The “biggest” full moon of the year is to arrive this weekend. The moon will officially become full on Saturday (May 5th) at 11:35 pm EDT and because this month’s full moon coincides with the moon’s perigee – its closest approach to Earth – it will also be the year’s “biggest”. And not only does the moon’s perigee coincide with the full moon this month, but this perigee will be the nearest to the Earth of any this year.
What does all of this mean to sky watchers? This "supermoon" as it is being called should appear about 14% bigger and 30% brighter than lesser full moons in 2012 that occur on the apogee side of the moon’s orbit. The best effect will be to view the moon just after it rises (east) or just before it sets (west) when it is close to the horizon. As far as tides are concerned, the moon will exert about 42% more tidal force than it will during its next apogee two weeks later; however, the slight difference in distance does not lead to any significant impacts on Earth (according to NASA scientists).