The brightest star in Piscis Austrinus is Fomalhaut. Images made by the Atacama Large Millimeter/submillimeter Array (ALMA) in 2012 revealed a narrow dusty ring probably constrained by a pair of unseen planets.

Piscis Austrinus, the Southern Fish, is high overhead for southern hemisphere observers at present. It's a challenge to discern the 'fish' shape but its brightest star, Fomalhaut, is easily seen with the naked eye.

The Cosmic Background Explorer (COBE) satellite was launched 25 years ago on 18 September, 1989. It showed that the cosmic microwave background, the cold afterglow of the Big Bang, was not completely uniform.

Comets like C67P/Churyumov-Gerasimenko formed in the frozen outer regions of the solar system. Virtually unchanged for over 4.5 billion years they provide clues about the formation of the solar system.

If all goes to plan the Rosetta spacecraft will release its comet lander Philae just after 8pm (AEDT) tonight. Philae will hopefully make the first ever landing on a comet (67P/Churyumov-Gerasimenko) in the early morning hours of Thursday November 13 AEDT. Follow the ESA landing webcast.

The brick building under Harley Wood's dome was demolished in 1986. The copper dome and Melbourne astrograph were intended by Macquarie University to continue their scientific work. However, this never came to be.

Harley Wood was the NSW Government Astronomer from 1943 to 1974. The dome he constructed was removed in 1986. The dome and Melbourne astrograph (and many other items) were rescued by Alan Vaughan and Macquarie University.

Emergence of a Great Sunspot AR12192. Sketch and copyright Harry Roberts ©, all rights reserved. What is it that causes some spots to grow very large? All are shaped by magnetic fields – stronger fields make bigger darker spots – but is this the sole reason?

Harley Wood's dome has just returned to Sydney Observatory after a 28 years absence. It was built in 1952 to house the Melbourne astrograph, a photographic telescope. It is now part of our new East dome which sits on the same site as Wood's original dome.

This has been the most exciting week in the life of Sydney Observatory for decades! The historic Astrograph dome arrived in the wee hours of the morning on Tuesday 4 November, and was then seated on top of the new building  on Thursday 6 November.

Having located Pegasus, the Winged Horse, on Melbourne Cup day now try looking for the Andromeda galaxy - the next closest large spiral galaxy. It is the fuzzy oval below the word 'Andromeda' in Tuesday's cosmobite.