Stargazers, here's what to expect as a rare blood supermoon gets set to light up NZ's sky

Tuesday, 25 May 2021

A rare blood supermoon is set to light up New Zealand's sky on Wednesday night. Photo: File photo from the Stardome Observatory.

Click here to follow Stuff’s live coverage of Wednesday night’s supermoon.

People are in for a spectacular sight, with a blood supermoon set to light up the night sky.

It's thought Wednesday night’s appearance will be the first time in nearly 40 years since New Zealanders saw the astronomical phenomenon of a blood supermoon – where a total lunar eclipse happens at the same time as a supermoon.

Stargazers won’t need to rush out and buy a telescope. Experts say the blood supermoon will be visible to the naked eye, and is expected to be spotted from most parts of the country as long as it’s not too cloudy. According to Nasa, this is the year’s “most super” moon.

Send your photos and videos of Wednesday night’s blood supermoon to newstips@stuff.co.nz.

A “pink” supermoon seen in New Brighton, Christcurch in April this year.

* 'Pink' supermoon lights up New Zealand's sky

* Dramatic 'half-blood' moon as New Zealand sees start of partial lunar eclipse

* Lunar showstopper: First super blue blood moon delights around the world

Stargazers went outdoors to watch a “pink” supermoon rise in New Brighton, Christchurch, in April.

A blood supermoon is a combination of three factors: a full moon, the Moon being at its closest point to Earth in its orbit, and a total lunar eclipse.

The last time one was visible from Aotearoa was in 1982.

A lot of eyes will be on the skies around the globe, however, Nelson-based space scientist Dr Duncan Steel said New Zealand would likely be the best location for watching this eclipse.

Stardome Observatory and Planetarium astronomy educator John Rowe said the phenomenon was eagerly anticipated by Kiwi space enthusiasts.

Although blood supermoons occur every few years, they aren’t always visible in Aotearoa. “We’ve waited almost 40 years for this, so it’s exciting, Rowe said.

A super blue blood moon seen in February, 2018 in Somerset, England.

“All Kiwis need to do is look high into the night sky on Wednesday evening and they’ll be treated to a stunning sight.”

When and where to watch it

The lunar eclipse will last for about five hours in total, beginning shortly before 9pm on Wednesday May 26 and finishing in the early hours of the morning.

But the key period of “totality” – when the Moon is entirely hidden by Earth's shadow – will take place between about 11.11pm and 11.25pm. The Moon will also appear rusty red in colour and slight larger than usual.

University of Auckland senior lecturer of physics Dr Nicholas Rattenbury said the Moon will appear to have a slightly dullish red, or possibly salmon-coloured look to it during its period of totality.

This “fun effect” is related to how sunlight bends and scatters as it passes through Earth’s atmosphere. In the air, blue and violet colours scatter more widely which is why the sky appears blue, Rattenbury said. Meanwhile, red light travels a straighter path through the air.

During a total lunar eclipse, the Earth blocks the Sun’s direct light so only heavily filtered reddish light bends through the atmosphere and reaches the Moon.

According to Nasa, the more dust or clouds in Earth’s atmosphere during the eclipse, the redder the Moon will appear.

According to Niwa, the best places to view the blood supermoon will likely be: Southland, Otago, the West Coast, Canterbury, Tasman, Nelson, Marlborough, Wellington, Manawatū-Whanganui, Taranaki, Waikato and Auckland.

On Wednesday afternoon, Niwa meteorologist Ben Noll said the thickest cloud cover is forecast in the eastern areas of the North Island, from Gisborne down to parts of Hawke's Bay, and possibly extending into the Wairarapa.

Some scattered cloud may also appear in eastern Hawke’s Bay, stretching into the Central Plateau. Some scattered cloud could also appear in Northland, Coromandel, and about Great Barrier Island.

Noll said stargazers shouldn’t be discouraged however, because there may be enough breaks in the cloud to spot the moon.

Much of the South Island is expecting relatively clear skies, with just some scattered cloud for Stewart Island and possibly southern Fiordland.

Noll said on the whole, “the odds are in our favour”, with roughly 80-90 per cent of the country expected to be able to see some of the show.

Rattenbury said he thought it was cool that people were interested in the Moon, and other space events.

“I think it’s just really neat that when these events occur that people get excited, and they want to go and take a look.”