The first supermoon since January 30 is scheduled to be seen in the sky on July 12, while two more are forecast later this year.

Supermoons actually denote the moon coming somewhat closer to the earth than its normal orbit. In fact, the consequence of the moon is more obvious on the occasion of a full moon.

Chief scientist at the Goddard Space Flight Center of NASA Dr. James Garvin said, "So, the moon may seem bigger although the difference in its distance from Earth is only a few percent at such times."

Writing on the space agency's website, he added, "It is called a supermoon because this is a very noticeable alignment that at first glance would seem to have an effect. The 'super' in supermoon is really just the appearance of being closer."

NASA further stated, "The scientific term for the phenomenon is 'perigee moon.' Full Moons vary in size because of the oval shape of the Moon's orbit. The Moon follows an elliptical path around Earth with one side ('perigee') about 50,000 km closer than the other ('apogee')."

It added that full moons that occur on the perigee side of the moon's orbit seem extra big and brighter.

According to NASA, depending on the closeness of the supermoon to the earth, it can even appear to the extent of 14 percent bigger in the sky and 30 percent brighter to our eyes compared to the normal moons.

Usually, supermoons are visible after sunset when it becomes dark outside.

Scientists have also forecast that two other supermoons will occur this year on August 10 and September 9. In fact, the August supermoon is expected to be the closest to earth.

EarthSky notes that astrologer Richard Nolle was the first to use the term supermoon over three decades ago, and now it is being used more often to describe the phenomenon. According to Nolle, a supermoon is actually "a new or full moon which occurs with the moon at or close to (within 90 percent of) its nearest approach to earth in a given orbit."

Before the term supermoon came into existence, they were called perigee full moon, or perigee new moon. Perigee denotes "the point in the orbit of the moon or a satellite at which it is nearest to the earth."

The term has been derived from the Greek word "perigeion," which means "close around the earth."