This year’s Supermoon will be tomorrow night, Saturday May 5, 2012.
Supermoons are full moons (or new moons) which occur at the perigee (nearest point) of the moon’s orbit around the earth. On average, a supermoon occurs about once a year. The last one was March 19, 2011.
Full moons appear to vary in size due to the oval orbit of the moon. The moon follows an elliptical path around Earth with one side (perigee) closer than the other (apogee). The closer a full moon is to the earth in its orbit, the larger it looks. Perigee full moons (supermoons) look extra large and bright.
The moon will reach perigee at 11:34 pm EDT on May 5, 2012. One minute later at 11:35 pm it will become “full”, lining up with the sun and earth. Last year’s supermoon was about 250 miles closer than tomorrow night’s supermoon, because there was not a full minute lag last year between the perigee and the sun-earth-moon alignment.
At perigee, the moon is about 30,000 miles closer to the earth than at its apogee (farthest point), and it’s about 30% brighter and looks 14% larger. But it’s still about 220,000 miles away from earth.
The gravitational attraction of the moon on the earth is inversely proportional to the square of the distance between them. Thus as the distance decreases the gravitational force increases by the square (at half the distance, it’s 4 times as great).
Calculating using the inverse square law shows that the moon’s attractive force on the earth is about 30% stronger at perigee than at apogee. This significant increase (30%) in the moon’s pull on the earth affects tides and possibly helps generate earthquakes.
(The calculation is (250,000/220,000)**2 = 1.29, so 29% greater attractive force of the moon on the earth at perigee.)
See this article on Earthquake Risks for more information on the influence of the moon on earthquakes.
Some think that a very unusual supermoon may have contributed to the sinking of the Titanic on her maiden voyage 100 years ago on April 15, 1912. The luxury passenger liner was the world’s largest ship and sank two and a half hours after hitting an iceberg in the north Atlantic. Of the 2,224 on board, 1,514 died.
Astronomers from Texas State University say the most extreme supermoon in 1400 years was on January 4, 1912. This supermoon occurred at the same time as the earth’s perihelion (closest point to the sun in its orbit). The combined gravitational effect of the sun and moon on the ocean tides may have disgorged more artic icebergs into the Atlantic than usual.
We know the Atlantic was unusually full of icebergs that winter. In fact, the nearby SS Californian had warned the Titanic by radio of heavy pack ice. The Californian stopped for the night because of the icebergs, but the Titanic forged ahead. The combination of a very strong supermoon and the earth’s perihelion may have caused more icebergs, and weather conditions influenced their location in the shipping lanes.
Here’s a 3:25 video from NASA about supermoons.
Soli Deo Gloria.
©William T. Pelletier, Ph.D.
“contending earnestly for the faith” (Jude 1:3)
Friday May 4, 2012 A.D.
Read my April 2012 newspaper column:
Operation Geronimo and the Resurrection
Then God said, “Let there be lights in the expanse of the heavens to separate the day from the night, and let them be for signs, and for seasons, and for days and years; and let them be for lights in the expanse of the heavens to give light on the earth”; and it was so. And God made the two great lights, the greater light to govern the day, and the lesser light to govern the night; He made the stars also. And God placed them in the expanse of the heavens to give light on the earth, and to govern the day and the night, and to separate the light from the darkness; and God saw that it was good. And there was evening and there was morning, a fourth day. (Genesis 1:14-19)