Titan and Rhea

Rhea emerges after being occulted by the larger moon Titan.
Credit: NASA/JPL/Space Science Institute

I love this image for a few reasons.

First, of course, it’s beautiful. It looks like as if Rhea is poking through the atmosphere of Titan. What a sight to see with my own eyes… if only we have more than one moon…

Secondly is the different between the edge of the moons – it’s fuzzy for Titan but is sharp for Rhea. The fuzzy edge for Titan is due to its thick atmosphere, which is clearly visible here with high altitude detached haze layer. Rhea has no atmosphere thus the boundary is sharp.

Thirdly, the limb darkening effect is giving me a 3D feel of the whole scene.

Titan is the largest moon of Saturn and Rhea is the second largest. I know that the size difference between these largest and second largest moons is quite a lot (it’s about 3600 km after I looked up the figure), but I didn’t expect Rhea to be so small compared to Titan in the image. Then I realise my mistake… both of them are not at the same distance from Cassini, of course! Titan is about 1 million km from Cassini and Rhea is about 2.3 times as far.


~ by thChieh on December 30, 2009.

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