As The World Turns

Today is the autumnal equinox, when the Earth receives sunlight at its most direct angle relative to its equator and poles. As Earth orbits around the Sun over the course of a year, its axial tilt causes the angle of solar illumination to change – a predictable and regular change, but a change nonetheless. This…

Equinox Revisited

Here’s a beautiful color portrait of Saturn taken by Cassini during the planet’s 2009 spring equinox last August. Approximately every fifteen years Saturn is angled so that the light from the sun strikes it straight-on, causing the shadows cast by the rings to appear as a pencil-thin line along its equator. The Cassini spacecraft happened…

Saturn in the Spring

The Cassini Imaging Team has released this image, a stunning portrait of Saturn made from 75 separate wide-angle exposures taken during the ringed planet’s spring equinox on August 12, 2009. The specific angle of sunlight during the equinox makes the shadow of Saturn’s expansive rings appear as a pencil-thin line across the cloudtops at the…

Rings in Relief

This wide-angle view from Cassini, taken on August 16 (2009), shows an amazing amount of relief across the surface of Saturn’s A ring as well as a long shadow cast by the wake of the shepherd moon Daphnis within the Keeler gap. 4.3-mile-wide Daphnis, almost too small to be seen here, sculpts the edges of…

Dark Rings

The shadow of Saturn’s rings is reduced to a thin sliver running across the face of the planet in the upper part of this image taken on August 12, one day after its spring equinox. The rings appear dark in this image, since the sunlight is striking them edge-on and Cassini’s cameras are set so…

The Ghost and the Darkness

A spectral figure casts a long shadow as it travels along the path of Saturn’s F ring on August 7, 2009 in this image from the Cassini orbiter. Not a ghost per se but rather a clump of ring material, pulled upwards from the rest of the ring plane by what is perhaps a small…