Upside Down Plough

[Zacs-Master]

I've watched the constellation of The Plough turn from how I normally see it to standing on its tail to now being virtually upside down. I can't recall seeing it n this position in the whole of my 50 years on this planet. Is there something unusual happening, or have I just been un observant ?

[twofeathers]

Northern circumpolar stars move position all night long. In otherwords it rotates arond the pole star!

http://en.wikipedia.org/wiki/Circumpolar_star

[jim360]

The Plough should rotate (along with the rest of the night sky) about a fixed point -- roughly speaking, the Northen Star -- and therefore change its orientation, both in the course of a single night and over a year. So I suppose the answer really is that yes, you have been unobservant.

[twofeathers]

^^^^ Around

[Slapshot]

You think that's tough..... I've been trying to work my head round the southern night sky for the last 18 months, just when I think I've got it, it throws me a curve ball... Orion with an erection rather than the sword.... ;0) Still when the skies let you do this.....

http://i210.photobucket.com/albums/bb6/Slapshot_3/longshot2.jpg

And this...

http://i210.photobucket.com/albums/bb6/Slapshot_3/IMG_8610.jpg

you don't mind the curveballs... ;)

[LazyGun]

Love that picture of the moon especially, Slapshot :)

[mibn2cweus]

For Northern Hemisphere observers the constellations revolve (anti-clockwise) around the North Celestial Pole one complete revolution in just under 24 hours, returning to within about one degree of where they were at about the same time (approximately four minutes earlier) the previous night. This slow 'daily' progression brings the stars back around close to the same position they occupied at the same time and day in previous years.

As a consequence of Earth's daily rotation with respect to the stars the 'plough' will be turned on it tail once every 24 hours at a time which varies with the Earth's annual orbit of the Sun which determines which half of the celestial sphere appears at a given time of the night.

http://www.madsci.org/posts/archives/2000-10/970648986.As.r.html

http://www.physics.sfasu.edu/markworth/notes/Skymotionnotes.htm

http://curious.astro.cornell.edu/question.php?number=493

[Zacs-Master]

Just me then. Many thanks.

[Peter Pedant]

It IS just you innit Z-M
from what the fella says, if it on its head, you are viewing it at a different time of day than in the 50y previously

[Slapshot]

http://i210.photobucket.com/albums/bb6/Slapshot_3/startower21728x2592.jpg

about an hour ago

[sidkid]

@mibn2cweus - //For Northern Hemisphere observers the constellations revolve (anti-clockwise) around the North Celestial Pole one complete revolution in just under 24 hours//
Surely they revolve clockwise?

[mibn2cweus]

Clockwise motion is based on the motion of shadows on the face of a sundial. Shadows move in a direction opposite that of the light source, in this case the apparent east to west motion of the Sun.

http://en.wikipedia.org/wiki/Clockwise#Origin_of_the_term

[sidkid]

Don't see the relevance. I still think that from the Northern hemisphere the stars move around the north star in a clockwise direction. (obviously they don't move at all but the rotation of the earth makes them appear to move.) What does this have to do with shadows and light sources?

[ToraToraTora]

sidkid, the stars move anti clock wise in the northern hemisphere. This is how to visualise. Imagine you are looking down on the north pole, now flatten the earth to a disc and raise the whole thing above your head. Now looking up through it you will see that it rotates clockwise. To any fixed point the stars will move anticlockwise around polaris.

[jomifl]

Viewed from above the north pole the earth will appear to rotate anti-clockwise so the stars viewed from the north pole will appear to rotate clockwise.

[twofeathers]

Or you could just watch the whole thing happening on post 1

The link shows the movement and also explains everything else thats been said

[ToraToraTora]

that would be anticlockwise as stated then.

[mibn2cweus]

If you look up while spinning anti-clockwise then the sky appears to be spinning in the same direction . . . anti-clockwise.

The direction the stars in the night sky appear to rotate depends on whether you're looking north (anti-clockwise) or south (clockwise).

[mibn2cweus]

must post videos separately in individual posts . . . ok

http://www.youtube.com/watch?v=BYy0EQBnqHI

[mibn2cweus]

Another long one

http://www.youtube.com/watch?v=nam90gorcPs

[jomifl]

Mibs, you ain't wrong:o)