In the U.S., at 2am on the second Sunday in March we set our
clocks forward one hour for the start of daylight saving time—or to put it
another way, we lose one hour of sleep. This year, the second Sunday falls on
March 8, 2020. And on the first Sunday in November at 2am we reverse that
process by setting our clocks back one hour—we get an additional hour of sleep
to make up for that hour we lost in March. In 2020, that first Sunday is
November 1st.
Standard time—the creation of time zones—was instituted in
the U.S. and Canada by the railroads in 1883. Due to the vast width of the two
countries stretching thousands of miles from the Atlantic Ocean to the Pacific
Ocean, it was necessary to establish some method of standardizing train
schedules. However, it was not established in U.S. law until the Act of March
19, 1918. The Act also established daylight saving time which was repealed in
1919 while standard time in time zones remained the law. Daylight saving time
was re-established in World War II. The Uniform Time Act of 1966 brought
standardization of start and stop dates but allowed for local exemptions from
its observance. Since then, the official beginning and ending dates have
changed several times, the most recent being in 2007. There are many wondering
why we continue to bother with daylight saving vs. standard time as that annual
change seems to have no purpose in today's society. Several states are
currently considering doing away with it.
Those states that have previously opted for the exemption
from daylight saving time are Arizona (except for the Navajo, who do observe
daylight saving time on tribal lands), Hawaii, and the overseas territories of
American Samoa, Guam, the Northern Mariana Islands, Puerto Rico, and the United
States Virgin Islands.
There are several states that are split between two time
zones. Oregon and Idaho are split between the Mountain and Pacific time zones.
Florida, Michigan, Indiana (I think I read somewhere that one of Indiana's time
zones observes daylight saving time and the other time zone does not),
Kentucky, and Tennessee are split between Eastern and Central time zones.
Nebraska, Kansas, Texas, North and South Dakota are divided between Central and
Mountain time zones.
At one time, Alaska covered four time zones. That has been
changed and Alaska is now in two time zones. More than 98 percent of the
state's population are in one of these zones, now called Yukon time, which is
one hour earlier than Pacific standard time and four hours earlier than Eastern
standard time.
And then there is the other annual observance, the one
dictated by science/nature—the vernal equinox.
Equinox translates literally to "equal night."
This year, on Thursday, March 19, 2020, at precisely 11:50pm
eastern daylight time, the sun crosses directly over the Earth's equator. The
fact that it's night time in the U.S. and Canada does not change anything. That
moment is known as the vernal equinox in the Northern Hemisphere announcing the
arrival of spring and the autumnal equinox in the Southern Hemisphere
announcing the arrival of fall. A second equinox will occur in September.
According to the Farmer's Almanac, this is the earliest first day of spring in
the last 124 years.
The fact that the Earth has distinctive seasons is due to
the 23.4 degree tilt of the Earth's axis. The Earth receives more sunlight
(longer daylight hours) in the summer and less sunlight (fewer daylight hours)
in the winter. The tilt of the axis
makes the seasons opposite in the Northern and Southern Hemisphere. At the
north pole summer gives six months of daylight while at the same time the south
pole is experiencing six months of darkness. The closer you are to the equator,
the number of hours of daylight and darkness become more equal.
The fall and spring equinoxes are the only two times during
the year when the sun rises due east and sets due west. Modern astronomy aside,
people have recognized the astronomical connection to the season changes for
thousands of years. The ancients of various civilizations all over the world
built structures that illustrate this—temples dedicated to their various gods
that modern man recognizes as observatories. Not only the spring and fall
equinox days, but also the summer and winter solstice days (most and least
daily hours of sunlight).
I think it's also interesting to note a connection between
the spring equinox and Groundhog Day (another holiday derived from the
practices and celebrations of the ancients). If the groundhog sees his shadow
on February 2, we have six more weeks of winter. And by "coincidence"
that six weeks takes us to the spring equinox.
A little bit of equinox trivia: According to folklore, you
can stand a raw egg on its end on the equinox. One spring, a few minutes before
the vernal equinox, twenty-four almanac editors tested the theory. For a full
work day, seventeen out of twenty-four eggs stood up on the large end. Then
three days following the equinox, they tried the same test again. And guess
what? The results were similar. Perhaps
the second test was still too close to the equinox? :)
And there you have it—your science lesson for the day.