Search found 1565 matches
- Sun Feb 25, 2007 12:24 pm
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: battered moon (APOD 25 Feb 2007)
- Replies: 20
- Views: 6070
Because the Moon was not always tidally locked to the Earth. When it was formed, it would have had its own rotation. See: http://en.wikipedia.org/wiki/Tidal_locking The original cratering was probably even all over the Moon. The later maria formed where the crust was thinner, smoothed out the crater...
- Tue Feb 20, 2007 10:27 pm
- Forum: The Observation Deck: Latest Sky Photography
- Topic: New impact on Mars
- Replies: 3
- Views: 3630
Hey, CC, keep up.
Although no one took up the challenge here, there was a PREVIOUS illuminating but not explanatory exchange of views on BAUT: http://www.bautforum.com/showthread.php?t=52156
John
Although no one took up the challenge here, there was a PREVIOUS illuminating but not explanatory exchange of views on BAUT: http://www.bautforum.com/showthread.php?t=52156
John
- Sat Feb 10, 2007 10:32 pm
- Forum: The Asterisk Café: Discuss Anything Astronomy Related
- Topic: Craters are an optical illusion?
- Replies: 16
- Views: 6969
Seeing things in 'reverse' on such pictures is common. Much of our 'seeing' is processing in the eye and brain, that relies on familiar cues and light direction. When those are absent, we cannot 'see' things as they are. A famous illusion relies on this - as in the staircase on this page: http://wil...
- Fri Jan 26, 2007 6:14 pm
- Forum: The Observation Deck: Latest Sky Photography
- Topic: hubble's photos of regular matter and dark matter
- Replies: 3
- Views: 3779
- Fri Jan 26, 2007 6:14 pm
- Forum: The Observation Deck: Latest Sky Photography
- Topic: hubble's photos of regular matter and dark matter
- Replies: 3
- Views: 3779
- Tue Jan 16, 2007 12:50 pm
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: Kepler's Supernova Remnant in X-rays (2007 Jan 16)
- Replies: 4
- Views: 2846
- Fri Jan 12, 2007 5:06 pm
- Forum: The Observation Deck: Latest Sky Photography
- Topic: Circumhorizontal Arc [Fire Rainbow]
- Replies: 15
- Views: 16065
Rather more useful links are found aplenty by Googling for 'circumhorizontal', or just going to the Wikipedia entry:
http://en.wikipedia.org/wiki/Circumhorizontal_arc
How are you going to link this in with interplanetary war, CC?
John
http://en.wikipedia.org/wiki/Circumhorizontal_arc
How are you going to link this in with interplanetary war, CC?
John
- Mon Jan 01, 2007 11:13 am
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: Stereo effect (APOD 12 Dec 2006)
- Replies: 2
- Views: 1667
- Sun Dec 31, 2006 11:57 am
- Forum: The Observation Deck: Latest Sky Photography
- Topic: New impact on Mars
- Replies: 3
- Views: 3630
New impact on Mars
http://www.nasa.gov/mission_pages/mars/ ... 09023.html
Love to read discussion of the assymtry of this impact. Rays to one side, secondary cratering to thhe other.
John
Love to read discussion of the assymtry of this impact. Rays to one side, secondary cratering to thhe other.
John
- Fri Dec 15, 2006 5:38 pm
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: mountains of titan (APOD 14 Dec 2006)
- Replies: 4
- Views: 2047
- Fri Dec 15, 2006 1:50 pm
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: mountains of titan (APOD 14 Dec 2006)
- Replies: 4
- Views: 2047
- Fri Dec 15, 2006 12:06 am
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: Phobos: Irregular Shape? (APOD 3 Dec 2006)
- Replies: 43
- Views: 15218
ERROR ALERT!
My apologies. I wrote above that: If the ball enters a smaller gravity field with a steeper gradient, like that of a planet, then objects on the far side of the CCoM from the planet are going too slow for their new orbit; they experience a force pulling them away from the planet into a higher slower...
- Tue Dec 12, 2006 9:07 am
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: Moon Panorama: shadows, dust, stars? (APOD 10 Dec 2006)
- Replies: 26
- Views: 9935
- Tue Dec 12, 2006 1:15 am
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: Moon Panorama: shadows, dust, stars? (APOD 10 Dec 2006)
- Replies: 26
- Views: 9935
If you are a good enough photographer, you can use flash and see stars in the result! See the work of Wally Pacholka. Some of his work looks as if it is staged, such as this one, where the mesas appear to cast a flash shadow on the starry background! Obviously a stage set! http://www.ocastronomers.o...
- Tue Dec 12, 2006 1:04 am
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: Moon Panorama: shadows, dust, stars? (APOD 10 Dec 2006)
- Replies: 26
- Views: 9935
Bob, I feel your pain! But maybe we're just too geocentric, deposition would be quite unlike Earthly windblown detritus. And look at two places in that pic: 1/ the lumpy rock, aboput four o'clock from the astronaut. There's dust in the depressions and 'lapping' up the sdie nearest the camera that's ...
- Sat Dec 09, 2006 11:23 pm
- Forum: The Asterisk Café: Discuss Anything Astronomy Related
- Topic: "Report this post" button needed?
- Replies: 6
- Views: 3450
- Fri Dec 08, 2006 10:45 pm
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: Antikythera Mechanism (2006 Dec 05)
- Replies: 30
- Views: 11920
13, your example of the shuttle is appropriate. I read, and it seems more than likely, that unless the promise of funding and opportunity for NASA to go to the Moon again soon, like in the next ten years, most of those with the experience of the Apollos will be dead. An enormous storehouse of expert...
- Fri Dec 08, 2006 11:12 am
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: Antikythera Mechanism (2006 Dec 05)
- Replies: 30
- Views: 11920
All, In contrition for having hijacked the thread, may I offer Archimedes' Screw for discussion? This is a much simpler mechanism than the Antikythyra, indeed it is difficult to see how this could have been lead up to by earlier, simpler devices. Can anyone suggest an earlier, simpler device than th...
- Fri Dec 08, 2006 10:59 am
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: Antikythera Mechanism (2006 Dec 05)
- Replies: 30
- Views: 11920
GG, All, Irony is not entirely absent from the Bible, there are some instances. I cannot tell if they were provied by a god or not. Job suffered mightily from the cruelty of Jehova, and lamented mightily too. He was upbraded by his unsympathetic neighbours, who quoted the prophets and the holy law t...
- Fri Dec 08, 2006 10:29 am
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: Phobos: Irregular Shape? (APOD 3 Dec 2006)
- Replies: 43
- Views: 15218
Ken, Thank you! What an interesting and informative paper! It raises a Q for me - Assuming that grooves are just crater chains below the resolution of the photos, the authors suggest that ejecta from Mars impacts caused these markings. Does (do?) 'ejecta' leave the impact site as a 'line of gravel',...
- Thu Dec 07, 2006 11:03 pm
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: APOD: Antikythera Mechanism (2006 Dec 05)
- Replies: 30
- Views: 11920
You're right, Andy, irony is a dangerous form of humour, but one much loved by gods, I fear And when you think about it, a god must have a sense of humour. Sitting about for centuries, while all those little people make such a complete mess of their lives, don't even thank you and when they do it's ...
- Thu Dec 07, 2006 10:43 pm
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: Phobos: Irregular Shape? (APOD 3 Dec 2006)
- Replies: 43
- Views: 15218
13, Since you mention it, may I mention that it is the effect of which you write which causes tidal disruption? That ball of gravel would orbit in a very large gravity field, like the Sun's, with the individual particles orbiting around their common centre of mass (CCoM), or stuck together loosely w...
- Thu Dec 07, 2006 3:48 pm
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: Phobos: Irregular Shape? (APOD 3 Dec 2006)
- Replies: 43
- Views: 15218
Al, Don't forget the resolution of this picture - about 7 meters (an astounding achievement!). This may allow a chain of craters that are 250 meters wide to be seen as craters, but if they are c.25 meters, then the chain will appear as a groove. I fear that even 'dragging' won't work! Gravel thrown ...
- Thu Dec 07, 2006 11:23 am
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: Phobos: Irregular Shape? (APOD 3 Dec 2006)
- Replies: 43
- Views: 15218
- Wed Dec 06, 2006 11:33 pm
- Forum: The Bridge: Discuss an Astronomy Picture of the Day
- Topic: Phobos: Irregular Shape? (APOD 3 Dec 2006)
- Replies: 43
- Views: 15218