While excitement among planetary observers is growing for the best views of Mars for 15 years (Martian dust storms permitting) in late July, there’s still one prior planetary treat: the opposition of Saturn on 27 June, which coincides with a close lunar conjunction. We show you what to look for in and around the Saturnian system.
A thrilling ride is about to begin for NASA’s Cassini spacecraft. Engineers have been pumping up the probe’s orbit around Saturn this year to increase its tilt with respect to the planet’s equator and rings. And on 30 November, following a gravitational nudge from Saturn’s moon Titan, Cassini will enter the first phase of the mission’s dramatic endgame.
The shadow of Saturn’s globe on the rings, which stretched across all of the rings earlier in the Cassini spacecraft’s mission, now barely makes it past the Cassini Division. The changing length of the globe’s shadow marks the passing of the seasons on Saturn. As the planet nears its northern-hemisphere solstice in May 2017, the shadow will get even shorter.
You might think that, in the rings of Saturn, more opaque areas contain a greater concentration of material than places where the rings seem more transparent. But this intuition does not always apply, according to a recent study of the rings using data from NASA’s Cassini mission. The research also suggests that the planet’s brightest B ring could be a few hundred million years old instead of a few billion.
Janus and Tethys demonstrate the main difference between small moons and large ones; it’s all about their shape. Moons like Tethys are large enough that their own gravity is sufficient to overcome the material strength of the substances they are made of and mould them into spherical shapes, but small moons like Janus are not massive enough for their gravity to form them into a sphere.