JAKARTA, NNC – January 2018 is a good month for the stargazers to be treated to. The new year was brought in with a stunning supermoon on the night of Jan. 1. And luckily, we don't have long to wait until the next one.
According to NASA – the next supermoon in 2018 will be on the night of Jan. 31. Moreover, since it's the second full moon in the same calender month, it technically becomes a "blue moon" - an event that only happens every couple of years.
Supermoons are so-called because they appear larger and brighter in the sky than a regular full moon.
“The supermoons are a great opportunity for people to start looking at the moon, not just that once but every chance they have!” said Noah Petro, a research scientist from NASA’s Goddard Space Flight Center, as quoted by the BBC on Friday (1/12/2018) ).
According to him, the best time to look up is on the nights of Jan. 31 and Feb. 1 at about 2 AM (GMT). There's a window of opportunity if there are clear skies.
A supermoon usually takes place every one to two years, when the full moon coincides with its closest point to Earth during its monthly orbit. Because the moon has an elliptical orbit, one side - called the perigee - is about 48,280 km (30,000 miles) closer to Earth than the other side (the apogee). When the sun, the moon, and Earth line up as the moon orbits Earth, that's known as syzygy.
When this Earth-Moon-Sun system occurs with the perigee side of the moon facing us, and the moon happens to be on the opposite side of Earth from the sun, we get what’s called a perigee-syzygy.
That causes the moon to appear much bigger and brighter in our sky than usual, and it's referred to as a supermoon - or more technically, a perigee moon.
It's the rare moment when a second full moon appears during one calendar month, although its traditional meaning is slightly different. A lunar month lasts about 29.5 days, whilst human months last anything between 28 and 31 days.
Sometimes, this this means that a full moon can be seen twice in a month - which is referred to as a blue moon. Moreover, the supermoon on Jan. 31 will also enjoy a lunar eclipse.
"The moon’s orbit around our planet is tilted so it usually falls above or below the shadow of the Earth. About twice each year, a full moon lines up perfectly with the Earth and sun such that Earth’s shadow totally blocks the sun’s light, which would normally reflect off the moon." explained NASA.