Starwatch: a blue moon in Virgo

Starwatch 26 Mar 2018 blue moon

The month ends this week with a blue moon. Last week was the equinox, when day and night are of equal length. It took place on 20 March. From now on in the northern hemisphere, spring has begun and the days will get progressively longer. In the southern hemisphere, the seasons are reversed. This equinox marked the beginning of autumn and progressively shorter days. On 31 March, the Moon is full. It rises as the Sun sets and takes the whole night to cross the sky, setting as the new dawn begins. This is the second full moon of the month, the first happened on 2 March. The second full moon of a calendar month is commonly referred to as a blue moon, although it is highly debated whether this is the correct usage of the term. The Moon sits squarely in the body of Virgo at 21:00 GMT on 31 March, allowing this faint constellation to be traced out around it.