Blue Moon & Supermoon: Rare August Celestial Events

 The phrase "Once in a Blue Moon" is often used to depict occurrences that are infrequent, perhaps even preposterous. After all, it's not every day that you witness a blue moon, is it? Mark your calendars for August 31st because a "Blue Moon" is anticipated. As per contemporary lore, a Blue Moon signifies the second full moon in a given calendar month. Typically, a month has a single full moon, but occasionally, a second one sneaks in. Since full moons are separated by 29 days and most months have 30 or 31 days, it's feasible to have two full moons within the same month. 

This rare event takes place approximately every two and a half years. August 2023 is one such month with two full moons; the first one today, August 1st, and the second one, August 31st, is technically a Blue Moon. But will it truly be blue? Not really. The moon's color doesn't change based on the date of a full moon, so on August 31st, expect to see the usual pearly grey moon. Here, 'blue' is a metaphor for rarity.

Intriguingly, both full moons in August will be supermoons! A Supermoon is when the moon, in its full phase, is at its closest point (perigee) to the Earth. So what's so exceptional about a Supermoon? It presents a learning opportunity for observers. For instance, the Moon orbits the Earth in an elliptical path, drawing it closer and farther to our planet. The farthest point in this path, apogee, is approximately 405,000 kilometers from Earth. However, when it's at perigee, the closest point, it averages a distance of about 363,000 kilometers from Earth. A full moon at perigee appears slightly larger and brighter than the average full moon, hence the term Supermoon.