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Pure coincidence?

Off-topic Star Charts
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Danny Caes avatar
Danny Caes avatar
When I look at chart 339 of Wil Tirion's Uranometria 2000.0 star atlas (1987), I see the crossing of the galactic equator and the ecliptic in Sagittarius. Is it pure coincidence that this crossing is at the most southern section of the ecliptic? (at 270° of the ecliptic). The same (of course) is noticeable at chart 136, in Taurus. The most northern section of the ecliptic is crossing the galactic equator (at 90° of the ecliptic).
What if both the ecliptic and the galactic equator were "one and the same line"? It is a possibility (or not?).
Well Written Engaging
andrea tasselli avatar
andrea tasselli avatar
Actually, it isn't. Close, but not quite coincident.
Dave Erickson avatar
Dave Erickson avatar
=ILfuVd=hgKElcThe answer lies in Precession of the Equinoxes. The points of intersection between the celestial equator and the =c5aZPb=JPfdseecliptic shift westward along the ecliptic at a rate of about 50 minutes of arc per year or over 1º per century. Thus, the equinoxes precess completely around the ecliptic in 25,868 years.
Concise
Oscar avatar
Oscar avatar
to me, you guys sound like you are speaking another language smile
andrea tasselli avatar
andrea tasselli avatar
Dave Erickson:
=ILfuVd=hgKElcThe answer lies in Precession of the Equinoxes. The points of intersection between the celestial equator and the =c5aZPb=JPfdseecliptic shift westward along the ecliptic at a rate of about 50 minutes of arc per year or over 1º per century. Thus, the equinoxes precess completely around the ecliptic in 25,868 years.

Equator isn't the Galactic equator.
Danny Caes avatar
Danny Caes avatar
And... (thanks Andrea, I understand, or rather: I TRY to understand), but... (another question)... who was responsible for the... how should I call it... the "graphic representation" of our galaxy's equator? (who discovered the exact centre of our galaxy, and decided, from there onward, to draw the "continuing line" north and south of the centre until both lines meet each other at the location of the galaxy's anti-centre in Auriga, very near the Spaghetti nebula aka Simeis 147 ?
The anti-centre of our galaxy is at 180° away from the galaxy's centre, but... are we (the solar system) really somewhere at 0° North / 0° South in the plane of our galaxy? We could be several lightyears to the north or south of it... (I have to take a look in several online sources to know exactly where we are in our galaxy).

I should make a drawing of what I want to know (if the solar system's location is several lightyears to the north or to the south of the galaxy's plane, then the galaxy's anti-centre is not exactly at 180° of the galaxy's centre).
Dave Erickson avatar
Dave Erickson avatar
andrea tasselli:
Dave Erickson:
=ILfuVd=hgKElcThe answer lies in Precession of the Equinoxes. The points of intersection between the celestial equator and the =c5aZPb=JPfdseecliptic shift westward along the ecliptic at a rate of about 50 minutes of arc per year or over 1º per century. Thus, the equinoxes precess completely around the ecliptic in 25,868 years.

Equator isn't the Galactic equator.

Ah yes, true...thanks..I missed the point
Danny Caes avatar
Danny Caes avatar
Messierman3000, you wrote: to me, you guys sound like you are speaking another language.
Well, thus were my days at school! I wanted to know all sorts of things nobody was thinking or talking about. It was as if I was speaking a language which was non existent or unknown on planet Earth. I didn't want to know about Charlemagne, I wanted to know all about our exact location in the enormous starry and nebulous system called the galaxy, and the exact location of our galaxy in the universe! Alas, the minds of most of the teachers were anchored in the mediaeval dark ages and the hundreds, nay, thousands of years before those dark ages. Sigh...

Suddenly I remember that teacher who was absolutely against the gold plaque aboard one of the interplanetary Pioneer probes. He said: How do they (the NASA scientists) know if those extraterrestrials have eyes to see the picture on that plaque?

At school you get all sorts of answers to questions you never ask or never think about. The questions about those things you really want to know are never answered.
andrea tasselli avatar
andrea tasselli avatar
I did want to know all about Charlemagne but I wasn't told. Pity that…
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