Sunday September 27: Rare Supermoon Lunar Eclipse and the Sky Cover Forecast

On the evening of Sunday September 27th (mainly between 7 and 8:30 pm), we will be able to view an astronomical treat that hasn't happened in over 30 years! There will be a combination of a supermoon (perigree full moon) along with a total lunar eclipse! So what exactly is a supermoon? It's a new or full moon closely occurring with perigree - the moon's closest point to Earth in its orbit. This particular supermoon will be the closest supermoon of the year (other full moon supermoons this year: August 29th and October 27th) being only 221,754 miles away from Earth.
About three or four times a year (in the spring and the fall), the new or full moon coincides closely in time with the perigree of the moon - the point when the moon is closest to the Earth. Image Courtesy NOAA
Like I mentioned earlier, this September supermoon will be a treat because it will coincide with a total lunar eclipse! Check out this great animated video by NASA's Goddard Space Flight Center explaining the Supermoon Lunar Eclipse and its rarity. On the night of September 27th, 2015 this supermoon lunar eclipse will be viewable in the night sky for those living in North and South America. Those living in Europe and Asia can view it in the early morning hours of September 28th. The total eclipse will last one hour and 12 minutes. Earth's shadow will begin to dim the supermoon slightly beginning at 5:11 pm PDT. A noticeable shadow will begin to fall on the moon at 6:07 pm, and the total eclipse will start around 7:11 pm. Good thing that sunset will be around 6:48 pm here in Reno, so as the moon rises in the eastern sky the eclipse will already be in progress! NASA's Scientific Visualization Studio has a great website that will continue to update as September 27th-28th approaches. The next lunar eclipse that coincides with a supermoon won't occur until 2033 (and the next lunar eclipse viewable from the western U.S. won't occur until January 2018), so be sure to check this one out!


The Moon moves right to left, passing through the penumbra and umbra. Courtesy of NASA Scientific Visualization Studio 
Now that we have all the astronomical formalities out of the way, we will move on to an important aspect of this event...the meteorology! No, not meteors obviously. We are switching gears and need to see if clouds are going to limit the viewing of this rare event. 

 The main concern for viewing will be the presence and thickness of cirrus clouds Sunday evening. Unfortunately, the latest forecast models are indicating a large area of cirrus clouds spreading across eastern California and western Nevada, due to southwest flow aloft ahead of a low pressure in the eastern Pacific. While this cloud cover could affect the viewing, all is not lost as the cirrus may be thin enough at times to allow for the eclipse to be visible. The presence of some thinner cirrus may even produce a more dramatic view (or photo) of this eclipse. At this time, there does not appear to be any specific nearby location where less cloud cover is expected, so planning a long drive to chase more favorable conditions is not recommended. 

 The good news is that unlike a solar eclipse where the totality stage typically only lasts a few minutes, Sunday's event will last over an hour so there will be more opportunities to view at least a portion of this eclipse, even if some cloud cover is present. The evening timing is also more convenient for most people to make plans, without interrupting typical sleep time.   

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