Today in Long Beach is the closest we will come to an even 12 h of "day"/12 h of "night" before the summer solstice. Officially--sunrise @ 0701; sunset @ 1901 but 17 sec short of "dead even."
Is today the true equinox?
- Thread starter Kings Gambit
- Start date
The question is not centered in Long Beach but the Equator, I think.
This being true then no. The Spring Equinox would be on March 20th at 16:15
Wikipedia suggests;
equinox is commonly regarded as the moment when the plane of Earth's equatorpasses through the center of the Sun's disk,[2]which occurs twice each year, around 20 March and 23 September.
But if your considering a ritual moment in Long Beach when spring flings should be celebrated then. Yes. Today is the day. Drink celebrate and be Mary.
This being true then no. The Spring Equinox would be on March 20th at 16:15
Wikipedia suggests;
equinox is commonly regarded as the moment when the plane of Earth's equatorpasses through the center of the Sun's disk,[2]which occurs twice each year, around 20 March and 23 September.
But if your considering a ritual moment in Long Beach when spring flings should be celebrated then. Yes. Today is the day. Drink celebrate and be Mary.
There is also this:
noun
1.
the time when the sun crosses the plane of the earth's equator, making night and day of approximately equal length
all over the earth and occurring about March 21 (vernal equinox or spring equinox) and September 22 (autumnal equinox)
And this
1350-1400; Middle English, Medieval Latin equinoxium, for Latin aequinoctium, the time of equal days and nights.
noun
1.
the time when the sun crosses the plane of the earth's equator, making night and day of approximately equal length
all over the earth and occurring about March 21 (vernal equinox or spring equinox) and September 22 (autumnal equinox)
And this
1350-1400; Middle English, Medieval Latin equinoxium, for Latin aequinoctium, the time of equal days and nights.
Sunrise and Sunset time are affected by both the position of the earth in its orbit and the refraction of sunlight through the atmosphere. The sun will appear to be above the horizon in the AM even with it is slightly below the horizon. The same happens at sunset.
Who's Mary?Today is the day. Drink celebrate and be Mary.
Our equinox was yesterday, 3/15. Sunrise @ 0738 and sunset @ 1938. The astronomical Spring equinox is on March 20th.
Are the times stated in the original post "Daylight Saving Time"? And furthermore, I don't want to be Mary. I'm quite content as I am.
And furthermore, I don't want to be Mary. I'm quite content as I am.
I always look at this and the fall equinox as the time when the sun rises due East and sets due West
The sun only rises and sets Due East and West from anywhere on the globe except for the poles (2) times per year spring and fall equinox's
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Of course there is also the Great Year or Platonic Year. Where the wobble of the Earth's axis goes through a full rotation in about 25,000 years
"It is defined by NASA as "The period of one complete cycle of the equinoxes around the ecliptic, about 25,800 years"
- Will (Dragonfly)
"It is defined by NASA as "The period of one complete cycle of the equinoxes around the ecliptic, about 25,800 years"
- Will (Dragonfly)
Don't they party all the time in Long Beach? What's the big deal? Oh, wait --- just like I used to tell Mom: "Here's today's excuse!"
Yes but, sunrise is when the top edge of the sun comes above the horizon and sunset is when the bottom edge goes below the horizon and so the "day" is longer than the "night" by twice the amount of time it takes for the disc of the sun to traverse the horizon. That is why your solstice is apparently arriving early.
For extra credit look up sidereal vs solar day.
According to the table I'm seeing for Long Beach, the sun rises at 090 and sets at 270 degs T, respectively, on March 18 & 19. Thus, neither of the two empirical criteria we've discussed--equal length of day/night and azimuths of the sun at rise/set, which themselves do not coincide with each other, appear NOT to match in time the astronomical definition, which puts it (equinox) on March 20
. How would we know, lacking a calendar?
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First you find a big field. Then you find some big rocks. Put them in a circle and watch the shadows.According to the table I'm seeing for Long Beach, the sun rises at 090 and sets at 270 degs T, respectively, on March 18 & 19. Thus, neither of the two empirical criteria we've discussed--equal length of day/night and azimuths of the sun at rise/set, which themselves do not coincide with each other, appear to match in time the astronomical definition, which puts it (equinox) on March 20
The geometry of what is happening is infinitely complex. Given the wobble in the Earth's rotation (mentioned by Will above), the fact that the orbit around the sun is not an exact number of either solar or sidereal days, (neither of which is constant compared with say an atomic clock) and the non circular nature of the earth's orbit, and the gravity of the moon and other planets and and and - the deeper you go into it the more impossible it becomes for ordinary mortals. I don't know for certain, but I suspect that at a millisecond (or microsecond?) level it is probably actually chaotic (i.e. non repeating) because the influencing factors are so subtle and asynchronous. I need to talk to one of my astrophysicist buddies.According to the table I'm seeing for Long Beach, the sun rises at 090 and sets at 270 degs T, respectively, on March 18 & 19. Thus, neither of the two empirical criteria we've discussed--equal length of day/night and azimuths of the sun at rise/set, which themselves do not coincide with each other, appear to match in time the astronomical definition, which puts it (equinox) on March 20
The other thing is the equinox happens at a certain instant, and that is the same for every point on earth. For someone it will be midday and for others maybe the day before or the day after.
The Earth's orbit around the Sun is not equally divisible by days (Earth rotations), thus we have leap years, but then, that isn't enough so
for the Gregorian calendar.
- Will (Dragonfly)
for the Gregorian calendar.
- Will (Dragonfly)
