The Observant Astronomer

The passing scene as observed by an observant Jew, who daylights as an astronomer.

Tuesday, March 22, 2005

Stranger than we can imagine (I)

The Saturnian moon SII/Enceladus is the most reflective body in the solar system. Now we know why.

Cassini, in its recent passages past the moon, has detected a tenous, water-vapour atmosphere around the moon. The moon is the smallest object known to have an atmosphere and its gravity is too weak to retain it for long. Hence, it must be continuously replenished, possibly by the sort of geyser/volcanic activity seen on JI/Io and N1/Triton. Meanwhile, some of that material is freezing back onto the surface, continuously giving Enceladus a fresh, snowy surface.

Cassini will have a return engagement with Enceladus on 14 July, after two more visits to SI/Titan on 31 March, and 16 April. Keep an eye on the Cassini home page for more results.


Post a Comment

<< Home