Originally posted by VoidSpiritHow can it happen biannually? Is the sun nearly on the galactic equator? How would you know if it is imaginary? How does one even calculate the galactic equator down to a specific date?
i think they mean it will pass through the imaginary galactic equator.
i don't see what the big deal is, this happens biannually.
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Originally posted by VoidSpiritNot me, but I'm already planning for 2038.
forget 2012, hands up whose planning for the coming zombocalypse?
(And yes, I'm one of those who planned for 2000 in 1995 - not by stocking up on canned beans, but by fixing the bugs written by my predecessors so the rest of you wouldn't need your canned beans.)
Richard
Originally posted by twhiteheadit's an imaginary plane on the galactic disc which contains most of the mass of the galaxy. it's imaginary since it's an arbitrary position agreed upon by convention.
How can it happen biannually? Is the sun nearly on the galactic equator? How would you know if it is imaginary? How does one even calculate the galactic equator down to a specific date?
most of the stars in our galaxy have orbits near this plane and likely go through it just as our star does.
Originally posted by Shallow BlueYeah but the same thing is due to happen all over again after the year 9999. What do you plan to do about THAT one, eh?🙂
Not me, but I'm already planning for 2038.
(And yes, I'm one of those who planned for 2000 in 1995 - not by stocking up on canned beans, but by fixing the bugs written by my predecessors so the rest of you wouldn't need your canned beans.)
Richard
Originally posted by sonhouseAccording to scientists/atheists he'll be down a few layers, so lets all meditate on that,eh?
Yeah but the same thing is due to happen all over again after the year 9999. What do you plan to do about THAT one, eh?🙂
Either that or in many different places, but still similarly disfunctional.
Originally posted by VoidSpiritBut our star would go through it twice for every rotation round the galaxy, not biannually.
it's an imaginary plane on the galactic disc which contains most of the mass of the galaxy. it's imaginary since it's an arbitrary position agreed upon by convention.
most of the stars in our galaxy have orbits near this plane and likely go through it just as our star does.
from earthsky.org :
Earth won’t physically cross the plane of our Milky Way galaxy in 2012, but Earth will cross the galactic equator in 2012. That’s nothing special! As seen from the sun, Earth does this every year – twice. Yes, Earth will cross the galactic equator in 2012. As seen from the sun, the Earth does this every year – twice. However, the Earth won’t be physically passing through the plane of the Milky Way galaxy anytime in the near future.
Here’s some background. The galactic equator is an imaginary great circle that divides the equally imaginary celestial sphere into two equal halves. The celestial sphere is – of course – a fiction. It’s the same fiction that so confounded the early stargazers, that, as seen from Earth, we appear to reside in the center of a great globe of stars. In modern times, the fiction of the geocentric view of the universe enables astronomers to use a workable coordinate system for mapping the sky.
Now let’s define some terms. When someone says galactic equator, they’re usually talking about the coordinate system of astronomers. On this coordinate system, modern astronomers tweak things a bit, to devise a sun-centered way of mapping the Milky Way galaxy. On the other hand, when someone says galactic plane they are most often referring to the real Milky Way galaxy spinning in space. The galactic plane is the actual mid-plane – the flat part – of our galaxy’s huge spinning disk of stars.
What’s tricky is that – when you look at the starry sky at night as seen from Earth – the galactic equator closely follows the plane of the Milky Way galaxy. Of course it does, because we’re talking about the real Milky Way in our sky.
As seen from the sun, the Earth crosses the galactic equator twice a year, every year. Nothing special here. Keep moving.
As seen from Earth, the sun crosses the galactic equator twice a year, every year. Keep moving.
As seen from Earth, the moon crosses the galactic equator two (sometimes three) times a month. Are you seeing the pattern here? All of this crossing of the galactic equator is just part of the heavens’ normal motion, really Earth’s normal motion as projected on our sky’s dome as we travel around the sun.
Back to 2012. There’s been much hoopla about the winter solstice sun aligning with galactic plane on December 21, 2012. You, however, now know the reality that, as seen from Earth, the sun crosses the galactic equator twice a year. And the galactic equator on our sky’s imaginary astronomical coordinate system more or less corresponds with the plane of the Milky Way galaxy. So, in this sense, the sun crosses the plane of the Milky Way twice a year (as seen from Earth). Quite by coincidence, the great circle of the ecliptic – the projection of the Earth’s orbital plane onto the celestial sphere – intersects the galactic equator near the solstice points. According to the computational wizard Jean Meeus*, the solstice points were in alignment with the galactic equator as recently as the year 1998 – in other words, they were closer on the sky’s dome then. But in 2011 and 2012, these points – the solstice point, and the point where the sun crosses the galactic equator – are near each other on our sky’s dome.
It’s true that the sun on the December solstice doesn’t return to the same exact spot in front of the backdrop stars every year. The solstice point slowly but surely moves westward through the stars at about one degree per every 72 years. (For reference, the sun’s diameter equals about 1/2 degree.) Therefore, the solstice point moves about 30 degrees westward every 2,160 years. By the year 2269, the December solstice point will cross into the constellation Ophiuchus. Then the solstices won’t happen so near the location of the galactic equator in our sky.
Take a look at our sky chart. If you could see the stars during the daytime, you’d see the sun in front of the constellation Sagittarius on each December 21 solstice. We show Sagittarius as a Teapot on this sky chart, because many people are able to see that pattern. On or near each December solstice, the sun crosses the galactic equator above the spout of the Teapot, a bit north of the galactic center. Can you see that intersection? If you were standing under the real sky on a dark, moonless night, you could see the great boulevard of stars that we call the Milky Way running astride the galactic equator.
Scientific studies indicate that the solar system lies several dozen light-years north of the galactic plane. What’s more, we are continuing to travel northward, away from the plane of our Milky Way galaxy, at some 7 kilometers per second. Therefore, we won’t be physically passing through the galactic plane in 2012 or anytime in the near future.
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Originally posted by sonhouseNothing. If anyone is still using a program I wrote in 9999, he's got worse problems than just the Y10k one!
Yeah but the same thing is due to happen all over again after the year 9999. What do you plan to do about THAT one, eh?🙂
Besides, it's doubtful there will be a year 9999. There's never been one before, not even in the calendars whose year 1 is a few millennia before the calendar was set up. By the Dionysian year 9999, we'll probably be using the Zua'X!plian calendar, based on Trekkie star dates.
Richard