MOONLIGHT IN VERMONT...AND ELSEWHERE

Anticipating a major celestial event a little more than a month from now, I think it might be helpful to consider over the next weeks some facts about the three participants:  Sun, Moon, and Earth.  Let’s start with the Moon, excluding facts you probably already know:

• The moon takes its name from the Anglo-Saxon word moneth, also, of course, referring to the 28 day period between successive new moons. In fact, the time between two new moons varies somewhat because the location of the new moon with respect to the earth and the sun changes as the earth moves around the sun.  The position of the moon is also slightly affected by gravitational influences from other planets (and like everthing else, by everything else in the universe).
• There are about 12.5 new moons a year, but only 12 months, and as a result the moon’s time table does not match the sun’s. This, and the time variantions between new moons were excruciating problems for early astonomers who sought to show that the universe is entirely earth centered and orderly.
• The diameter of the moon is about 25% of the diameter of the earth, but its mass is only a little more than one percent of the earth’s.
• From earth we can see only 59% of the surface of the moon, as the moon rotates on its axis in the same amount of time it takes to circle the earth, but with a little wobble thrown in.
• Total lunar eclipses (when the earth casts a shadow on the moon) are visible anywhere on the earth where it is night at the time of the eclipse. Including partial eclipses, eclipses of the moon can last several hours. Lunar eclipses are far more frequent than total solar eclipses (when the moon gets between the earth and the sun) which are visible much less frequently, only in narrow bands on the earth’s surface, and then only briefly. 

More next time. 

Yours from the field,
Andy