Northland skywatchers will get to see the spectacle in the early hours of tomorrow, if the clouds stay away for it to be observed.

It will mean getting out of bed very early - or staying up very late - with a very rare "super blue blood moon eclipse" visible above New Zealand on February 1 at 2.30am.

Unfortunately, the forecast is for rain tonight/tomorrow.

A blue moon is the second full moon in a month. A supermoon is a particularly close full or new moon, appearing somewhat brighter and bigger. A total lunar eclipse — or blood moon for its reddish tinge — has the moon completely bathed in Earth's shadow.

Peter Felhofer, president of the Northland Astronomical Society, said the moon would be a spectacular sight for those who did see it.

He said in New Zealand the moon was technically not a blue moon because it occurs about 2.30am on February 1, but for the rest of the world it is. He said this might be splitting hairs, but there was still plenty to get excited about.

''It's particularly exciting that the lunar eclipse is happening on a super moon and the moon is expected to be anything from a deep red to purple, so it should be quite a sight for those who do see it."

But compounding the situation further than the possible cloud dolour is that it can be hard to spot the moon when there is a lunar eclipse," Mr Felhofer said.

''Normally you'd look for the biggest bright thing in the sky, but it's going to be dark and if the moon is purple it will be very hard to spot in the night sky

''But it will be going for a long time, with the first sighting just before midnight then it is entering the umbra [shadow of the Earth] about 1.30am. Then after 1.30am it goes into the full umbra and at 2.30am it will be right in the middle of the eclipse.''

He said if a person stood facing north they should look straight up in the early hours of tomorrow morning for the best chance of seeing the rare event.

The moon will actually be closest to Earth on Tuesday — just over 223,000 miles (359,000 kilometers). That's about 1,500 miles (2,400 kilometers) farther than the supermoon on Jan. 1. Midway through Wednesday's eclipse, the moon will be even farther away — 223,820 miles (360,200 kilometers) — but still within unofficial supermoon guidelines.

As the sun lines up perfectly with the Earth and then moon for the eclipse, scientists will make observations from a telescope in Hawaii, while also collecting data from NASA's moon-circling Lunar Reconnaissance Orbiter, launched in 2009.

Just like the total solar eclipse in the U.S. last August cooled the Earth's surface, a lunar eclipse cools the moon's surface. It's this abrupt cooling — from the heat of direct sunlight to essentially a deep freeze — that researchers will be studying.

Totality will last more than an hour.

- additional reporting at the Northern Advocate