July Full Moon: An optical illusion will make the moon appear abnormally large. Here's why

The full moon of July will rise on 10 July and will be an opportunity to witness an optical effect known as the Moon illusion. The moon will appear extremely huge because of this illusion when it is close to the horizon. July's full moon is also known as the Buck Moon which will appear especially low in the sky after sunset. The moon will move slowly across the sky at a very shallow inclination. This is because of its proximity to the summer solstice. At this time, the sun is at its highest in the daytime sky, resulting in the moon tracking a lower path through the night, Space.com reported. This year, this view will appear even more stark because of a phenomenon known as a 'Major Lunar Standstill'. It occurs every 18.6 years. At this time, "the sun's gravity drags the moon's tilted orbit into its most extreme inclination relative to Earth's celestial equator." Also Read: GREAT WALL of universe: 10 billion light-years cosmic monster detected in space should not exist

Why is the moon low or high?

A full moon occurs when the moon is directly opposite the sun in the sky. At this point, it appears fully lit from Earth. Here, its ecliptic longitude is 180 degrees from the Sun. The ecliptic is an imaginary plane which marks the Earth's orbit around the Sun and also marks the path the Sun takes across the sky throughout the year. Meanwhile, the Moon’s orbit is inclined to the ecliptic by around 5 degrees. If looked at as two hoops, one on top of the other, the moon will at times be above Earth's hoop, and at others below, BBC explains. It is joined at two points known as nodes. One of them takes the Moon higher, and on the other one, it descends. Also Read: Scientists use NASA's TESS to discover ‘super-earth’ that could host billions—Is TOI-1846 b humanity's next home?

Every 18.6 years, the nodes precess around the ecliptic once. During this period, the moonrise and moonset points on the horizon are at the farthest point during the 18.6-year cycle. This happens because the Moon's orbit tilts and wobbles. Right now, there is a major lunar standstill. So the moon will appear enormous very close to the horizon.

When to watch July's full moon and illusion?

The best time to watch the abnormally large moon is just after sunrise, whose timing will depend on the region you are in. July's full moon is also known as The Buck Moon because at this time of year in North America, the male deer, known as bucks, begin to grow out their antlers. It is also called the Thunder Moon because of the summer storms in some parts of the US in July.