Starwatch: a chance to bask in earthshine
This evening’s crescent moon brings with it a good chance of seeing earthshine. This is the faint glow that appears on the unlit portion of the moon’s disc. It is sometimes referred to as the old moon in the new moon’s arms because of the way the sunlit crescent appears to cradle the dimmer circle.
The cause of this faint light was debated for centuries until Leonardo Da Vinci wrote in his Codex Leicester of 1510 that our planet was acting like a mirror and reflecting sunlight onto the dark side of the moon.
Initially, Da Vinci thought it was Earth’s oceans that reflected the sunlight but we now know it is cloud cover. Earthshine can be seen for a few days before and after new moon, which this month took place on 15 February.
This month is unusual because it does not have a full moon. The last one took place on 31 January, and the next will be on 2 March.
