The Eastern Hemisphere, including New Zealand, will witness the longest lunar eclipse to occur in the 21st century in July.

The eclipse is expected to happen in the early hours of July 28. The spectacle takes place when the Sun, Earth and Moon are directly aligned, and the moon's orbit brings it into Earth's shadow, Business Insider reports.

The Eastern Hemisphere - which will witness the eclipse - generally includes most of Africa, about half of Antarctica, all of Asia, Australia and New Zealand, the Pacific Islands, and most of Europe, according to World Atlas.

It's expected the total eclipse will last for approximately one hour and 43 minutes. Astronomers predict a partial eclipse will then follow, which could last for around three hours and 55 minutes.

The eclipse get its nickname 'blood moon' because the moon will pass directly into the darkest region of the Earth's shadow, called the umbra, which will give the moon a reddish tinge.

The reason the eclipse will last so long is because it will be the smallest and furthest full moon of the year, meaning it will take longer to pass through Earth's dark shadow. It's estimated the longest possible lunar eclipse could last up to one hour and 47 minutes.

This is approximately when Kiwis can watch the eclipse

5:14am: The eclipse begins when the Earth's penumbra begins to touch the moon

7:30am: The total eclipse will make the moon look red

8:21am: You will be able to see a maximum eclipse

9:13am: The total eclipse will end

Newshub.