Abstract
WE report results from the first stellar occultation by Titan ever observed. As predicted by Wasserman1, on 3 July 1989 the bright star 28 Sagittarii (visual magnitude, V ≈ 5.5), passed behind Saturn's giant moon ( V ≈ 8.3), which is the only body in the Solar System that, like the Earth, has a dense, nitrogen-rich atmosphere2. The event, visible from Europe, North Africa and the Middle East, allowed us to probe Titan's atmosphere in an altitude range of ∼ 250–500 km (a pressure range of ∼250-1 μbar), where until now, there has been an 'information gap' between infrared and ultraviolet Voyager observations3–5. We also detected a central flash as the centre of Titan's shadow passed at a few tens of kilometres from Paris. This central flash allows us to estimate a finite oblateness of Titan's stratosphere, which could arise from a super-rotation of Titan's atmosphere.
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Sicardy, B., Brahic, A., Ferrari, C. et al. Probing Titan's atmosphere by stellar occultation. Nature 343, 350–353 (1990). https://doi.org/10.1038/343350a0
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DOI: https://doi.org/10.1038/343350a0
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