Search found 5 matches
- Tue Nov 08, 2005 3:17 am
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD 2005/11/04 colours of nebulae
- Replies: 5
- Views: 2475
colours of nebulae
I'm not so sure "accompanying links" clear the issue up, in fact I see a continuation of misunderstanding with citing Rayleigh scattering (which produces blue sky). If blue light is either scattered or reflected, we could not see the nebulae as blue. It must be the other end of the spectru...
- Tue Nov 08, 2005 3:01 am
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD 2005/11/04 colours of nebulae
- Replies: 5
- Views: 2475
colours of nebulae
For those who haven't seen the optical phenomenon the "second full moon in a month" might qualify as a "blue moon" but, in optics, there is a real phenomenon that actually produces a moon that is coloured blue. This phenominal blue moon is much rarer than the "calendar"...
- Mon Nov 07, 2005 10:56 pm
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD 2005/11/04 colours of nebulae
- Replies: 5
- Views: 2475
APOD 2005/11/04 colours of nebulae
"... M78, is just below centre in this sharp wide field view, covering an area north of Orion's belt. At a distance of about 1,500 light-years, the bluish nebula itself is about 5 light-years across. Its blue tint is due to dust preferentially reflecting the blue light of hot, young stars in th...
- Tue Jun 21, 2005 4:23 pm
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: Blue or red sky
- Replies: 5
- Views: 3875
blue sun in red sky at sunset on Mars
The APOD for June 20 2005 showing a blue setting sun in a red sky appears to be very strong evidence that the size of the dust particles in the sky of Mars includes a significant proportion at the appropriate size (about twice the wavelength of visible light) to cause Mei scattering of red wavelengt...
- Tue Jun 21, 2005 3:43 am
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: once in a blue moon
- Replies: 1
- Views: 2500
once in a blue moon
An atmospheric layer of particles (such as from volcanic activity or forest fires) between an observer and the moon scatters red light to leave direct light from the moon a blue colour. This is the origin of the expression "once in a blue moon" because this is a very rare occurrence. In Se...