I was visiting the Tall Ships event in Dublin recently when I noticed something strange in the light blue daytime sky! Overlooking the River Liffey I could see something that looked like the Moon, but the Sun was still shining, so it couldn’t have been the Moon – or was Read more…
Once, in complete silence, a large boulder rolled down a slope on the central peak of the Moon’s Schiller crater. This rock is about 9m (30ft) across, meaning that it would fit neatly inside Armagh Planetarium’s 11 m wide Digital Theatre. The Moon’s surface has been to all intents and Read more…
Helene is a tiny moon of Saturn that shares an orbit with the much larger moon Dione. Helene reposes at a gravitationally stable position called a Lagrange point. Helene orbits Saturn ahead of Dione, and viewed from above the centres of Dione, Saturn and Helene form a vast equilateral triangle. Read more…
The peak at the centre of Tycho Crater on our Moon has been imaged by the Lunar Reconnaissance Orbiter spacecraft. Let’s take a look at this spectacular mountain of the Moon. One of the best-known lunar craters, Tycho is not especially large at some 85 km across. However it is Read more…
In March 2010 that superb but underappreciated probe Mars Express made a series of very close passes by the Martian moon Phobos. On one occasion it came as close as 107 km to the tiny world’s surface. The purpose of these encounters was to determine information on Phobos’ interior Read more…