EarthSky, which by the way is a fantastic website for anyone who wants to get more out of the night sky that’s in great need of your support, has this to say about tonight’s supermoon, which will be the largest of 2019:
This year’s February presents the biggest full moon supermoon of 2019. From around the world, the moon will look plenty full to the eye on both February 18 and February 19 as it parades across the nighttime sky. It reaches the crest of its full phase on February 19 for much of the world. What’s a supermoon? It’s a popularized term for what astronomers call a perigean full moon. In other words, it’s a full moon near perigee, or closest to Earth for this month. This February 2019 full moon reaches its exact full phase closer to the time of perigee than any other full moon this year. Hence the year’s closest supermoon.
Will you be able to discern with your eye that this full moon is larger than an ordinary full moon? Experienced observers say they can do it, but – for most of us – the difference is too small for the eye to notice.
…here are other factors that make a supermoon special. For example, if you look outside tonight – assuming your sky is clear – you might be able to discern with your eye that the landscape is more brightly lit than usual by moonlight. Supermoons are substantially brighter than ordinary full moons.
Also, the moon’s gravity affects earthly tides, and a supermoon – full moon closest to Earth – pulls harder on Earth’s oceans than an ordinary full moon. That’s why supermoons create higher-than usual tides, which tend to come a day or two after the full moon.
By the way, that bright star accompanying the February supermoon is none other than Regulus, the brightest star in the constellation Leo the Lion.
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