Wednesday, March 18, 2015

MWN Lightning Round: A trio of astronomical events on Friday!

The MWN Lightning Round returns! This Friday, March 20, will feature not one... not two... but THREE astronomical events!

Vernal Equinox - SPRING!

The official first day of spring is Friday, March 20. Specifically in Memphis, the equinox occurs at 5:45pm CDT, when the sun crosses the equator from south to north. For the next 6 months, the sun will remain north of the equator, resulting in the usual hot, sultry summer in the Mid-South!

The orientation of the sun to the earth on the vernal equinox

In an odd technicality, while equinox means "equal parts day and night," the length of the day in most places is not actually a precise 12 hours on March 20. In Memphis, our 12-hour day was on March 17, when the sun rose and set at 7:09 (am and pm respectively). The reason for this is because the earth's atmosphere refracts, or bends,  sunlight, such that we can actually see the sun rising (and setting) a little before (after) it technically occurs. For more details, we invite you to check out this article from

The Missing Supermoon

A supermoon occurs on Friday! But don't get too excited... A supermoon, or perigee moon, occurs when a full or new moon makes its closest approach to Earth, thus making it look larger than usual. By a looser definition, it occurs "with the moon at or near (within 90% of) its closest approach to Earth in a given orbit." By this definition, there are 6 supermoons in 2015. However, this month's supermoon, which also coincides with the equinox and an eclipse (see below) is a NEW moon, meaning it is 100% obscured by the Earth's shadow. Thus, the "missing supermoon!"

Total (solar) eclipse of the heart

The third in our astronomical trilogy will require an expensive plane ticket to be able to see in person, as it won't be visible in the Americas either. (Basically, we realized we're telling you about a bunch of stuff you won't be able to experience firsthand...) A total solar eclipse will occur in the wee hours of the morning Friday with best viewing over northern Europe and into Greenland.

A solar eclipse occurs when the Earth, moon, and sun all line up in such a way that the moon blocks the sun for viewers on Earth, either partially or totally (thus the type of eclipse). The next eclipses visible in Memphis will be a partial lunar eclipse in the early morning hours on April 4 and a total lunar eclipse on September 27. The next solar eclipse viewable locally occurs August 21, 2017 - a near total eclipse! (We'll be sure to remind you...)

Cool astronomy stuff like these events (at least the supermoon and eclipses) can be watched live, or later, on the internet if you can't shuck out the cash to fly to where they are visible. There are several good sites, but we especially like

So there you are - 3 astronomical events all occurring on the same day!

Erik Proseus
MWN Meteorologist

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