Saturday, September 26, 2015

The Magnificent Moon - Part 2

Moonrise, Sunset, and Lunar Eclipses


A spectacular sunset.  We only see this brilliant display when there are clouds!
This month we experience not just a gorgeous supermoon, tomorrow evening (Sunday, September 27th) the Full Moon will also undergo a complete or Total Lunar Eclipse.  What could be more exciting for an astronomy buff!

The sunset this evening was truly glorious...  just enough thin clouds were scattered across the sky to capture and reflect the last red rays of the sun as the Moon rose over the hills behind our home.

The Sun set at 7:01 PM here in Northern California and dusk was gorgeous with red and purple ribbons crisscrossing the sky in the west.

I loved the way the moonlight was reflected on the clouds.
Moonrise this evening was at 6:15 PM, just before sunset and the Moon was well over the horizon and visible over the hills when I first spotted it opposite the sunset.  I took some truly magical photos between 7:15 and 7:30 PM of both the moonrise and this evening's gorgeous sunset.  The Moon will continue to rise in the sky, getting to its peak or passing over the "meridian", shortly after midnight.  It will set in the morning at 7:39 AM.

Early risers can see the nearly full, huge supermoon drift toward the horizon and then hover briefly as it sets in the morning sky shortly after the sun rises at 7:02 AM.

The moon at dusk, shortly after sunset.
The vivid colors of this evening's sunset bode well for tomorrow's weather.  It's an old wives tale and a total fallacy that dust or pollution makes a sunset prettier.  In truth, vivid, colorful sunsets occur when the air to the west is clear and since that air will be over you the following morning, it almost always signals good weather for the following day.

Tomorrow's moon will rise at 6:56 PM, peak and turn full at 7:51 PM where we live on the West Coast and at 10:51 PM on the East Coast.  During this time, we will be privileged to see a total lunar eclipse (see details for viewing below).

On a side note, all full moons bring with them higher than usual tides, but when the Moon is at perigee -- that is, at its closest point to Earth -- the tides are even higher.  This is generally only a problem if it happens coincidentally at a time when a strong end of summer storm brings high winds and high waves.  Then serious beach erosion and damage to critical dunes can occur.  The New England seacoast is no stranger to these problems.

Understanding a Lunar Eclipse  

What makes this month's full moon is that it coincides with a complete or total eclipse that will occur with moonrise on Sunday evening, September 27th.

A lunar eclipse occurs when a full moon is in direct alignment with the Earth and the Sun with the Earth in the center and the Sun and the Moon on opposite sides of the Earth.

Most months, at the time of the full moon, the Moon's orbit is tilted with respect to the Earth and Sun and it passes above or below the point at which the three celestial bodies would be in an essentially straight line.  About every 6 month, conditions may be right for a lunar eclipse but it can only be seen when the full moon rises at or after dark in the part of the world that is viewing the Moon over the horizon.  We are fortunate that that will happen tomorrow night (September 27th) and the eclipse will be visible throughout the entire Western Hemisphere and portions of the eclipse will also be visible in much of Europe and western Africa. 

Where we live in Northern California, the penumbral eclipse will begin before moonrise and we will not see it as the Moon will still be below the horizon. The Moon will rise at 6:56 PM and the eclipse will be almost full at that point.  It will reach maximum fullness at 7:11 PM and the total eclipse will last until 8:23 PM. The partial eclipse (as the Moon passes out of the Earth's dark shadow) will end roughly an hour later (9:27 PM) and the penumbral phase of the eclipse will end at 10:22 PM.

This Infographic, from, shows the positions of the Sun, Earth, and Moon during a total lunar eclipse as well as the distribution of the shadows formed by the Earth as it block's the Sun's rays.  

The shadow cast by the Earth is cone shaped. and when the Moon passes into the Earth's shadow, it passes into the lighter shadow - the penumbra - that extends out from the circumference of the Earth.  

When the Moon moves directly behind the Earth, it is in full shadow, the umbra or darkest part of the shadow.  

After a period of about an hour or so of "totality", where the Moon is in deep shadow behind the Earth, it continues to move through its orbit and once again enters the penumbra. 

During the time that the Moon is in total shadow, it is still visible, but appears vividly colored, often a coppery or red color.  In order to be able to see this phenomenon, you must be on the side of the Earth oriented toward the moon, actually in the umbra, where it will be night time.  If you are geographically on the side of the Earth facing the sun, it will be daytime, the moon will be behind the Earth, and you will be unable to see the eclipse (except on TV or the computer!).

The best place to view the eclipse is where you have a good view of the horizon as the Moon is rising in the East.  The Sun will set in the West at almost the same time that the Moon is rising in the East.  You may be able to see another vivid sunset opposite the spectacular rise of the Moon on the opposite side of the sky.  Followers of the blog can check in here for my own photographs of the Moon throughout the evening.



  1. Cathy, I have always been interested in this stuff. Here the eclipse was to be seen at its best at 3am. Unless I live to be like Methusala (spelling?) I was unlikely to see it again. Well, the sky was clear, went outside with the camera, lo and behold the moon was lying low behind the woodland trees with no access available. Well done on your success, fantastic.


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