Spiral Galaxies (APOD 24 July 2007)

Comments and questions about the APOD on the main view screen.
tvkrys
Ensign
Posts: 10
Joined: Mon Dec 05, 2005 6:47 pm
Location: Santa Rosa, CA

Spiral Galaxies (APOD 24 July 2007)

Post by tvkrys » Tue Jul 24, 2007 4:08 pm

While looking at today's APOD (Spiral Galaxy M83), I wondered ... do all galaxies appear to rotate clockwise, or are there some that rotate counter-clockwise? If both ways, what are the percentages? If both ways, is that simply because of our vantage point, or is there a physics reason for the difference?

Thanks,
K-
God Bless America!

User avatar
Qev
Ontological Cartographer
Posts: 576
Joined: Wed Mar 08, 2006 8:20 pm

Post by Qev » Tue Jul 24, 2007 4:38 pm

Galaxies appear (to us) to rotate in pretty much any direction, clockwise or counter-clockwise. The Galaxy Zoo project is, in part, studying the distribution of spiral galaxies in either direction, to see if that can tell us anything about how the local universe has evolved over time.
Don't just stand there, get that other dog!

harry
G'day G'day G'day G'day
Posts: 2881
Joined: Fri Nov 18, 2005 8:04 am
Location: Sydney Australia

Post by harry » Wed Jul 25, 2007 7:11 am

Hello Qev

Nice link.

My son loves it.
Harry : Smile and live another day.

Cambridge2007
Asternaut
Posts: 1
Joined: Wed Jul 25, 2007 8:07 pm
Location: Cambridge, UK

QUERY LENSING EFFECTS ON SOUTHERN PINWHEEL IMAGE OF 24 JULY

Post by Cambridge2007 » Wed Jul 25, 2007 8:16 pm

Sorry if its been mentioned already as I am new to forums (fora?).
On the Southern Pinwheel image there are several apparent pairs of images suggesting gravitational lensing though if so surprisingly this was not mentioned in the notes - at 3.30 (o'clock) a pair of similar looking spirals edge on, close by a pair of 'stars' in same orientation, 5 o'clock another pair of stars - similar orientation....

User avatar
BMAONE23
Commentator Model 1.23
Posts: 4076
Joined: Wed Feb 23, 2005 6:55 pm
Location: California

Post by BMAONE23 » Wed Jul 25, 2007 9:22 pm

http://antwrp.gsfc.nasa.gov/apod/image/ ... er_big.jpg

While the two Blue stars @ 3:30 and the two Yellow stars @ 5 appear to have the same apparent luminosity as their opposed twins the two galaxies at 3:30 arent from lensing, the upper one is slightly larger and is rotating clockwise to our perspective while the lower one is smaller and is rotating anti-clockwise. I didn't notice them though my first time looking at the image.

User avatar
bystander
Apathetic Retiree
Posts: 21593
Joined: Mon Aug 28, 2006 2:06 pm
Location: Oklahoma

Post by bystander » Thu Jul 26, 2007 12:29 pm

As the stars are in the foreground, they can't very well be an effect of lensing.
Know the quiet place within your heart and touch the rainbow of possibility; be
alive to the gentle breeze of communication, and please stop being such a jerk.
— Garrison Keillor