The Moon and Mars will be putting on a show this July, even if New Zealand doesn't get to see all of the event being dubbed the longest lunar eclipse of the century.

"It will be something worth getting up early to go and see," says Otago Museum director and astronomer Dr Ian Griffin.

According to Nasa, the Moon will be in full eclipse - or totality - for 103 minutes. But the Moon will enter totality not long before setting in this country, on the morning of July 28.

The Royal Astronomical Society of New Zealand website shows the total eclipse - or blood moon - starting in New Zealand at a few seconds before 7.30am. The Sun then rises in Wellington just a minute later at 7.31am, while the Moon sets a few more minutes after that at 7.38am.

New Zealand does see the earlier stages of the eclipse, with the Moon entering the penumbra - or light shadow - at 5.14am and the umbra - dark shadow - at 6.24am.

Within days of the eclipse Mars will also be making its closest approach to the Earth in 15 years, getting to just 57.6 million kilometres away.

By comparison, the average distance between Earth and Mars is 225 million kilometres. At their furthest from each other, the two planets can be around 400m km apart.

Otago Museum's Griffin will be part of joint project between the museum and Canterbury University at Mt John Observatory, Lake Tekapo to take photographs of Mars in the last week of July and post them on the internet. He is hoping to see the lunar eclipse from the observatory, depending on the weather.

"Because it's the full moon, the Moon sets when the Sun rises. We will actually be able to see the total eclipse as the Moon is setting, and the Moon will set in total eclipse, which will be a real cool view," says Ian.

"Also that week, Mars is at the closest it's been since 2003, so Mars will be really bright in the sky."

Already Mars is unusually bright. "If you go out after sunset, about 8pm, it's rising in the eastern sky. It's incredibly bright and incredibly red," says Ian.

"On the night of the lunar eclipse, Mars is quite close to the Moon (in the sky). At the end of the night you have a bright red-coloured Mars close to a red-coloured Moon in the sky," he says.

Mars is red because it is covered in a layer of dust mainly made up of iron, which has rusted.

The Moon can appear red during an eclipse - and is sometimes referred to as a blood moon - because during an eclipse sunlight passes through Earth's atmosphere and is refracted onto the Moon, creating the blood-red colour.

"Basically when Mars is opposite the Sun in the sky, which it will be in late July, it rises at sunset and sets at sunrise." It would be "very very bright" during the last week of July.

It would be possible to see the eclipse throughout New Zealand, provided the sky was clear, Griffin said.

"All you need on that morning, because the Moon's quite low in the sky, you will need an unobstructed view to the horizon, and you well also need good weather."

Mars close approaches happen about every 26 months, and is the point where Mars and Earth are closest to each other in their orbits around the Sun.

The 2003 close approach was the closest in nearly 60,000 years, with the two planets within 55.8m km of each other.

-Additional reporting Stuff