What's Up in Space
This Weekend’s Night Sky (25 - 26 April 2015)
The Moon is at first quarter this weekend and will be easily visible in our late afternoon and early evening skies. The name first quarter can be a little confusing because we can actually see half of the Moon lit up at this time, with the other half is in darkness. The name first quarter actually refers to the fact that the Moon has completed the first quarter of its journey around the Earth.
This is a good time for observing our nearest neighbour in space. Not only is it well positioned in the sky at a convenient time of night, but the angle of the Sun highlights the features of the lunar surface.
At full moon the Sun’s light shines straight down on to the part of the Moon we can see and the Moon looks very bright and washed out. At first quarter, however, the Sun’s light hits the part of the Moon facing towards us at an angle. The closer you look to the terminator – the line between the lit and unlit side - the more acute the angle at which the Sun’s light hits, much like at sunrise or sunset here on Earth. This light is more spread out across the surface creating long shadows from mountains and crater walls and making these features much easier to spot. Even with the naked eye you should be able to see a good amount of detail, but with binoculars or a small telescope the view is even better.
Take a look at http://astredu.nz/index.php/right-now/current-mmoon for some good southern hemisphere view Moon maps to help you identify what you’re seeing.