Probing Titan's atmosphere by stellar occultation
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.
- Publication:
-
Nature
- Pub Date:
- January 1990
- DOI:
- 10.1038/343350a0
- Bibcode:
- 1990Natur.343..350S
- Keywords:
-
- Atmospheric Physics;
- Satellite Atmospheres;
- Stellar Occultation;
- Titan;
- Light Curve;
- Satellite Sounding;
- Stratosphere;
- Lunar and Planetary Exploration; Satellites of Saturn;
- SATURN;
- TITAN;
- SATELLITES;
- ASTRONOMY;
- OCCULTATIONS;
- ATMOSPHERE;
- ALTITUDE;
- STRATOSPHERE;
- PHYSICAL PROPERTIES;
- EARTH-BASED OBSERVATIONS;
- ANALYSIS;
- LIGHTCURVES;
- TECHNIQUES;
- TEMPERATURE;
- OBLIQUITY