As if you needed an excuse to look up at the night sky, this Sunday (June 23) the full moon will seem especially big and bright. It will be most striking when it’s near the horizon.
What causes a Supermoon?
The Moon is an elliptical orbit around the Earth, meaning that its distance from the Earth can vary from a minimum of 357,000 km to a maximum of 407,000 km. The average perigee and apogee are 363,300 km and 405,500 km, respectively, and the variation over the course of the year is due to the Sun's gravitational influence as the Earth and Moon move along their orbit throughout the year. The coincidence of a full moon and the perigee (closest distance) is what dictates a Supermoon, which is what will occur on Sunday.
What to expect: