By David Ward
Sky watchers will be treated to another lunar eclipse at the end of September. The best thing about this one is that you will not have to get up in the middle of the night to see it. For us here in western North America, the full moon will rise in the east at sunset already partially eclipsed. The date to mark on your calendar is Sunday, Sept. 27. Find yourself a spot with a clear view low into the east and enjoy the show.
September’s eclipse is the fourth and final one of four, six months apart, which began in April 2014. A series of eclipses like this is known as a tetrad.
As a bonus, the eclipsed moon will also be a super moon, which occurs when a full moon is closest to Earth in the moon’s slightly elliptical orbit around us. At this time the moon will appear a little bit larger than normal.
For the past few years the media have made a lot of noise about super moons. When I first started getting into astronomy as a kid, we never heard of such a thing. Quite frankly unless you spend quite a bit of time moon gazing, you probably will not notice the moon looking any bigger. It will look larger just when it is rising because we are seeing it through a lot of atmosphere, much more than when it is higher in the sky. Our atmosphere acts like a lens, enlarging the moon when it is low.
Shortly after the moon rises it will completely enter Earth’s shadow. That is what an eclipse of the moon is all about, our great big shadow extending out into space blocking the sun’s light on the moon. Watch for a striking reddish or even coppery color enhancing the darkened moon. This phenomenon is caused by light from the sun bleeding through our atmosphere and illuminating the lunar surface.
Lunar eclipses nowadays are often referred to as “blood moons.” The term has no scientific significance but has recently become popular in the media. There is an obscure biblical reference to blood moons as a sign that the end of the world is near. Some Bible scholars believe that four eclipses in a row signifies that our time is nearing its end on Earth. So be sure to watch this eclipse, it may be the last one we will ever see!
The planet show that we enjoyed for months in the evenings has now moved to the early morning sky. Look for super-bright Venus, kind-of-bright Jupiter and dimmer Mars in the east before sunrise. Saturn can still be seen in the evening. Look for it shining with a steady yellowish light low in the southwest. The twinkling reddish star to its lower left is Antares, the heart of the Scorpion.
On Sept. 23, Earth reaches that point in its orbit known as the autumnal equinox. When the apparent path of the sun crosses an imaginary line in the sky known as the celestial equator, then the season of autumn begins.
I know that it all sounds a bit hazy, but on this day the tilt of the Earth is exactly perpendicular to the orbit of the Earth and the days and nights are of almost equal length. It also means we are halfway back to winter from the height of summer, which, after all we have been through this summer, may not be such a bad thing.