As part of that Black Friday imaging blitz, I took a look at Uranus. In contrast to a set of images I took some eight years ago (see below), Uranus is now experiencing an equinox--its equator is now pointing towards the inner Solar System. You might remember that in contrast to the rest of the planets, Uranus and its satellites are tilted nearly ninety degrees off of the ecliptic, leaving each hemisphere to experience 21 year long summer and winters. The long slumber of cold is over for one pole and the light is fading for the other. And, since the moons' orbit in the plane of the Uranian equator, they mutually transit and occult each other for a time period during the equinox. As we orbit quickly in the warm inner solar system the plane of the satellites appears to wobble back and forth from Earth's motion. The period of mutual events is coming to a close, with only three left, and the seasons will become definitive on Uranus.
Uranus and three of its satellites: Ariel, Titania, and Oberon. 88x5second exposures. Click to enlarge.
Satellites identified via the Solar System Simulator.
A series of images taken long ago on a 382x240 pixel CCD!. Click to enlarge.