Starship Asterisk*

Do objects captured in Trojan orbits rotate relative to the objects they lead/follow? Is the dynamic such that they're gravitationally locked to their parent bodies? Is there a practical limit to the size of a Trojan object?

[float=left][img3=""]http://upload.wikimedia.org/wikipedia/commons/thumb/e/e5/CrosseyedMCC.jpg/640px-CrosseyedMCC.jpg[/img3][/float][quote="Chris Peterson"][quote="jsmunroe"]

Is there anyway you could do a "cross-eyed" stereography for those of us who don't have the special glasses? Most of the time, I do this myself, but the images are scaled differently for this one. :([/quote]
I find anaglyphs to be an entirely unsatisfactory way of viewing 3D images, so for anything interesting, the first thing I do myself is construct a proper stereo pair. Here's mine for this set of images:[/quote]

[quote="jsmunroe"]Is there anyway you could do a "cross-eyed" stereography for those of us who don't have the special glasses? That is, put the images next to eachother in such a way that they one can either cross-their eyes or stare parallel at the images in order see the three dimensional image? Most of the time, I do this myself, but the images are scaled differently for this one. :([/quote]
I find anaglyphs to be an entirely unsatisfactory way of viewing 3D images, so for anything interesting, the first thing I do myself is construct a proper stereo pair. Here's mine for this set of images:

[attachment=0]helene3d_crossed.jpg[/attachment]

Is there anyway you could do a "cross-eyed" stereography for those of us who don't have the special glasses? That is, put the images next to eachother in such a way that they one can either cross-their eyes or stare parallel at the images in order see the three dimensional image? Most of the time, I do this myself, but the images are scaled differently for this one. :(

Is Helene made up of water ice? Is it chunks of ice that appear to flow into the "crater"-like shapes to form the gullies?

So, if either of these ice moons were orbiting the Sun instead of Saturn, they might be comets?

[quote="orin stepanek"]

I thought this picture looked familar! 8-) http://apod.nasa.gov/apod/ap110623.html[/quote]
http://asterisk.apod.com/viewtopic.php?f=9&t=28410

http://apod.nasa.gov/apod/ap120502.html
http://asterisk.apod.com/discuss_apod.php?date=120502

I thought this picture looked familar! 8-) http://apod.nasa.gov/apod/ap110623.html

http://asterisk.apod.com/discuss_apod.php?date=110623

[quote="APOD Robot"]... about 36 by 32 by 30 kilometers ...
[The image] shows part of the [b]Saturn-facing[/b] hemisphere of Helene ...[/quote]
[url=http://en.wikipedia.org/wiki/Helene_(moon)]Wikipedia[/url] lists 43.4×38.2×26 km from a P.C. Thomas study (2010, Cornell University) on the "Sizes, shapes, and derived properties of the saturnian satellites after the Cassini nominal mission".
[quote="P.C. Thomas"]Table 3
Properties of irregularly-shaped saturnian satellites.
Moon: Helene
Radius "a" (Saturn-facing): 21.7 ± 0.5 km
Radius "b" (orbit-facing): 19.1 ± 0.3 km
Radius "c" (polar radius): 13.0 ± 0.3 km
Mean radius (radius of a sphere of same volume): 17.6 ± 0.4 km[/quote]
The 3D effect is huge. To me, in this image it looks like the depth is much more that the width, like the small profile angle on a football. But the numbers seem to suggest that we’re looking at the biggest possible profile, namely the Saturn-facing side.

[url=http://apod.nasa.gov/apod/ap130105.html][img]http://apod.nasa.gov/apod/calendar/S_130105.jpg[/img] [size=150]Stereo Helene[/size][/url]

[b] Explanation: [/b] Get out your [url=http://photojournal.jpl.nasa.gov/Help/VendorList.html#Glasses]red/blue glasses[/url] and float next to Helene, small, icy moon of Saturn. [url=http://solarsystem.jpl.nasa.gov/planets/profile.cfm?Object=Sat_Helene]Appropriately named, Helene[/url] is one of four known Trojan moons, so called because it orbits at a [url=http://math.ucr.edu/home/baez/lagrange.html]Lagrange point[/url]. A Lagrange point is a gravitationally stable position near two massive bodies, in this case [url=http://apod.nasa.gov/apod/ap051231.html]Saturn and larger moon Dione[/url]. In fact, irregularly shaped ( about 36 by 32 by 30 kilometers) Helene orbits at Dione's leading Lagrange point while brotherly ice moon Polydeuces follows at Dione's trailing Lagrange point. [url=http://space-3d-images.blogspot.com/2011/06/helene-3d-cassini-cattura-la-regina-del.html]The sharp stereo anaglyph[/url] was constructed from two [url=http://saturn.jpl.nasa.gov/photos/raw/]Cassini images[/url] ([url=http://saturn.jpl.nasa.gov/photos/raw/rawimagedetails/index.cfm?imageID=239054]N00172886[/url], [url=http://saturn.jpl.nasa.gov/photos/raw/rawimagedetails/index.cfm?imageID=239060]N00172892[/url]) captured during [url=http://www.ciclops.org/view_event/157/Helene_Rev_149_Raw_Preview?js=1]a close flyby in 2011[/url]. It shows part of the Saturn-facing hemisphere of Helene mottled with craters and gully-like features.

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