Bengaluru, Jan 31 (IANS): Thousands of skywatchers across this tech hub are waiting for a rare celestial spectacle when the Moon will appear brighter and turn red during an eclipse later on Wednesday.

"This lunar eclipse is special because a supermoon (appears larger than usual in its perigee), blue Moon (second full Moon of the month) and blood Moon (appears red during eclipse) will all coincide at once," the Director of Nehru Planetarium Pramod G. Galgali told IANS here.

A few thousand people are expected to visit the Nehru Planetarium in the city centre on Wednesday evening to witness the celestial treat, which begins at about 6.21 p.m. and will last till 7.37 p.m.

The planetarium will be arranging telescopes and binoculars for people to enjoy the lunar spectacle clearly.

"The spectacle is completely safe to watch with naked eyes," the planetarium director said.

The rare spectacle is said to be occurring for the first time since 1982, when a blue Moon and total lunar eclipse together was last visible in India.

The moon has an elliptical orbit, and during its revolution around the earth, it gets closest to us at one point -- known as perigee.

"When Moon is in perigee, it appears nearly 10 per cent or more bigger than usual. This is known as a supermoon," Galgali explained.

It is also the second full moon of the month, commonly known as a "blue moon". The last full moon of the month was on January 2.

"It is a normal full moon, blue moon is just a name given to the second full moon of the month," he said.

Due to the total lunar eclipse, the Moon will appear reddish, due to which it is known as a "blood Moon".

The lunar eclipse will begin at 4.21 p.m., which is when the Moon enters the Earth's lighter shadow -- known as penumbra.

"The Moon will then enter the darker shadow of Earth, umbra, by about 6.21 p.m., that is when it is visible with a red tint till nearly 7.37 p.m.," Galgali added.

The eclipse will be completely over by 9.38 p.m., when the Moon will exit the Earth's shadow entirely.