A supermoon is an astronomical phenomenon where the full moon appears larger and brighter than usual. It happens when a full moon occurs at the same time that its orbit is closest to Earth.
On rare occasions, there will be two supermoons in August – the first of which will occur on August 1st. Supermoons can appear up to eight percent larger than a normal moon.
Understanding the monthly cycle
There are eight phases of the lunar cycle, which repeats every 29.5 days.
The phases are: new moon, waxing crescent, first quarter, waxing gibbous, full moon, waning gibbous, third quarter and waning crescent.
The moon reflects sunlight, and when sunlight reflects off the far side of the moon, it is called a new moon.
When sunlight is reflected from the near side of the moon, it is called a full moon. There are usually three to four supermoons per year.
This year, when the moon is close to Earth, there will be four supermoons in a row, according to science news website EarthSky:
• 2.-3. July: 361,934 km (224,895 mi) away
• August 1: 357,530 km (222,158 miles) away
• 30-31 August: 357,344 km (222,043 mi) away
• 28-29 September: 361,552 km (224,658 mi) away
The supermoon at the end of August will be the closest of the year and is also a blue moon – the second full moon of the calendar month.
What causes a supermoon?
The term “supermoon” was coined in 1979 by astrologer Richard Noll to refer to the point when the full moon is at its closest point in its orbit around Earth.
The Moon’s orbit is elliptical because it follows an oval course around Earth, meaning it is closer and further away from Earth at different times.
The supermoon on August 1 will be about 357,530 km from Earth.
Throughout its orbit, the Moon’s distance from our planet is between 360,000 km and 400,000 km, according to NASA.
Apogee marks the farthest point in the Moon’s orbit around Earth, which is about 405,500 km (252,000 mi) from Earth on average.
Perigee marks the closest point in the Moon’s ellipse, which is about 363,300 km (225,740 mi) from Earth on average.
A supermoon at perigee can appear 14 percent larger and 30 percent brighter than a micromoon that occurs when a full moon coincides with apogee.
A supermoon appears brighter because the closer it is, the more sunlight is reflected off the surface of the moon and reaches Earth. What are the effects of a supermoon?
During new moons and full moons, the Sun, Earth, and Moon align, so the gravitational pull on Earth’s oceans is at its strongest. This phenomenon is referred to as a spring tide.
According to NASA, the tides will be more pronounced with a supermoon, especially if there is an extreme perigee full moon like the one that occurred in November 2016, which was 356,000 km away.
