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The first full moon of this spring season came early enough after the March 2016 equinox to allow for a fourth full moon to take place just prior to the summer solstice.
We had the equinox on March 20 and full moons on March 23, April 22, May 21 and now on June 20 at 11:02 Universal Time. The summer solstice will follow at 23:34 Universal Time. (That is 7:30 pm EDT – use the worldtimeserver.com to convert time zones.)
Last year, we had a father’s day solstice that got me thinking about childhood summer and father memories. Thinking about summer and full moons, sends my thoughts to nights on the beach when the full moon over the ocean looks bigger and more dramatic and gives a soft light to the beach.
As we slide into summer in the Northern Hemisphere, the solstice (from the Latin solstitium, from sol-sun) and stitium- to stop), it’s a good day to stop ourselves and consider the season past and one ahead.
We now know that the Sun does not stop on the two solstices but simply crosses a path and “shifts” position at a moment in time. Do you observe the position of the Sun during the year? You probably don’t in as careful a way as I do or astronomers, but perhaps you notice that the Sun is higher in the sky throughout the day now. Have you ever noticed in the morning that the sun rises in relation to your home and your windows from different places in winter and summer? From my usual morning coffee spot in the family room, the Sun is shining right on me in winter, but come summer it’s streaming in a window on the other side of the room.
On the summer solstice tomorrow, the Sun is directly overhead at its most northern point at “high-noon.” There will be more sunlight in the Northern Hemisphere on this day than any other – even if it is cloudy or raining in your little corner of the world.
Why isn’t this also the hottest time of year? The atmosphere, land, and oceans are still cool from winter and spring and absorbing part of the incoming heat and energy from the Sun. But as the land and, especially, the oceans release that stored heat later in the summer, that will bring us our hottest days and nights.
Back in early June, I wrote about looking westward in evening twilight and easily spotting the planet Venus as the brightest “star.” That third-brightest object in all the heavens (after the sun and moon) was accompanied then by an also bright Jupiter.
From then on, Venus slowly began to sink toward the sunset. Like the arrival of the Perseid meteor shower, this movement is surer than the seasons in nature. Sometimes summer stays longer than the calendar tells it to stay and winter comes earlier or later. But today, 10 weeks later, Venus will set with the sun and make its transition out of the evening sky and into the morning sky.
The celestial clock clicks forward, unconcerned with us and our little lives.
I have always had a sundial in my garden. It keeps you in touch with the movement of the Sun during the day and during the seasons.
My basic horizontal sundial shows a shadow from its style onto a surface marked with lines indicating the hours of the day. The style is the time-telling edge of the gnomon, the straight edge. As the sun moves across the sky, the shadow-edge aligns with hour-lines.
Sundials that directly measure the sun’s hour/angle must have that edge parallel to the axis of the Earth’s rotation to tell the correct time throughout the year. The style’s angle from the horizontal should equal the sundial’s geographical latitude, but in most inexpensive sundials the hour angles are off and cannot be adjusted. There are many other types of sundials.
Isaac Newton developed a convenient and inexpensive reflection sundial using a small mirror placed on the sill of a south-facing window. The mirror casts a single spot of light on the ceiling and, depending on the geographical latitude and time of year, the light-spot on the ceiling was drawn large enough to be accurate.
Most mass-produced sundials are not the most accurate timekeepers, but in mid-April time by the sun and time by my clocks agrees. Noon is noon in both places.
I adjust my sundial as the months move past me, but I suppose that is a bit of a cheat. This weekend the length of the day as measured by the midday sun is slightly less than 24 hours long. This discrepancy between my watch and the Sun accumulates until mid-May when noon on my sundial will be a few minutes earlier than the clock. After that the sundial middays will become slightly more than 24 hours long and by mid-June, they will match up again.
Cycles. Very much a part of our lives, whether we pass attention to them or not.
I have been writing about the changing of the seasons for a few years now and there is only so much you can say about the spring equinox, autumn equinox and the solstices of summer and winter. I try to find a new path into them and for this season I am thinking about spring in music and in the sky.
As a quick review, “equinox” is derived from the Latin aequus (equal) and nox (night), because the night and day are approximately equal in length on that day. We experience an equinox in spring and fall when the tilt of the Earth’s axis is inclined neither away from nor towards the Sun which is vertically above a point on the Equator. An equinox actually occurs at a specific moment in time (for 2015, today, March 20 at 6:45 pm EDT), but commonly people refer to the entire day as the equinox or first day of the season.
It is very “northern” of me to say it is the Spring Equinox, because in the Southern Hemisphere this celestial observation means the start of autumn. Being that autumn is my favorite season, I have often thought that I should travel between the two hemispheres to get two autumns each year. Unfortunately, the Sun doesn’t allow me to live in a three-season world and avoid winter.
(Soundtrack to this post)
The Four Seasons (Italian: Le quattro stagioni) is a set of four violin concertos by Antonio Vivaldi (1720) and his best-known work. My knowledge of classical music is shallow, but I was reading about this piece and discovered a few interesting nuggets.
I like that Vivaldi provided some additional instructions with the music, such as “The barking dog” in the second movement of “Spring.”
It seems that there is some debate as to whether or not the concertos were written to accompany four poems (sonnets) or if the sonnets were written to accompany the music. It doesn’t seem to be known who wrote these sonnets,and some say that Vivaldi wrote them himself. Either by plan or coincidence, each sonnet is broken down into three sections, nicely corresponding to a movement in the concerto.
The Four Seasons is sometimes classified as “program music,” instrumental music that intends to evoke something extra-musical. For me, the four pieces, especially “Spring,” does evoke the season.
If you listen to the music tonight, I suggest that you turn your eyes to the sky and look for Arcturus. It is one of the brightest stars. Due to its northerly location on the sky’s dome, it is visible for much of the year in the Northern Hemisphere and its appearance in the evening sky heralds the coming of the spring equinox.
Like other stars, Arcturus rises four minutes earlier every day and now Arcturus will appear at dusk (instead of nightfall or early evening) which is its signal of spring in our hemisphere.
Arcturus is the brightest star in the constellation Boötes the Herdsman. It is not one of the best-known constellations. The name comes from the Greek Βοώτης, meaning herdsman or plowman (literally an ox-driver; from boos, related to the Latin bovis, “cow”). It is one of the 48 constellations described by the 2nd century astronomer Ptolemy, but it was first used by Homer in his Odyssey as a celestial reference point for navigation.
Homer described it as “late-setting” or “slow to set.” It is not clear exactly whom Boötes is supposed to represent in Greek mythology is not clear. The story I will go with is that he was a son of Demeter, twin brother of Plutus, a ploughman who drove the oxen in the constellation Ursa Major. The ancient Greeks saw what we call the “Big Dipper” as a cart with oxen.
It seems a nice match with the spring that one myth associated with Boötes is that he invented the plow which certainly is associated with spring and planting. If you think of him as a “herdsman,” that works too, as those who watch over a herd of cows, sheep or other animals leads a nomadic life very much guided by the seasons. Spring is the time to move to those areas that were snow-covered and the tain and melting turns the land green again.
If staring up at the big sky makes you feel small and timeless – a good feeling, I believe – then also consider this: even the equinoxes are constantly changing. They are not fixed points but move westward along the ecliptic, passing through all the constellations of the zodiac in a period of 26,000 years. This motion is called the precession of the equinoxes. And we think that the 5000 year Mayan calendar was looking at a long period of time…
Before dawn this morning (from my North American longitude) the Earth reached its closest point to the sun for this year. Did you feel it? No, but this annual event (this time at 6:36 UTC or 01:36 a.m. EST) is called perihelion from the Greek roots peri (near) and helios (sun).
Our planet gets closest to the sun every year in early January. Obviously, that doesn’t make it any warmer in the Northern Hemisphere, and we aren’t any cooler in early July when the aphelion occurs and we are farthest away from the sun. I’ll bet this confused the ancients (and some modern readers) if they knew it was occurring, though the Southern Hemisphere ancients must have thought it made perfect sense.
Earth is about 5 million kilometers (3 million miles) closer to the sun in early January than it will be in early July. That sounds like a big difference, but it’s not really significant enough to cause temperature changes across the planet and it doesn’t explain the seasons.
Mostly, it is the tilt of our planet’s axis that creates winter and summer. In winter, your hemisphere is tilted away from the sun and in summer it is tilted toward the sun. Those days of maximum tilt toward or away from the sun are the December and June solstices.
There’s a page on perihelion and aphelion and all the upcoming dates at astropixels.com if you want more information.
“Autumn is a second spring where every leaf is a flower.” ~ Albert Camus
If you want music while reading this, try a bit of “Autumn” from Vivaldi’s The Four Seasons
On Monday, September 22 at 10:29 P.M. EDT, the autumnal equinox will click into place and fall will arrive here in Paradelle and for the rest of the Northern Hemisphere.
Even though many Americans take Labor Day weekend as the end of summer, and plenty of schoolchildren see the day before school reopens as the end, officially it will be tomorrow. The temperatures will gradually drop and the hours of daylight will lessen.
The word equinox is from the Latin words for equal + night, although we know now that it is not exactly equal with 12 hours of daylight and 12 hours of darkness. On both equinoxes, the very center of the Sun sets 12 hours after it rises. Of course, we consider the day to begin when the upper edge of the Sun peaks over the horizon a bit ahead of the Sun’s center. And, no matter what the clock says, most of us don’t think of it as night until the entire Sun disappears at that opposite horizon.
If you want to get all scientific, the Sun is still visible when it is below the horizon because our atmosphere refracts the rays and bends them in an arc over the horizon.
Not exactly equal, but pretty close.
This autumnal equinoxes and the spring equinoxes are the only days of the year in which the Sun crosses the celestial equator, in other words, the solar terminator is perpendicular to the Equator. So, if equality is what you seek on the equinox, these are the days when the Northern and Southern Hemispheres are illuminated equally.
I prefer the terms “vernal equinox” and “autumnal equinox” which also come from Latin (ver = spring and autumnus = autumn). Unfortunately, these name are seasonal and most people know that seasons of the northern hemisphere and southern hemisphere are opposites. Our autumnal event is the vernal equinox in the southern hemisphere. Have a nice Spring all of you down there!
Still, I suspect that this is likely to be the day that the most people actually think to try and do it.
You just need patience and a steady hand. You can cheat a bit and shake up the egg first to break the yolk loose from the chalazae that keep it suspended in the center of the egg. That will lower the egg’s center of gravity.
Some people also make the false claim that you can balance a broom on the equinox. You might be able to balance your checkbook if, again, you have a steady hand.
The leaves are falling, falling as from way off,
as though far gardens withered in the skies;
they are falling with denying gestures.
And in the nights the heavy earth is falling
from all the stars down into loneliness.
We all are falling. This hand falls.
And look at others: it is in them all.
And yet there is one who holds this falling
endlessly gently in his hands.
~ Ralph Waldo Emerson, “Autumn”
As hemisphere-centric as most of us can be, we are all very Earth-centric. Equinox is a phenomenon that can occur on any planet with a significant tilt to its rotational axis.
The equinox would be a much bigger deal on Saturn. That planet’s equinox occurs only once in about 15 Earth years. I’ll bet there are lots of posts about the equinox on Saturn’s version of Facebook every 15 years.
When Saturn’s equinox does occur, those majestic rings we all know pick up almost no light, so if you view it from Earth the view of the rings during equinox is extremely foreshortened and limited.
But we have eyes in the sky. Cassini-Huygens (an unmanned spacecraft) orbits Saturn and is always taking photos. The shot below is from its wide-angle camera and composed of many exposures taken over about 8 hours patched into a mosaic. It shows the rings and a few of its moons a day and a half after exact Saturn equinox, when the Sun’s disk was exactly overhead at the planet’s equator.