A lot of the joy that comes from night sky doesn't involve just looking at it; it's about experiencing the incredible things the sky has inspired in human beings throughout the ages. For instance, this week brings the first New Moon of the Spring, which is a phase we can't see, but it’s a nice set up for some marvelous astronomical history.
The New Moon on Thursday, April 7, will be the closest New Moon of the year. The technical term for this is 'perigee moon', and this is the kind of Moon that causes higher tides than normal.
But to understand what 'perigee moon' means, you have to know that the Moon doesn't just orbit the Earth in a circle, it follows an elliptical path, which is like a flattened circle. This is the same kind of path that the Earth and planets follow around the Sun.
So this means that there are times every month when the Moon is closer to the Earth, and times when it is farther away. And sometimes, the close approach, or perigee, coincides with the Moon's New Phase, like this week.
But do you know who figured out that the Moon has an elliptical orbit? It was Johannes Kepler, a German mathematician and astronomer living in the 16th century.
Kepler lived several generations after Copernicus suggested the Earth was in motion around the Sun, but this idea was still not universally accepted. Even more than that, in Kepler’s era there was no real distinction between astronomy and astrology. The division was actually between astronomy, a branch of mathematics, and physics, a branch of natural philosophy, which is why he declared he could: demonstrate by means of philosophy that the earth is round, and is inhabited on all sides; that it is insignificantly small, and is borne through the stars.
Think of Kepler as you watch the Moon for the next two weeks, because from closest New Moon on the 7th, it will speed away from Earth on its elliptical orbit and arrive at Full Phase on April 22nd as far away from us as it can get!