No matter how we look at it, the night sky always has something fascinating unfolding. There is one happening tomorrow (June 23). The full moon on Sunday night will be the largest, brightest and the most spectacular moon of the year. Nicknamed ‘supermoon’, the event has already stirred up its fair share of hope, hype and rumours. Here are some facts to understand this celestial phenomenon.
The moon goes through its full cycle of phases in a month, waxing and waning in brightness. This happens from the moon’s changing position relative to the sun and the earth. The orbit of the moon around the earth is oval in shape, which brings the moon to its closest approach to earth once every month. The point of its closest approach is called perigee. This month the moon will go through perigee on the evening of June 23. It will be a full moon phase when it happens. So from our vantage point, we will witness a moon that is bigger than any other. This coincidence is called a supermoon.
So what is in store for those who want to witness this event? The good news is that you don’t need to rush to a planetarium or own a telescope to catch a glimpse of the supermoon. You only have to be at a location from where you can spot the moon sometime during Sunday night.
All that said and done, you may not find the supermoon really that “super”. The moon, by virtue of being closer to earth, will appear only about 15 per cent larger, a difference in size too tiny to take note. To throw in an analogy, the size of a full moon in the sky is roughly the width of your thumb at an arm’s length. A supermoon, though closer, would still be only as big as your thumb making it difficult to tell the difference.
What then about all the rumours of supermoon aftermaths, natural disasters and doomsday scenarios? Before sounding the alarm, it is useful to put these rumours in the right perspective. Though closer, the supermoon would still be at a whopping distance of 3,56,991 kilometres from earth. It’s gravitational tug on earth will only be a tad bit higher than what it is on any typical full moon night. The excess force of the supermoon on you can be easily overpowered if you just walk the opposite way. In short, there will hardly be any dramatic effect on earth, except for the typical high tides in the sea.
Yet, there are some good reasons to catch a glimpse of this phenomenon. Supermoon is a rare occurrence, happening once or twice a year, though full moon and perigee occur once every month. The event also does pose a great opportunity to test your photography skills. Take a zoom-in photograph of the supermoon and juxtapose it with the image of a full moon taken at any other month under identical settings. The difference will be noticeable. And finally, beyond all the fine points, if not anything, it is simply awe-inspiring to stand and stare at a full moon, and with the supermoon it might just get better. So step out this Sunday night and hope the monsoon sky would clear out just in time for the biggest moon of the year.
(The author is an astrophysicist based in the city)
FACT FILE
• On Sunday night the supermoon would rise in our part of the world close to seven in the evening and can be seen throughout the night. Saturday night is also a good time to catch the big moon as it approaches perigee.
• The best time to feel the supermoon effect is when it is closer to the horizon as a backdrop to trees, buildings and other nearby objects. The moon could look unusually big then. But it can happen on any full moon night, and is a standard case of Ebbinghaus illusion, a false visual impression because of the way human brain attributes sizes to objects scattered in the same field.
• The supermoon phenomenon will recur next year on August 10 and again on September 28, 2015 and November 14, 2016
