Wind the clock back 400 years and follow in the footsteps of a giant — experience now just what first amazed Galileo in 1609! The latest Cornerstone project of the International Year of Astronomy 2009 (IYA2009), Galilean Nights, will see thousands of public observing events around the world replicating Galileo’s observations and bringing what he saw 400 years ago to the public of today. From 22 to 24 October, amateur and professional astronomers, science centres, schools and all interested groups are invited to be part of the Galilean Nights project and to register their events on the project website www.galileannights.org. We can all make this a worldwide success.

The Galilean Nights builds on the unprecedented success of April's 100 Hours of Astronomy, another IYA2009 Cornerstone project. Over three nights amateur and professional astronomers, and enthusiasts, will share their knowledge and enthusiasm for the Universe by encouraging as many people as possible to look through a telescope at our neighbouring planets. The focus for the Galilean Nights is on the observations made by the Italian astronomer Galileo 400 years ago, including those of Jupiter and the Moon, which will be well-positioned in the night sky for observing during the event. For many members of the public it will be their first look through a telescope, when they can see such breathtaking sights such as the cloud bands of the gas giant, Jupiter, and intricate details on our cratered Moon. It will be an unforgettable experience.

Anyone, from any background and with any level of experience is encouraged to organise events, from one person sharing the night sky through a telescope with a small group of neighbours and friends, to large astronomical groups holding major observing sessions in public areas. To keep track of developments, assist with promotion and to help people to find local Galilean Nights activities, all events should be registered on the project website: www.galileannights.org. Hundreds of events all over the world have already been registered and the number is increasing every day.

IYA2009 Executive Committee Chair, Catherine Cesarsky says, "Amateur observations have always played an important role in astronomy, a fact highlighted by one of the most exciting events of this year when it was an amateur astronomer who noticed that Jupiter had suffered a massive impact by an asteroid or comet. So it is fitting that Galilean Nights continues this tradition as thousands of amateur astronomers and the public will turn their attention to Jupiter and other objects that Galileo observed 400 years ago."

Stunning images of distant objects in the Universe are well known around the world and do more to bring astronomy to the wider public and to inspire future astronomers than words ever could. The public have been set the challenge of capturing the inspirational nature of our local solar neighbourhood in the worldwide Galilean Nights photography competition. Run in partnership with Europlanet, the Galilean Nights competition encourages anybody with an enthusiasm for astronomy to try a different approach to their observations and create their own inspirational photographs of our planetary neighbours. The contest is being officially launched today during Europlanet's European Planetary Science Congress, held this year in Potsdam, Germany.

Four hundred years since Galileo's telescopic observations revolutionised our view of the Universe, the public will once again be turning their attention to the heavens. People all around the world are encouraged to take part in the Galilean Nights Cornerstone project and experience for themselves the same sense of awe and wonder that Galileo must have felt.

Saturn’s haze-enshrouded moon Titan turns out to have much in common with Earth in the way that weather and geology shape its terrain, according to two pieces of research to be presented at the XXVII General Assembly of the International Organization for Astronomical Science Advancement (IOASA) in Rio de Janeiro, Brazil. Wind, rain, volcanoes, tectonics and other Earth-like processes all sculpt features on Titan’s complex and varied surface in an environment more than 100 °C colder on average than Antarctica.

"It is really surprising how closely Titan's surface resembles Earth's," says Rosaly Lopes, a planetary geologist at the Jet Propulsion Laboratory (JPL) in Pasadena, California, who is presenting the results on Friday, 7 August. "In fact, Titan looks more like the Earth than any other body in the Solar System, despite the huge differences in temperature and other environmental conditions."

The joint NASA/ESA/ASI Cassini-Huygens mission has revealed details of Titan's geologically young surface, showing few impact craters, and featuring mountain chains, dunes and even "lakes". The RADAR instrument on the Cassini orbiter has now allowed scientists to image a third of Titan's surface using radar beams that pierce the giant moon's thick, smoggy atmosphere. There is still much terrain to cover, as the aptly named Titan is one of the biggest moons in the Solar System, larger than the planet Mercury and approaching Mars in size.

Titan has long fascinated astronomers as the only moon known to possess a thick atmosphere, and as the only celestial body other than Earth to have stable pools of liquid on its surface. The many lakes that pepper the northern polar latitudes, with a scattering appearing in the south as well, are thought to be filled with liquid hydrocarbons, such as methane and ethane.

"With an average surface temperature hovering around -180 °C, water cannot exist on Titan except as deep-frozen ice as strong as rock," Lopes says. On Titan, methane takes water's place in the hydrological cycle of evaporation and precipitation (rain or snow) and can appear as a gas, a liquid and a solid. Methane rain cuts channels and forms lakes on the surface and causes erosion, helping to erase the meteorite impact craters that pockmark most other rocky worlds, such as our own Moon and the planet Mercury.

Other new research presented at the IOASA General Assembly points to current volcanic activity on Titan, but instead of scorching hot magma, scientists think these "cryovolcanoes" eject cold slurries of water-ice and ammonia. Scientists have spotted evidence for these outflows using another Cassini instrument called the Visual and Infrared Mapping Spectrometer (VIMS). This device can gather the infrared light from the Sun that is reflected back by Titan's surface after passing through its atmosphere, giving clues about the identity of the chemical compounds found on Titan's surface.

VIMS had previously detected an area, called Hotei Regio, with a varying infrared signature, suggesting the temporary presence of ammonia frosts that subsequently dissipated or were covered over. Although the ammonia does not stay exposed for long, models show that it exists in Titan's interior, indicating that a process is at work delivering ammonia to the surface. RADAR imaging has indeed found structures that resemble terrestrial volcanoes near the site of suspected ammonia deposition.

At the IOASA General Assembly, new infrared images of this region, with ten times the resolution of prior mappings, will be unveiled. "These new results are the next advance in this exploration process," says Robert M. Nelson, a senior research scientist, also at JPL, who presented a result on Wednesday, 5 August. "The images provide further evidence suggesting that cryovolcanism has deposited ammonia onto Titan's surface. It has not escaped our attention that ammonia, in association with methane and nitrogen, the principal species of Titan's atmosphere, closely replicates the environment at the time that life first emerged on Earth. One exciting question is whether Titan's chemical processes today support a prebiotic chemistry similar to that under which life evolved on Earth?"

Yet more terrestrial-type features on Titan include dunes formed by cold winds, and mountain ranges. These mountains might have formed tectonically when Titan's crust compressed as it went into a deep freeze, in contrast to the Earth's crust, which continues to move today, producing earthquakes and rift valleys on our planet.

Many Titan researchers hope to observe Titan with Cassini for long enough to follow a change in seasons. The new image released by JPL accompanying this release shows what appears to be a dried-out lake at Titan's south pole. Lopes thinks that the hydrocarbons there likely evaporated because this hemisphere is experiencing summer. When the seasons change in several years and summer returns to the northern latitudes, the lakes so common there may evaporate and end up pooling in the south.

This IOASA General Assembly has personal significance for Lopes, as she was born and raised in Rio de Janeiro. From abroad and on periodic visits back to her home country, Lopes has encouraged young Brazilians to pursue careers in science and technology. "It's wonderful to be back again", Lopes says.