BAS Observer March 2018

12 BAS OBSERVER The sky in March by Peter Allison D uring March the outer arms of our Milky Way Galaxy, in particular the Orion Spur and Perseus Arm, will be stretched diagonally across the sky in the early evening from south-east to north-west. The constellation Carina will be well placed on the meridian for great viewing. Dark-sky nights The best Moon-free nights for observing in March are from around 10th–19th March. After the 19th the Moon sets a little later each evening and interferes with early-evening observing. BEST DARK-SKY OBSERVING DATES FOR MARCH Alignment stars In March there are two very bright stars high in the sky that make good alignment stars. Look for Sirius, the brightest star in the sky, and Canopus, the second brightest. These make good alignment stars, are reasonably widely separated and very bright, and are difficult to mistake for another star. Canis Major Alignment stars: Canopus Sirius From about 10th March the Moon rises after midnight, providing some hours of dark sky. From about 19th March the Moon sets later and later each evening and eats into observing time.