Fall or September Equinox

The September Equinox


This is when the Sun – from our point of view – spends the whole day on the Equator.  Which runs through Ecuador in the Western Hemisphere.  And through Colombia, Brazil.

Globally it runs through these countries and island nations, too:  Sao Tome & Principe, Gabon, Republic of the Congo, Democratic Republic of the Congo, Uganda, Kenya, Somalia, Maldives, Indonesia and Kiribati.

What does this mean?  It means the Sun beats down right over head, at the Zenith at noon, or lunchtime, in these countries.   It means the Sun rises directly in the East and sets directly in the West in these countries.  It means, globally, that at noon local time, the height of the Sun in degrees is equal to this:

Height of Sun in Degrees at ~12:00 on the Equinox = [90 – Latitude of you, the observer]

That is,

Latitude = 90 – Height of Sun in degrees (you can use a protractor) at ~12:00

If you can see the sun through the clouds and rain, why not confirm you are where you think, without use of GPS?

It’s always reassuring when everything seems to adds up  🙂


Screen Shot 2018-09-22 at 6.38.09 AM

So, I will give you a little more insight.  You see which way the Earth rotates? Hold up your RIGHT HAND, like you are going to – almost – make a fist. Stretch out your thumb and rotate your hand a few degrees.  You see?

That is why some of us say the Earth’s Rotation follows the right-hand rule in the Northern Hemisphere.  I like this figure, above, because it forces us to think of the Southern Hemisphere and the Left-hand Rule.

NORTH => RIGHT HAND…

SOUTH => LEFT HAND….

Is that right?  See, I doubt even myself most of the time…

Yep, its right.  Right-Handed in the North…

Most of Humanity is in the Northern Hemisphere, I will be speaking to you most.

“Things” turn out to revolve or rotate according to the Right Hand Rule.  The Earth around its axis; the Earth around the Sun; the Moon around the Earth.  If looked at it from the North or Northern Hemisphere.  Cool, huh?

Is that FIRST QUARTER after FULL MOON, or LAST QUARTER, of the Moon?  Hmmm.   In your mind’s eye see where you are standing on Earth. Hold up a RIGHT-HAND. Rotate it. That is the way the Moon is revolving around the Earth.  Full Moon occurs opposite to the Sun.  Moon on one side of the sky. Sun on the other side, opposite.

Isn’t that, at least, sort of cool?

In the North, this is also how Hurricanes turn.  RIGHT-HAND Rule.  Because Hurricanes have a low-pressure area in the Eye.  They draws their strength from warm water, which then warms the air.  Air goes UP as it is warm. Where your RIGHT-HAND thumb is pointing. UP. See Hurricane IRMA, just below…

Hurricane IRMA

LOW PRESSURE => WARM AIR. UP. RIGHT-HAND THUMB UP.

HIGH PRESSURE must mean COOL AIR. DOWN. RIGHT HAND-THUMB DOWN.

Now we have been armed (or HANDED) to read even those weather charts. Here’s today’s NOAA weather chart of the USA with my RIGHT-HAND in the middle of it…  

Why does IRMA rotate like that?  Because the Earth rotates.  Don’t feel stupid.  No one knew that in 1880!  Seriously.  No one knew that Hurricanes rotated, because of the Earth until 125 years ago!


That is what Prof. Dr. Nansen showed by putting his ship – FRAM – on the Arctic Ice Cap for three years, partly on purpose. The ship moved not only South, but to the RIGHT!  “Was this because of the Earth’s Rotation?”, he ask in his journal.

That is the way the sea current moved.  And the air current, as well.

Here is the Arctic Sea Ice during the year September, 2006 to September, 2007 

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