Search found 631 matches
- Tue Feb 22, 2011 5:59 pm
- Forum: The Asterisk Café: Discuss Anything Astronomy Related
- Topic: APOD: Spiral Galaxy NGC 2841 Close Up (2011 Feb 19)
- Replies: 69
- Views: 8926
Re: APOD: Spiral Galaxy NGC 2841 Close Up (2011 Feb 19)
Hello Ann, thank you for expressing your wll illustrated ideas about flocculent galaxies and their plumes. You also made another quotable statement about barred galaxies. I liked your hypothesis about the absence of central bars in galaxies which prevents thorough mixing of interstellar materials an...
- Tue Feb 22, 2011 5:10 pm
- Forum: The Library: Information Desk and Educational Resources
- Topic: What favors orbit or collision of two planetoids ?
- Replies: 23
- Views: 1396
Re: What favors orbit or collision of two planetoids ?
I hope you do not mind another question which you just have given me. How do astronomers observe Kuiper belt regions around other stars ? I certainly know how exo-solar planets are observed because of their size, mass, and ecclipses. But how do you observe Kuiper objects such as comets and dwarf pla...
- Tue Feb 22, 2011 5:03 pm
- Forum: The Asterisk Café: Discuss Anything Astronomy Related
- Topic: APOD: Spiral Galaxy NGC 2841 Close Up (2011 Feb 19)
- Replies: 69
- Views: 8926
Re: APOD: Spiral Galaxy NGC 2841 Close Up (2011 Feb 19)
Doug, you asked this: Do you believe that all observable galaxies were created simultaneously within a very short period of cosmic time ? No, I don't believe that all observable galaxies were created simultaneously within a very short period of cosmic time, but I do believe that the vast majority o...
- Tue Feb 22, 2011 3:38 pm
- Forum: The Library: Information Desk and Educational Resources
- Topic: What favors orbit or collision of two planetoids ?
- Replies: 23
- Views: 1396
Re: What favors orbit or collision of two planetoids ?
That leaves one final question in this matter. Where did the Kuiper belt objects including its dwarf planets come from ? From the Oort Cloud ? Or from the leftover remains of the proto-star disk ? Or from ejected objects of the regular solar system (objects inside Neptune's orbit) ? Doug Ettinger, P...
- Mon Feb 21, 2011 2:31 pm
- Forum: The Library: Information Desk and Educational Resources
- Topic: What favors orbit or collision of two planetoids ?
- Replies: 23
- Views: 1396
Re: What favors orbit or collision of two planetoids ?
So how did the Jupiter family of comets come to be ? By theory they came from the Oort Cloud 5 to 10 thousand years ago. On one of their orbits about the Sun they eventually had near crossings with Jupiter in its orbit and were captured in elliptical orbits with high eccentricity around Jupiter. All...
- Mon Feb 21, 2011 2:40 am
- Forum: The Library: Information Desk and Educational Resources
- Topic: What favors orbit or collision of two planetoids ?
- Replies: 23
- Views: 1396
Re: What favors orbit or collision of two planetoids ?
Why cannot astrophysists be certain about the capture of the iregular moons of Mars ? And more than likely they came from the Asteroid Belt. What other mechanism exists for the reason for these Martian moons ? The moons may have coalesced in place, during or shortly after the formation of Mars. The...
- Mon Feb 21, 2011 1:33 am
- Forum: The Asterisk Café: Discuss Anything Astronomy Related
- Topic: APOD: Spiral Galaxy NGC 2841 Close Up (2011 Feb 19)
- Replies: 69
- Views: 8926
Re: APOD: Spiral Galaxy NGC 2841 Close Up (2011 Feb 19)
Hello Ann, you made a quotable statement in stating your own estimation of how many generations of O-type stars occurred in our galaxy. I like the way that your thoughts wander beyond the box and how you Create your very own ideas. You can both answer questions by "nuefing" them and by bei...
- Sun Feb 20, 2011 2:46 pm
- Forum: The Asterisk Café: Discuss Anything Astronomy Related
- Topic: APOD: Spiral Galaxy NGC 2841 Close Up (2011 Feb 19)
- Replies: 69
- Views: 8926
Re: APOD: Spiral Galaxy NGC 2841 Close Up (2011 Feb 19)
Hello Ann, thanks for your thoughtful response. Discussing such topics as Hoag objects, flocculent galaxies, and ring galaxies really expands my knowledge. Are you perhaps an astrophysicist specializing in galaxies. Irregardless, I have an interesting question. Is there any theory regarding the age ...
- Sat Feb 19, 2011 8:28 pm
- Forum: The Library: Information Desk and Educational Resources
- Topic: What favors orbit or collision of two planetoids ?
- Replies: 23
- Views: 1396
Re: What favors orbit or collision of two planetoids ?
The irregular satellites of Mars and the outer planets were not part of the primordal proto-planetary disk. These satellites were captured possibly from perturbations of objects originally in the Asteroid Belt. Very simply - how did these captures occur ? It is by no means certain that the satellit...
- Sat Feb 19, 2011 7:57 pm
- Forum: The Asterisk Café: Discuss Anything Astronomy Related
- Topic: APOD: Spiral Galaxy NGC 2841 Close Up (2011 Feb 19)
- Replies: 69
- Views: 8926
APOD: Spiral Galaxy NGC 2841 Close Up (2011 Feb 19)
http://apod.nasa.gov/apod/ap110219.html This flocculent galaxy, NGC 2841, appears to have definite plumes throughout the last 2/3's of its disk radial distance. It appears that the plumes are hiding the majority of stars including the galaxy's spiral structure. Could these plumes be the result of al...
- Thu Feb 17, 2011 10:06 pm
- Forum: The Library: Information Desk and Educational Resources
- Topic: Oort Cloud (split from: Lecture 11: Comets and Meteors)
- Replies: 10
- Views: 759
Re: Lecture 11: Comets and Meteors
I also recall that APOD. Why cannot we see this ice ring or ice signature around stars nearby to the Sun? The interstellar densities of objects could be much higher than expected or measured. I don't think so. The density required to produce the observed cometary flux would be high enough that we'd...
- Thu Feb 17, 2011 9:18 pm
- Forum: The Library: Information Desk and Educational Resources
- Topic: Oort Cloud (split from: Lecture 11: Comets and Meteors)
- Replies: 10
- Views: 759
Re: Lecture 11: Comets and Meteors
I also recall that APOD. Why cannot we see this ice ring or ice signature around stars nearby to the Sun? Since many comets have high inclinations it then is assumed that the comet sink or source is spherical like the Oort Cloud is envisioned. Comets could not have been perturbed into such high inc...
- Thu Feb 17, 2011 8:37 pm
- Forum: Starship Asterisk: Handbook
- Topic: Help on using BBCode
- Replies: 35
- Views: 670136
Re: Help on using BBCode
Yes, Owlice, an indentation rule for different quotes is a good idea.
Doug Ettinger
Doug Ettinger
- Thu Feb 17, 2011 8:32 pm
- Forum: The Library: Information Desk and Educational Resources
- Topic: Oort Cloud (split from: Lecture 11: Comets and Meteors)
- Replies: 10
- Views: 759
Re: Lecture 11: Comets and Meteors
I also recall that APOD. Why cannot we see this ice ring or ice signature around stars nearby to the Sun? If recent exoplanet discoveries have taught us anything, it's that there's a huge variability in the structure of planetary systems. One possibility is that most stars don't have Oort clouds. A...
- Thu Feb 17, 2011 7:33 pm
- Forum: Starship Asterisk: Handbook
- Topic: Help on using BBCode
- Replies: 35
- Views: 670136
Re: Help on using BBCode
Owlice, I do not have the slightest clue of what a horizontal rule is. Are you referring to margins ?
Trying to follow the BBCode rules,
Doug Ettinger
Trying to follow the BBCode rules,
Doug Ettinger
- Thu Feb 17, 2011 7:26 pm
- Forum: The Library: Information Desk and Educational Resources
- Topic: What favors orbit or collision of two planetoids ?
- Replies: 23
- Views: 1396
Re: What favors orbit or collision of two planetoids ?
If I know the masses of a possible parent planet and "the near-eccounter-passing object", the minimum passing distance, and the velocity of the passing object, is there any reference or equation(s) that can predict whether it will be captured into an elliptical orbit or simply pass by in ...
- Thu Feb 17, 2011 3:36 pm
- Forum: The Library: Information Desk and Educational Resources
- Topic: What favors orbit or collision of two planetoids ?
- Replies: 23
- Views: 1396
Re: What favors orbit or collision of two planetoids ?
What were the differences in the parameters that caused a comet to spiral inward and hit Jupiter and caused numerous irregular moons to orbit Jupiter at some time in the distant past ? I don't understand the question. What "parameters" are you referring to? SL-9 did not spiral inward and ...
- Wed Feb 16, 2011 10:57 pm
- Forum: The Library: Information Desk and Educational Resources
- Topic: Oort Cloud (split from: Lecture 11: Comets and Meteors)
- Replies: 10
- Views: 759
Re: Lecture 11: Comets and Meteors
I am curious to know what observations were made to see such Oort Cloud structures around other stars. Are these stars nearby such as less than 15 ly's ? Should we not see this structure around our closest star system that is 4 ly's away ? I don't have a reference off-hand. I seem to recall there w...
- Wed Feb 16, 2011 9:18 pm
- Forum: The Library: Information Desk and Educational Resources
- Topic: What favors orbit or collision of two planetoids ?
- Replies: 23
- Views: 1396
Re: What favors orbit or collision of two planetoids ?
I am alluding to certain examples in the solar system. They are irregular satellites of Mars and the outer planets that were mostly captured. Also, the moons of dwarf planets including those of Pluto are other examples. In the Asteroid Belt, I remember seeing photography from space probes of at lea...
- Wed Feb 16, 2011 5:50 pm
- Forum: The Library: Information Desk and Educational Resources
- Topic: Oort Cloud (split from: Lecture 11: Comets and Meteors)
- Replies: 10
- Views: 759
Re: Lecture 11: Comets and Meteors
Chris, thanks for your prompt and determined follow-up and patience. I am curious to know what observations were made to see such Oort Cloud structures around other stars. Are these stars nearby such as less than 15 ly's ? Should we not see this structure around our closest star system that is 4 ly'...
- Wed Feb 16, 2011 5:31 pm
- Forum: The Library: Information Desk and Educational Resources
- Topic: What favors orbit or collision of two planetoids ?
- Replies: 23
- Views: 1396
Re: What favors orbit or collision of two planetoids ?
I am alluding to certain examples in the solar system. They are irregular satellites of Mars and the outer planets that were mostly captured. Also, the moons of dwarf planets including those of Pluto are other examples. In the Asteroid Belt, I remember seeing photography from space probes of at leas...
- Wed Feb 16, 2011 4:58 pm
- Forum: The Library: Information Desk and Educational Resources
- Topic: Oort Cloud (split from: Lecture 11: Comets and Meteors)
- Replies: 10
- Views: 759
Re: Lecture 11: Comets and Meteors
I have asked this question previously, but perhaps some new data has changed the answer. Is there any physical evidence to collaborate the existence of the Oort Cloud which is supposely the source of comets that keep visiting the inner solar system? I'd say you answered your own question. The exist...
- Wed Feb 16, 2011 4:33 am
- Forum: The Library: Information Desk and Educational Resources
- Topic: Oort Cloud (split from: Lecture 11: Comets and Meteors)
- Replies: 10
- Views: 759
Oort Cloud (split from: Lecture 11: Comets and Meteors)
I have asked this question previously, but perhaps some new data has changed the answer. Is there any physical evidence to collaborate the existence of the Oort Cloud which is supposely the source of comets that keep visiting the inner solar system ? I just wonder how less plausible it would be that...
- Wed Feb 16, 2011 4:12 am
- Forum: The Library: Information Desk and Educational Resources
- Topic: What favors orbit or collision of two planetoids ?
- Replies: 23
- Views: 1396
What favors orbit or collision of two planetoids ?
Assume that two sizable planetoids are in similar orbits traveling in the same direction. Assume that one is 1/4 the size of the other in mass. Three possible scenarios could possibly occur. One is a collision between the two bodies; another is the ejection of one or both from their orbital region; ...
- Tue Feb 15, 2011 6:54 pm
- Forum: Classroom: Introductory Astronomy
- Topic: Lecture 08: Jupiter & Uranus
- Replies: 8
- Views: 87898
Re: Lecture 08: Jupiter & Uranus
Yes, I should have checked Wikepedia first. It is difficult to believe that radiogenic and tidal heating could have supplied enough energy for about 4 billion years. I wonder if there is an estimated radiogenic heating table for temperatures vs. core size vs. mantle thickness ? Your reference mentio...