A beautiful, shining comet flying through the sky is a rare thing. But this week it's not even going to be the rarest.
Friday night wll in fact see that comet – a green, shining light followed by a purple trail, known as 45P/Honda-Mrkos-Pajdušáková – joined by a bright, shining full "snow moon" and a lunar eclipse, all at the same time.
Starting early Friday evening, a penumbral lunar eclipse will begin. That means that the sun, moon and earth all line up and cast a strange effect on the moon.
Unlike a total eclipse – where the earth blots out all light on the moon, casting it into a dark shadow – this week's will be more subtle. Our closest neighbour will gradually darken as the three objects move around.
The eclipse will be best seen in Europe or Africa and will begin no Friday evening. It might not even be noticeable without intently looking, since its effects are so subtle.
But the moon itself will be remarkable, even if you can't see the eclipse. Dubbed the "snow moon" – because February is the snowiest month – it will be full and bright and the sky will be lit up bright through Friday night.
But probably most notable is the comet itself, which will shoot past close enough to be visible from earth. The comet is a bright emerald green, probably a result of the evaporation of diatomic carbon as it flies through space. And it is marked out by a bright purple tail – but it might actually have lost that since it last flew past us, astronomers say, probably the result of a brush with Venus that led it to burn off the ice core that creates it.
None of the events will be quite as spectacular as the huge total solar eclipse that will be visible across the US on 21 August. That will be the first time such an event has happened in 99 years, and may see the biggest movement of people ever.
