Period of Aquila (Latin: 'eagle') constellation

[mabs239]

Ref: http://www.bbc.co.uk/dna/h2g2/A29019332

Does this constellation appears moving from the Earth's reference? I have just read that it travels the 12 zodiacal constellations with a speed of about 67 years per degree. Any thoughts about it?

Just found that it is the star Altair (http://en.wikipedia.org/wiki/Altair) for which I want to know the period of revolution around zodiac.

[Vanadium 50]

The proper motion of Altair is 100x slower than that, and it does not go traveling through the zodiac". It's not even in the zodiac: as you point out, it's in Aquilla.

[mabs239]

I know that it is not in zodiac. Just wanted to know it it changes positions w.r.t the zodiac constellation. You said it is 100 times slower, it is new information. So it moves then?

[mabs239]

Today I have been reading an article attributed to an Indian Muslim scholar, Hazrat Ahmed Raza Khan Brelvi of 20th century. He has analyzed the age of Pyramids of Egypt on basis of the theory: "The pyramids were built when the constellation of Aquila was in cancer."
It is said to be stemmed from a picture/shape on those pyramids of a vulture holding a cancer.

A google search directed me to a book "Nuzhat-al-qulub" written in middle ages by a Muslim Iranian scholor Ḥamdollāh Mostowfī’s(died after 1340) [http://www.britannica.com/EBchecked/topic/421352/Nuzhat-al-qulub]



There is a similar sentence in the book: "The pyramids were built when the constellation of Aquila was in cancer." Writer said that the Aquila is in after part of Capricorn.

http://books.google.com.pk/books?id=DaDrEnQlwUIC&pg=PA269&lpg=PA269&dq=egypt+pyramids+with+aquila&source=bl&ots=n4fufp1VP-&sig=WtK0OzgB2w-k7fyinyEk_VBf3Lo&hl=en&ei=CrLdSsuTIoyMkAWm6qAY&sa=X&oi=book_result&ct=result&resnum=10&ved=0CC0Q6AEwCQ#v=onepage&q=aquila&f=true
Page: 269

I have just looked in Google sky and it seems to me that this constellation is in Sagittarius. I hope it is not going in opposite direction as compared to the Sun. Also my judgment is not so good.

My first post was written with this theory in mind. Can you shed some light?

[mgb_phys]

The constellation doesn't move - and even the proper motion of altair is small enough 0.5"/year that there is almost no visible difference in it's position over a few thousand years.

[mabs239]

mgb_phys,

Could you please give a reference where I could find the speed of the star? I have found the rotational speed of Altair but not its traveling speed. Do we have record of a few hundred years back?

Another book which quotes that the Altair moves by 1 degree in 100 years, though old one:

http://books.google.com.pk/books?id=kN9a-QJlY1QC&pg=PA63&dq=altair+pyramids#v=snippet&q=hundred&f=false

[Vanadium 50]

Let me make a few points: first, PF stands for Physics Forums, not Pseudoscience Forums. Please refamiliarize yourself with the PF Rules if you have any questions about what is or is not allowed here. If this thread gets into astrology or new age egyptology, this thread will be immediately closed.

Now, as mgb_phys said, the constellation doesn't move. Single stars do move in the sky - it's called proper motion - but Altair, a) is moving 100x more slowly than you suggest, and b) isn't moving in the right direction.

It's possibly that someone is talking about the astrological zodiac rather than the astronomical one. I have no idea if this makes what's written more logical, as I am not an expert in astrology. Like I said, we don't discuss pseudoscience here.

Finally, it looks like this whole thing is an attempt to date the pyramids as being ~10000 years old. This is not possible - organic material in the mortar has been radiocarbon dated to be about 5000 years old.

[mgb_phys]

Could you please give a reference where I could find the speed of the star? I have found the rotational speed of Altair but not its traveling speed. Do we have record of a few hundred years back?
http://webviz.u-strasbg.fr/viz-bin/VizieR-5?-out.add=.&-source=V/50/catalog&recno=7557
Proper motion is 0.536"/yr in RA (essentially east-west) and 0.386"/yr in dec
An " is 1/3600 of a degree and is about the smallest angle you can measure through the atmosphere without modern technology.
We have accurate records of it's position going back at least 400 years to Tycho and reasonably good ones going back 1000s of years to the greeks.

Another book which quotes that the Altair moves by 1 degree in 100 years, though old one:
From the page you quoted, that book is complete gibberish.

The proper motion is a small local motion - because Altair is close its random motion relative to us is measurable. It does not go around the zodiac however long you wait.
What they may (deliberately or otherwise) be confusing it with is 'precession' where all the stars in the sky move gradually - this is noticeable over long times - it changes which was the North star for example. This has a rate of around 1deg/72 years and takes 26,000 years to get back to it's original position

[mabs239]

Thanks mgb_phys,

From the page you quoted, that book is complete gibberish.
Yes, looks like so.

I wanted to check the astronomical part of the statement. When all the stars look moving then there is no question of Altair moving in or out of a zodiac constellation. I hope I understood you right.

[mgb_phys]

Altair might eventually move out of it's constellation. By the way 'zodiac' constellations are those 12 on the elliptic and Altair is currently moving away from that (increasing dec) .

Another thing that sometimes confuses people is that stars are not attached to constellations - the constellations are just arbitrary 2d grids drawn on the sky. Seen from any other direction the stars,spread out through 3d, would have a different arrangement.

The proper motion is an essentially random motion of nearby stars - along with the sun they are all moving in an orbit around the galaxy mostly fixed relative to each other. But because each star feels slightly different effects from those around it there is a small difference in their speeds and directions. There is no period to this.

[Vanadium 50]

By the way 'zodiac' constellations are those 12 on the elliptic

If I can quibble, it's actually 13. Ophiuchus is also on the ecliptic, but it never got assigned its own astrological sign.

Seems unfair to poor Ophiuchus.

[mgb_phys]

If I can quibble, it's actually 13. Ophiuchus is also on the ecliptic, but it never got assigned its own astrological sign.

Seems unfair to poor Ophiuchus.
Not to mention how it must impact the accuracy of astrologer's predictions!