stellar occultation The dimming of starlight produced when a solar system object such as a planet, moon, or ring, passes directly in front of a star.
Stellar Occultation - The obstruction of the light from a star when a solar system body passes between the star and the observer ...
Stellar occultations have proved to be powerful tools to both measure sizes - at km-level accuracy, i.e. a factor ten better than what is feasible with other techniques - and detect very tenuous atmosphere - at microbar levels or less.
Two stellar occultations by Psyche have been observed (from Mexico on March 22, 2002, and another on May 16, 2002). Lightcurve variations indicate a non-spherical body, consistent with the lightcurve and radar results.
Aspects ...
PPS/UVS stellar occultation geometry (QuickTime (MOV) format, 1.3 Mbytes).
This animation illustrates the view from Voyager 2 during the occultation of the star sigma Sgr by Uranus' ring system.
The only techniques that measure the diameter directly (i.e., without having to model the actual observations) are those of stellar occultation and direct imaging using either advanced instruments on Earth (e.g.
Evidence that the rings are incomplete first arose in the mid-1980s, when stellar occultation were found to occasionally show an extra "blink" just before or after the planet occulted the star.
Following the successful detection of rings around Uranus in 1977, similar attempts were made to use stellar occultations to find rings around Neptune. These met with limited success in the mid-1980s.
The PDS Rings node has a new, preliminary data set of Saturn ring radial profiles derived from UVIS stellar occultation data. The data include ring radial profiles at 1 and 10 km resolution from more than 50 UVIS stellar occultations.
The radius can be estimated by measuring the duration of a stellar occultation from several observatories. Several observatories are needed, since otherwise it is unknown which part of the circular shadow was observed.
Study the radial structure of Saturn's rings by means of stellar occultations;
Study surface ices and tenuous atmospheres associated with the icy satellites.
Harold Reitsema is now usually credited with the discovery of Larissa by ground-based stellar occultation observations. The first (and so far only) images of it were obtained by Voyager 2.
To measure a distant planet like Pluto, astronomers look for "stellar occultations," when starlight passes through a planet's atmosphere.
Like the PFS instrument, SPICAM will also measure the composition of the Martian atmosphere but in smaller volumes. It will also use the technique of stellar occultation to measure the vertical profiles of carbon dioxide, temperature, ozone, ...
c Measured relative to the Earth. d A temporary atmosphere is suspected but has not yet been directly observed by stellar occultation.
1977 - James Elliot discovers the rings of Uranus during a stellar occultation experiment on the Kuiper Airborne Observatory
1978 - James Christy discovers Charon ...
 See also: Occultation, Satellite, Solar, Earth, Light
|
