IPB

Welcome Guest ( Log In | Register )

2 Pages V   1 2 >  
Reply to this topicStart new topic
Venus Radar Request, From Earth
Decepticon
post Mar 7 2006, 02:43 AM
Post #1


Senior Member
****

Group: Members
Posts: 1276
Joined: 25-November 04
Member No.: 114



I'm looking for earth based radar mapping of Venus.

I've had a hard time finding much. I clearly remember seeing images in books as a child.

Any help would be great!
Go to the top of the page
 
+Quote Post
JRehling
post Mar 7 2006, 02:59 AM
Post #2


Senior Member
****

Group: Members
Posts: 2530
Joined: 20-April 05
Member No.: 321



QUOTE (Decepticon @ Mar 6 2006, 06:43 PM) *
I'm looking for earth based radar mapping of Venus.

I've had a hard time finding much. I clearly remember seeing images in books as a child.

Any help would be great!


http://www.gps.caltech.edu/~margot/venus/aogbt.html

http://www.nrao.edu/pr/2001/gbtfirstsci/
(almost identical content to the first link)

http://www.nasm.si.edu/ceps/etp/venus/venusimg/P15.JPEG
Go to the top of the page
 
+Quote Post
Decepticon
post Mar 7 2006, 03:25 AM
Post #3


Senior Member
****

Group: Members
Posts: 1276
Joined: 25-November 04
Member No.: 114



WOW!

I didn't expect the images so clear!
Go to the top of the page
 
+Quote Post
JRehling
post Mar 7 2006, 06:20 AM
Post #4


Senior Member
****

Group: Members
Posts: 2530
Joined: 20-April 05
Member No.: 321



QUOTE (Decepticon @ Mar 6 2006, 07:25 PM) *
WOW!

I didn't expect the images so clear!


Compared to spacecraft flyby/orbiter standards... what terrestrial observations of Venus lack in proximity, they make up for in the size of the antennas. And those observations can be made when Venus is almost at conjunction, and thus considerably closer to the Earth than Venus or Mars ever is for a telescopic observation. Quite simply, radar observations of Venus are of considerably higher resolution than any other Earth-based observations of any planet could be.
Go to the top of the page
 
+Quote Post
edstrick
post Mar 7 2006, 08:58 AM
Post #5


Senior Member
****

Group: Members
Posts: 1870
Joined: 20-February 05
Member No.: 174



The only fly in this pudding is that there is a weird near-synchronicity between the rotation period of Venus and the position of inferior conjunctions with Earth. Very-Very nearly the same hemisphere of Venus faces Earth each conjunction! It's not quite exact, but it is improbably close. They've tried to see if the small tidal pull of Earth on Venus at inferior conjuction was more than vanishingly small and might explain this cooincidence, but it seems to be unlikely. The best idea I've heard so far is that the gods must be crazy.
Go to the top of the page
 
+Quote Post
helvick
post Mar 7 2006, 09:46 AM
Post #6


Dublin Correspondent
****

Group: Admin
Posts: 1799
Joined: 28-March 05
From: Celbridge, Ireland
Member No.: 220



QUOTE (edstrick @ Mar 7 2006, 08:58 AM) *
The best idea I've heard so far is that the gods must be crazy.

And are the same crazy Gods responsible for the very slow rotation of Venus? Or is there a plausible\likely explanation for it just happening that way?
Go to the top of the page
 
+Quote Post
edstrick
post Mar 7 2006, 10:57 AM
Post #7


Senior Member
****

Group: Members
Posts: 1870
Joined: 20-February 05
Member No.: 174



Last I heard they figure it's just coincidence.
Go to the top of the page
 
+Quote Post
Decepticon
post Mar 7 2006, 01:10 PM
Post #8


Senior Member
****

Group: Members
Posts: 1276
Joined: 25-November 04
Member No.: 114



The best one I've heard so far is "Venus was a Comet!" Straight from the wHoGland Funny Farm. biggrin.gif
Go to the top of the page
 
+Quote Post
Jeff7
post Mar 7 2006, 08:50 PM
Post #9


Member
***

Group: Members
Posts: 477
Joined: 2-March 05
Member No.: 180



Venus is made from people! Peeeoopllle!!!!!
Go to the top of the page
 
+Quote Post
Guest_AlexBlackwell_*
post Mar 7 2006, 09:02 PM
Post #10





Guests






QUOTE (helvick @ Mar 7 2006, 09:46 AM) *
And are the same crazy Gods responsible for the very slow rotation of Venus? Or is there a plausible\likely explanation for it just happening that way?

Correia and Laskar have published some interesting work on this.
Go to the top of the page
 
+Quote Post
Decepticon
post Mar 7 2006, 11:16 PM
Post #11


Senior Member
****

Group: Members
Posts: 1276
Joined: 25-November 04
Member No.: 114



I once heard a theory that a violent impact hit Venus against it's natural spin causing it to rotate the opposite way.

What ever it was it must have been a big bugger.
Go to the top of the page
 
+Quote Post
AndyG
post Mar 8 2006, 09:24 AM
Post #12


Member
***

Group: Members
Posts: 593
Joined: 20-April 05
Member No.: 279



QUOTE (Decepticon @ Mar 7 2006, 11:16 PM) *
I once heard a theory that a violent impact hit Venus against it's natural spin causing it to rotate the opposite way.

What ever it was it must have been a big bugger.

Shame it didn't end up with a lovely (and life-on-Earth-supporting?) Moon like ours.

Andy
Go to the top of the page
 
+Quote Post
ljk4-1
post Mar 8 2006, 02:59 PM
Post #13


Senior Member
****

Group: Members
Posts: 2454
Joined: 8-July 05
From: NGC 5907
Member No.: 430



QUOTE (AndyG @ Mar 8 2006, 04:24 AM) *
Shame it didn't end up with a lovely (and life-on-Earth-supporting?) Moon like ours.

Andy


I dunno - War of the Worlds could have happened coming from the
other direction.

Or in a parallel universe, it is the inhabitants of Venus who wonder
what might have been if only Earth weren't a barren wasteland.


--------------------
"After having some business dealings with men, I am occasionally chagrined,
and feel as if I had done some wrong, and it is hard to forget the ugly circumstance.
I see that such intercourse long continued would make one thoroughly prosaic, hard,
and coarse. But the longest intercourse with Nature, though in her rudest moods, does
not thus harden and make coarse. A hard, sensible man whom we liken to a rock is
indeed much harder than a rock. From hard, coarse, insensible men with whom I have
no sympathy, I go to commune with the rocks, whose hearts are comparatively soft."

- Henry David Thoreau, November 15, 1853

Go to the top of the page
 
+Quote Post
JRehling
post Mar 8 2006, 04:19 PM
Post #14


Senior Member
****

Group: Members
Posts: 2530
Joined: 20-April 05
Member No.: 321



QUOTE (AlexBlackwell @ Mar 7 2006, 01:02 PM) *
Correia and Laskar have published some interesting work on this.


I've tried about six of those links, and they are all dead.


QUOTE (JRehling @ Mar 8 2006, 08:10 AM) *
I've tried about six of those links, and they are all dead.


However, a summary/abstract appears here:
http://physicsweb.org/articles/news/05/6/6

The low inclination and extremely low angular momentum always made impact-based explanations unlikely. It's pretty hard to smash things together and get things to balance out that neatly. C&L's work seems to conclude that from first principles, that with an atmosphere that thick, the planet's rotation is going to be driven by the atmosphere. Presumably (what the abstract/summary doesn't say), the huge thermal input from the Sun is another part of the story. Saturn, Uranus, and Neptune have bigger atmospheres, but they don't have daysides lit by a Sun measuring a full degree in the sky -- they have two+ orders of magnitude less solar input.

I don't know if anyone has ever looked at this angle, but with Grinspoon, et al, proposing that Venus may have lacked those bright clouds for much of its history, it may have formerly had particulalry large thermal tides if it had an albedo as low as, say, Mars or Earth's continents. If you imagine an atmosphere sticking out tens of km (?) farther on the dayside than the nightside, that's a lot of friction working against rotation.
Go to the top of the page
 
+Quote Post
Guest_AlexBlackwell_*
post Mar 8 2006, 04:20 PM
Post #15





Guests






QUOTE (JRehling @ Mar 8 2006, 04:10 PM) *
I've tried about six of those links, and they are all dead.

Ouch. I know it worked back in 2002; in fact, I believe I referenced it over in Yahoo! planetary_sciences at the time biggrin.gif

Try Laskar's page, though I believe these may be preprints instead of the final versions that were on Corriea's page. If you need the the final versions, John, let me know.
Go to the top of the page
 
+Quote Post

2 Pages V   1 2 >
Reply to this topicStart new topic

 



RSS Lo-Fi Version Time is now: 19th March 2024 - 02:29 AM
RULES AND GUIDELINES
Please read the Forum Rules and Guidelines before posting.

IMAGE COPYRIGHT
Images posted on UnmannedSpaceflight.com may be copyrighted. Do not reproduce without permission. Read here for further information on space images and copyright.

OPINIONS AND MODERATION
Opinions expressed on UnmannedSpaceflight.com are those of the individual posters and do not necessarily reflect the opinions of UnmannedSpaceflight.com or The Planetary Society. The all-volunteer UnmannedSpaceflight.com moderation team is wholly independent of The Planetary Society. The Planetary Society has no influence over decisions made by the UnmannedSpaceflight.com moderators.
SUPPORT THE FORUM
Unmannedspaceflight.com is funded by the Planetary Society. Please consider supporting our work and many other projects by donating to the Society or becoming a member.