The National Astronomical Research Institute of Thailand says that the April astronomical phenomenon coincides with the perigee – the point in the orbit of the Moon which is nearest to the earth – so that the full moon will appear larger-than-usual.
This fluctuation in the full moon’s distance from Earth is caused by the fact that the moon’s orbit around the Earth isn’t perfectly circular but very slightly elliptical. If the full moon occurs closer to the perigee (the closest point to Earth on this slightly elliptical orbit), it can appear bigger than if it occurs closer to the apogee (the farthest point).
NARIT has a few tips to get a great photo of tonight’s phenomenon. Use telephoto lens with focal length over 300mm and set your camera’s ISO at 400 or over. (NNT)