The July supermoon is the first of a spectacular summer. Already being dubbed the summer of super moons, the 2014 night sky is set to provide a great show for those who look up. A supermoon may appear to be 14 percent larger and 30 percent brighter than an average full moon.
Each month of this summer the full moon will coincide with perigee – the moon’s closest point to earth in its orbit. Like all celestial bodies, the moon’s orbit is an ellipse with the earth as one of its foci. Therefore, the distance between the moon and earth changes throughout the month. One revolution of the moon takes 27.3 days; but the earth is also spinning, so the moon cycle occurs every 30 days. Because of this discrepancy, the full moon, when the moon is on the opposite side of the earth from the sun, can occur at any time along its elliptical path. On a side note, there really is a dark side of the moon – meaning that people never see it from earth. The moon’s revolution and rotation are exactly the same length so the moon always shows the same face. No matter when someone looks up at the moon, he or she sees the man in the moon looking back at him or her.
The moon appears largest as it rises and sets because people see it in relation to the horizon. Viewers are awed by the size and color of the full moon when it first appears in the sky. A full moon always rises at approximately 6:00 p.m. and sets at 6:00 a.m. This could be a problem for summer supermoons because the sun is still shining. Happily, the varying size of the moon is only an illusion. The moon does not change diameter as it travels across the night sky. The brain changes the way the moon is perceived by the eye. When at the horizon, the brain assumes the moon is far away and therefore is larger than observed. When high overhead in an empty sky, the brain ascertains that the moon is closer and makes observers believe it is smaller. It is hard to overcome the brain’s trend towards shape consistency, but stargazers can be assured that the moon at midnight is just as magnificent as the moon in the evening.
The July supermoon is the first of a spectacular summer. The full moon should appear equally round and large on both Friday, July 11 and Saturday, July 12. Then again on Aug. 10 and Sept. 9 the full moon will coincide with perigee. In fact, the supermoon of Aug. 10 will occur in the same hour as perigee so it will appear to be the grandest supermoon. Many astronomy enthusiasts feel it is fun to look forward to viewing these moons and to spend time gazing at the night sky, but the supermoon spectacle is also caused by an illusion.
The moon does not actually change size. Objects that are closer to an observer appear larger, so the supermoon is a bit of a misnomer; it is the same moon but it is simply 50,000 miles closer to the earth. A prime example of this phenomenon is the relationship between the moon and the sun. The two spheres appear to be the same size in the sky. In fact, both lunar and solar eclipses are possible only because the sun and moon create the impression of being the same size. The sun is 400 times larger than the moon, but also 400 times farther away from Earth. The size difference is mitigated by the difference in distance.
Ironically, it is the illusion of the supermoon and not necessarily observable characteristics that will have people looking up in awe this summer. Most of them will not be able to discern the differences, but the idea of a fabulous display will have them taking note of the full moon. Moon gazing, while not having mystical properties, is always an inspiring pastime. The moon fascinates because it is the clearest evidence of existence beyond the earth. It abides within the gravitational pull of the earth while remaining separate. It reflects the intense light of the sun with a gentle glow. Its craters and basalt plains have remained unchanged for billions of years. Regardless of the reason, though, the supermoons of 2014 should be a splendid sight. The July supermoon is the first of a spectacular summer. Many people are looking forward to enjoying the summer-long show.
By: Rebecca Savastio