WASHINGTON, June 10, 2015 — Because the moon’s orbit around Earth is elliptical, the distance from the moon to Earth varies from roughly 225,000 miles to 250,000 miles. Earth’s orbit around the sun is also elliptical; its closest approach to the sun, perihelion, is 91.40 million miles. At the most distant point of its orbit, called aphelion, there is roughly 94.51 million miles between Earth and the sun.
The moon is the second brightest object in the sky, reflecting the brighter sun’s light. The biggest impact on our Earth from its greatest “natural satellite” is via gravity, most clearly seen in our oceans’ tides.
Those with closer ties to the Earth cycles will tell you that the moon also affects our crops, our moods and our lives in ways known and unknown.
And yet we spend little time thinking of luna. As the moon spins on its axis, she also orbits around the earth, which means that the view we get of the moon is always the same and the so called “dark side” of the moon is more than a Pink Floyd album; it refers to the fact that one half of the surface of the moon is never visible from Earth.
Look up tonight as the moon sweeps through perigee, its closest approach to Earth for the month. The moon tonight is a waning crescent moon, meaning that it has left its full moon stage on the opposite side of Earth from the sun and is now more than half way to Earth’s day side.
As the moon moves more fully between its two celestial neighbors, it becomes the beautiful crescent of poem and song, until it vanishes completely as a new moon.
While early this morning / late last night (12:44 am to be exact) was the moon’s actual closest approach, its crescent should still be lovely tonight.
At perigee the moon lies 369,711 kilometers (229,728 miles) from Earth. The next perigee moon will be on July 5, 2015.
An interesting bit of lunar trivia is that the moon’s perigees and apogees fall on the same dates over a four-year cycle. They align on the same, or nearly the same, calendar dates every four years, because 53 returns to perigee is nearly commensurate with four calendar years. (information courtesy of EarthSky.org.)
A moon by any other name
Every year the phenomena known as the “supermoon” creates much fanfare and incredible pictures of a moon that seems so close we could reach up and touch the nose on the man who looks down on us.
Classifying a moon either as supermoon or a micro moon is not exactly a science, but TimeAndDate.com uses the following definition:
- If a full moon or new moon is closer than 360,000 kilometers (ca. 223,694 miles) at perigee, it is considered a supermoon.
- If there’s a full moon or new moon when the moon is farther than 400,000 kilometers (248,548 miles) at apogee, it’s considered a Micro Moon.
Our next supermoon is scheduled for Sept. 27, 2015. For celestial observers who wish the catch the Perseid meteor showers, that is great news, as last year’s bright supermoon made the showers difficult to see.
2015 will have six supermoons: the new moons of January, February and March, and the full moons of July 15, Aug. 14 and Sept. 13. The September full moon is the closest supermoon of the year (356,877 kilometers or 221,753 miles from Earth).
There is also the supermoon syzygy or the “perigee-syzygy of the Earth-Moon-Sun system.” In astronomy, the term “syzygy” refers to the straight-line configuration of the three celestial bodies our Earth, the moon and the sun.
Syzygy also happens during a new moon and full moon, and sometimes when the moon is close to the lunar nodes of its path, it causes a total solar eclipse or a total lunar eclipse (courtesy of EarthSky.org)
A total lunar eclipse creates a blood moon, so named for the red hue the moon takes as the Earth’s shadow blocks the sun’s light from reaching the surface and reflecting bright white.