Comments on: Highest res images of Iapetus yet! http://blogs.discovermagazine.com/badastronomy/2007/09/10/highest-res-images-of-iapetus-yet/ I am an astronomer, writer, and skeptic. I likes reality the way it is, and I aims to keep it that way. My real name is Phil Plait, and I run the Bad Astronomy blog. Mon, 09 Nov 2009 06:25:47 -0600 http://wordpress.org/?v=2.8.4 hourly 1 By: Spikey http://blogs.discovermagazine.com/badastronomy/2007/09/10/highest-res-images-of-iapetus-yet/comment-page-1/#comment-173608 Spikey Sat, 11 Apr 2009 11:31:32 +0000 http://blogs.discovermagazine.com/badastronomy/2007/09/10/highest-res-images-of-iapetus-yet/#comment-173608 It's always amusing to me just how fast and rabid the disinfo agents jump on any otherworldly information, regardless of where it is or what it is. Just a bit of advice to 'real' members of the public. Make up your own minds, use your brain and seek out your own data. Do not be swayed one way or the other and this or any other subject. The one's who shout the loudest, often have the most to hide. Well, their 'employers and masters' do at least. Read all you can, look with a critical eye. spikey. It’s always amusing to me just how fast and rabid the disinfo agents jump on any otherworldly information, regardless of where it is or what it is.

Just a bit of advice to ‘real’ members of the public.

Make up your own minds, use your brain and seek out your own data. Do not be swayed one way or the other and this or any other subject.

The one’s who shout the loudest, often have the most to hide. Well, their ‘employers and masters’ do at least.

Read all you can, look with a critical eye.

spikey.

]]> By: j http://blogs.discovermagazine.com/badastronomy/2007/09/10/highest-res-images-of-iapetus-yet/comment-page-1/#comment-48010 j Fri, 14 Sep 2007 01:43:12 +0000 http://blogs.discovermagazine.com/badastronomy/2007/09/10/highest-res-images-of-iapetus-yet/#comment-48010 Fantastic shots; thanks for pointing to this! Fantastic shots; thanks for pointing to this!

]]> By: KaiYeves http://blogs.discovermagazine.com/badastronomy/2007/09/10/highest-res-images-of-iapetus-yet/comment-page-1/#comment-48011 KaiYeves Wed, 12 Sep 2007 23:26:04 +0000 http://blogs.discovermagazine.com/badastronomy/2007/09/10/highest-res-images-of-iapetus-yet/#comment-48011 Great pictures. I'd love to meet Emily. Sorry if I was a little harsh back there, but ad hom is just a fancy word for name-calling, and I've been called a few too many names in this life. Great pictures. I’d love to meet Emily. Sorry if I was a little harsh back there, but ad hom is just a fancy word for name-calling, and I’ve been called a few too many names in this life.

]]> By: Regner Trampedach http://blogs.discovermagazine.com/badastronomy/2007/09/10/highest-res-images-of-iapetus-yet/comment-page-1/#comment-48015 Regner Trampedach Wed, 12 Sep 2007 03:02:29 +0000 http://blogs.discovermagazine.com/badastronomy/2007/09/10/highest-res-images-of-iapetus-yet/#comment-48015 Re: Crater chains. If we assume a case similar to the Shoemaker-Levy impact with Jupiter, we can calculate the distance between craters on Iapetus. We start off by making some simplifying assumptions and afterward test whether they change the conclusion. a) Both Jupiter and Iapetus are stationary in their orbit while getting pummeled. They still rotate, though. b) the impact occurs with zero impact parameter (head-on collision). According to tables found on the web, the average time between impacts of the last 10 fragments was about 5 hours. In that time the equator of the 718km radius Iapetus, rotating once every 79hours, has travelled about 12km or 1.7% of the radius of Iapetus. This is actually not too far from what is seen in the images. Considering that the fragment train of Shoemaker-Levy lengthened by a factor of 10 in a year, there is ample room for factors of 10 (up or down) in my result above. With impact close to the limb, the distance between the craters would be larger. Can we ignore the orbital velocities (one of my assumptions): From the length of the 23 fragment train around time of impact, 5,000,000km, and the 5hours between impacts, I get an approximate relative velocity of 45,000km/h, compared to the 1,900km/h orbital velocity of Iapetus. Jupiter and Saturn have orbital velocities of 47,000 and 35,000km/h, respectively, which means they can't be ignored. On the other hand first assumption would be that they are randomly oriented with respect to the impactor, in which case you would just get a larger spread in the result above - and, of course, many cases where many or most fragments would miss the "target". Thanks for a great post, Phil & Emily. Cheers, Regner Re: Crater chains.
If we assume a case similar to the Shoemaker-Levy impact with Jupiter, we can calculate the distance between craters on Iapetus. We start off by making some
simplifying assumptions and afterward test whether they change the conclusion.
a) Both Jupiter and Iapetus are stationary in their orbit while getting pummeled.
They still rotate, though. b) the impact occurs with zero impact parameter (head-on collision).
According to tables found on the web, the average time between impacts of the
last 10 fragments was about 5 hours. In that time the equator
of the 718km radius Iapetus, rotating once every 79hours, has travelled about
12km or 1.7% of the radius of Iapetus. This is actually not too far from what is
seen in the images. Considering that the fragment train of Shoemaker-Levy
lengthened by a factor of 10 in a year, there is ample room for factors of 10 (up or
down) in my result above. With impact close to the limb, the distance between the
craters would be larger.
Can we ignore the orbital velocities (one of my assumptions): From the length
of the 23 fragment train around time of impact, 5,000,000km, and the 5hours
between impacts, I get an approximate relative velocity of 45,000km/h, compared to the
1,900km/h orbital velocity of Iapetus. Jupiter and Saturn have orbital velocities
of 47,000 and 35,000km/h, respectively, which means they can’t be ignored. On
the other hand first assumption would be that they are randomly oriented with
respect to the impactor, in which case you would just get a larger spread in the
result above – and, of course, many cases where many or most fragments would
miss the “target”.
Thanks for a great post, Phil & Emily.
Cheers, Regner

]]> By: JanieBelle http://blogs.discovermagazine.com/badastronomy/2007/09/10/highest-res-images-of-iapetus-yet/comment-page-1/#comment-48018 JanieBelle Tue, 11 Sep 2007 23:51:49 +0000 http://blogs.discovermagazine.com/badastronomy/2007/09/10/highest-res-images-of-iapetus-yet/#comment-48018 Hoagland: <blockquote>However, that this geometry is not some new form of internal geological control -- modulated by the planetary Hyperdimensional Physics we’ve found operating on other planets – also seems clear; neither “ring” lies anywhere near the infamous 19.5-degree “upwelling latitude” controlled by internal “tetrahedral” forces we see operating on other planets and their satellites. Yet, the placement of both “ring features,” 120 degrees apart, is obviously conveying the same “tetrahedral message” left behind in other artificial ruins we’ve explored across the solar system ….</blockquote> Crap. I totally missed that in <em>Science</em>. Something that big, you'd think CNN would have said something. Darn mainstream media. Just can't trust 'em fer nuthin'. Kisses Hoagland:

However, that this geometry is not some new form of internal geological control — modulated by the planetary Hyperdimensional Physics we’ve found operating on other planets – also seems clear; neither “ring” lies anywhere near the infamous 19.5-degree “upwelling latitude” controlled by internal “tetrahedral” forces we see operating on other planets and their satellites. Yet, the placement of both “ring features,” 120 degrees apart, is obviously conveying the same “tetrahedral message” left behind in other artificial ruins we’ve explored across the solar system ….

Crap. I totally missed that in Science. Something that big, you’d think CNN would have said something.

Darn mainstream media. Just can’t trust ‘em fer nuthin’.

Kisses

]]> By: Keith Harwood http://blogs.discovermagazine.com/badastronomy/2007/09/10/highest-res-images-of-iapetus-yet/comment-page-1/#comment-48017 Keith Harwood Tue, 11 Sep 2007 23:33:43 +0000 http://blogs.discovermagazine.com/badastronomy/2007/09/10/highest-res-images-of-iapetus-yet/#comment-48017 It's a cannon ball! Last night the ABC (Australian Broadcasting Commission) showed an episode of TimeTeam where, among other things, they showed the casting of a cannon ball. It was identical to Iapetus. Mold mark and all. Mind you, it wasn't as big, but when you have only three days to do it in, you can't get too ambitious. It’s a cannon ball! Last night the ABC (Australian Broadcasting Commission) showed an episode of TimeTeam where, among other things, they showed the casting of a cannon ball. It was identical to Iapetus. Mold mark and all. Mind you, it wasn’t as big, but when you have only three days to do it in, you can’t get too ambitious.

]]> By: Troy http://blogs.discovermagazine.com/badastronomy/2007/09/10/highest-res-images-of-iapetus-yet/comment-page-1/#comment-48016 Troy Tue, 11 Sep 2007 23:08:33 +0000 http://blogs.discovermagazine.com/badastronomy/2007/09/10/highest-res-images-of-iapetus-yet/#comment-48016 That belly band would be great for a moon sized game of "Capture the Flag". That belly band would be great for a moon sized game of “Capture the Flag”.

]]>