The longest partial lunar eclipse in the last 580 years will occur late Thursday night and early Friday morning, and this phenomenon, weather permitting, will be visible in all 50 U.S. states, but also in most of the world. Unfortunately, the eclipse will not be seen in Croatia.

Lunar eclipses occur when the Sun, Earth and full Moon form an almost perfect line in space and when the Earth passes between the Moon and the Sun, so that the shadow of our planet ‘covers’ the Moon.

The moon is at its furthest point from Earth during an eclipse and gradually slides into the Earth's shadow until most of its disk changes from a silver-grey to a dark orange or red colour of mahogany, the American Astronomers Association said.

The peak of the partial eclipse will occur early on Friday when 97 percent of the Moon will be covered by the Earth's shadow, writes USA Today.

According to NASA, the eclipse will last three hours and 28 minutes, which is the longest partial lunar eclipse in this century and the longest in the last 580 years.

The last partial lunar eclipse that lasted longer occurred on February 18, 1440, and the next time such a long partial lunar eclipse from Earth will be visible on February 8, 2669.

For observers on the east coast of America, the eclipse begins just after 2 a.m. on Friday, and will reach its maximum at 4 p.m. For West Coast observers, it starts just after 11pm on Thursday and reaches a maximum on Friday around 1am after midnight.

Unlike a solar eclipse, you do not need special glasses to observe this phenomenon.

"Partial lunar eclipses may not be as spectacular as its total eclipses - when the Moon is completely covered by the Earth's shadow, but they are more common," NASA said.

Except in North America and Hawaii, the eclipse will be seen in parts of Russia, and observers in South America and Western Europe will see the moon set before the eclipse peaks.

It will be well seen in Australia, New Zealand, Japan, China and Southeast Asia, but no phase of the eclipse will be visible from Africa, the Middle East and West Asia.