The second planet of DM+19 279 is a garden world utterly unlike any other in the Archipelago. Persephone is a world tipped on its side: its rotation axis lies almost in the plane of its orbit (the axial tilt is actually 87°). This extreme axial tilt produces the most extreme seasons of any known world.
When the axis points towards the sun, one pole is in continuous daylight and the other in unending night. A quarter of a year later the axis is tangential to the direction of the sun and the poles are in permanent twilight. A further quarter-year and the initially cold and dark pole is in its Day and the other is in Night. For the polar regions, then, a year and a Day are the same, a long cycle from Dawn to Noon to Dusk to Midnight and then once more to Dawn.
From the equator things look very different. During Tangential days and nights pass as they would on Earth or most other colonised worlds; this is the equatorial summer. By Radial the days and nights have faded into the long twilight of winter. Each long polar Day thus corresponds to two cycles of equatorial summer and winter.
The temperature of poles varies from frozen and lifeless at Midnight, through conditions like those of the Terran arctic at Dawn and Dusk, through to the blazing heat of Noon. With these changes in temperature the icecaps oscillate back and forth. At Twilight the two poles have equal coverings of ice, whereas at Noon the ice coverage falls to nothing, leaving the pole a baking wasteland. The seasonal variation in temperature on the equator, though much less severe than for the poles, is still equivalent to moving from Earth's equator (in summer) to its poles (in winter).
In addition to the temperature variation, there are also massive changes in the pattern of atmospheric and oceanic circulation. At Tangential the global climate is generally Earth-like.