On this first day of 2018, at 5 p.m. EST (2200 GMT), the full moon will arrive at Perigee, its closest point to Earth in a orbit. Today, our lunar companion reached an extreme perigee distance of 221,559 miles (356,565 kilometers). When these events coincide (a full moon at perigee), some people refer to the event as a "super-moon."
This will be the "biggest full moon of 2018," and the difference in the moon's apparent size, compared with when it's its average distance from Earth, it is 7.3 percent. But that variation is not easily visible to observers
And then there is the other facet: the oft-cited statistic that the perigee full moon is 30 percent bright than a "normal" full moon. But that translates to only a 0.1 or 0.2 magnitude difference in brightness. When the glow of a full moon, the difference is (In fact, most observers can not discern a truly "full" moon from a full moon, and for a day or two before and after peak fullness, many people who see the moon will think it is full.) [Supermoon 2018 Guide: When and How to See January's Two Full Moons
Put another way, if you did not know that the New Year's Day will be the biggest and brightest of the year, would you notice it? Probably not
You can watch webcasts of January's New Year's Day. First, the Virtual Telescope Project by astrophysicist Gianluca Masi will host a free webcast of the full moon rising over Rome, Italy at 11 a.m. EST (1600 GMT) You can watch that webcast live here
At 9 p.m. EST (0100 GMT), the online observatory Slooh.com will offer a live webcast from its remotely operated telescopes around the world. You can see the Slooh super-moon webcast here, though registration for the website - which is free - is required.
Bigger ... brighter ... or just hyperbole?
Most media outlets love to treat a "super-moon" as some sort of special or unusual instance Upon hearing that a particular moon comes with the prefix "super" attached, people rush out to get a look and come away thinking that a rare cosmic alignment. Such feelings put a new spin on the whimsical story in 1837 by Hans Christian Andersen, "The Emperor's New Clothes."
In fact, I got a phone call at New York's Hayden Planetarium from a young woman who was as cheated. "I went out last night to look at that so-called 'super' moon and was very disappointed. It did not look at all brighter than normal." When I queried her on what she expected to see, she replied, "I thought it was going to be something like those three-way light bulbs." When you go from 100 to 150 watts; I thought the moon was going to appear noticeably brighter last night, but it really was not at all! "
Of course, once somebody has said that the moon is closer to normal than Earth and that it will appear slightly larger, so they would like to respond, "Oh yeah! It is normal than the usual!" This is especially true if someone sees the moon near to the horizon, where the enigmatic "moon illusion" always comes into play.
A super-moon every month?
If the criteria for a super-moon is predicted on the moon's arrival at its closest point in its orbit relative to Earth, then the "super" branding is a bit of a misnomer. Indeed, the moon arrives at Perigee every month and sometimes twice in a calendar month. Indeed, now the full moons that instant flank the Jan. 1 perigean full moon is also being branded as super-moons The full moon on Dec. 3 was "super," and the one later this month, on Jan. 31, will be, too And the margin for a super-moon seems to be widening, as full moons that occur within one or two days of perigee are sometimes given the "super" moniker.
Why is not a super-moon at other phases? This year on Halloween, for example, the last-quarter moon will come within 4 hours of perigee. But nobody ever gets excited about a "super" half-moon
The popular astrophysicist Neil degassed Tyson probably said: "In the overall scheme of things, is this relatively small increase in the moon's apparent size really so meaningful? I mean, if you turned a 14-inch pizza in a 15-inch pizza , would you call it a "super-pizza?"
Maybe when it comes to our natural satellite,
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