6degrees AstroBlog

Full Moon Fever

By Dr. Irwin Horowitz, 8-27-07

	(c) 2007 Irwin Horowitz

I want to remind my regular readers that there will be a total lunar eclipse visible tomorrow morning.  The initial partial eclipse phase will begin just before 3 a.m. MDT (2 a.m. PDT), with totality commencing about one hour later.  The total phase will last about 90 minutes, ending shortly before 5:30 a.m. MDT (4:30 a.m. PDT).  The final partial phase will end about one hour later.  The Moon should be visible for at least part of this time across the entire intermountain west, low in the south or southwestern sky.

A lunar eclipse occurs when the Moon passes through the Earth’s shadow.  This can only occur at full moon, when the Earth is located between the Sun and the Moon.  It doesn’t occur every month because most of the time, the Moon passes either above or below this shadow.  However, about twice each year, it will pass either partially or fully through the shadow, producing a lunar eclipse.  The last one occurred on 03 Mar of this year and the next one will be 20 Feb 2008.  That one will be visible in the early evening hours here, as the full moon rises in the east.  While it will be more accessible here in terms of the time of day, the weather in February is more problematic for ensuring good viewing.

During the event, some of the things to take note of are the color and brightness of the eclipsed moon.  It should take on a reddish hue due to the refraction of sunlight through the Earth’s atmosphere.  Occasionally, when the atmosphere contains plenty of dust and other particulates due to volcanic activity, the eclipsed moon will take on a darker appearance compared to how it looks when the atmosphere is relatively clear of soot.

As you are watching, close your eyes and imagine the tremendous shadow cone extending outwards in space from the Earth out beyond the Moon.  Visualize the Moon, as it is orbiting around our planet, passing through this shadow cone.  It progresses deeper and deeper into the darkest part of the shadow until mid-eclipse, and then exits from behind in the reverse order until it is once again fully illuminated by our Sun.

Consider what this must look like if you were on the surface of the Moon.  Looking back towards the Earth, you see it swallow up the distant Sun, until it completely blocks it off.  All you see then is a ring of red-hued light circling our home world.  Think about this light passing through the egg-shell thin blanket of our atmosphere and recognize that layer is all that separates us from the vacuum of space.

If you are an early riser, to go to work or just in general, or you like to go to bed really late, I would encourage you to take the opportunity to look up at the moon during the eclipse.  It really is visually enthralling.  Use the comment section here to let everyone know about your observations and experiences observing the eclipse.

During the eclipse, if you are able to view the eastern sky, you should take note of the planet Mars, which is presently located in Taurus the Bull to the left and slightly above the orange colored star Aldebaran.  Note the hue of the planet in comparison to the star.  The reason Mars takes on this color is the present of iron oxide, or rust, in its soil.  Aldebaran has this color because the temperature of its photosphere is about 3000 K.

UPDATE: I’ve posted one of the photos I took this morning of the eclipse to this article.

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