Search found 6 matches

by Lucra
Thu Feb 25, 2010 11:26 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Exceptional Rocket Waves Destroy Sun Dog (2010 Feb 23)
Replies: 65
Views: 17421

Re: APOD: Exceptional Rocket Waves Destroy Sun Dog (2010 Feb

By the time the sound waves should reach the left sundog (if there was one) they must have been heavely weakened. In such a way that the effect became most probably unvisible. At 10km high, an apparent distance of 44° between left and right sundog stands for about 8 km.
My geuss,
Luc
by Lucra
Wed Feb 24, 2010 1:19 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Exceptional Rocket Waves Destroy Sun Dog (2010 Feb 23)
Replies: 65
Views: 17421

Re: APOD: Exceptional Rocket Waves Destroy Sun Dog (2010 Feb

Air pressure density ripples, Changing refraction. Slightly . ? Mark Pressure density ripples are rapidly changing pressure variations. As a consequence the gas (air) is periodically heating en cooling with no chance to exchange heat with the surrounding gas (an adiabatic proces). Since temperature...
by Lucra
Tue Feb 23, 2010 4:14 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Exceptional Rocket Waves Destroy Sun Dog (2010 Feb 23)
Replies: 65
Views: 17421

Re: APOD: Exceptional Rocket Waves Destroy Sun Dog (2010 Feb

Hey guys! I find all the talk about breaking the sound barrier and sonic booms confusing. If the rocket was going at mach 1 or faster, there would be no shock waves travelling ahead of the rocket - only in a cone shape behind it. Visually, that seems not to be the case. At the time the ripples appe...
by Lucra
Tue Feb 23, 2010 9:47 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Exceptional Rocket Waves Destroy Sun Dog (2010 Feb 23)
Replies: 65
Views: 17421

Re: APOD: Exceptional Rocket Waves Destroy Sun Dog (2010 Feb

Looking at the form of the ripples I would think this are rather sound waves, probably subsonic, produced by the blast of the rocket. An estimation of the wavelength may help to confirm or contradict this hypothese.
Luc
by Lucra
Wed Mar 05, 2008 7:26 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD of ISS (05 Mar 2008)
Replies: 7
Views: 2558

At the time of undocking the ISS was halfway between South Africa and Australia (S 27° E 77°) Hope this helps to identify the underlaying landmarks. Allow for serious errors due to uncertainty in the time the picture was taken. Since the sun is shining from the left site (at 9h24m UT) the camera poi...
by Lucra
Wed Mar 05, 2008 11:32 am
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD of ISS (05 Mar 2008)
Replies: 7
Views: 2558

Had the same question. If one could know the time (UT) the picture was taken it should be possible to to determine the position of ISS. The only time indication I could find is the time the Shuttle undocked from the station but that, I guess, might not be accurate enough.

Luc