NASA), our natural satellite is in orbit at an average distance of 234,878 miles (378,000 kilometers) from the surface of our planet (see Figure 2). It has been like this for thousands of years. Little has been known about its orbital parameters aside from being elliptical in orientation, where the moon orbits the Earth at about 1.082 kilometers per second.

Fig-2. The moon’s orbit around Earth isn’t a circle, but it’s very nearly circular, as the above diagram shows. Diagram by Brian Koberlein. Used with permission. Content courtesy: EarthSky.org

Gazing into the heavens

Looking back early on January 2, 2018, a super moon was observed by many across the globe. The Full Moon occurs within 24 hours of the perigee, which is quite visible to the naked eye at the distance of 22,559 miles (356,565 kilometers). This is the closest the moon can get to the Earth this year, according to the Perth Observatory in Western Australia.

Apogee and perigee viewing is best done during a clear night sky, away from the glare and illumination of cities. This is preferably done in rural areas where ambient, natural light enhances vision. The lessened particulates suspended in the air also add to the considerable amount of clarity. It would be quite a joy for those who have a handy pair of night vision binoculars or even a high contrast telescopic lens.