WASHINGTON, Feb. 19 (Xinhua) -- Residents of the Americas, Europe and Africa will have the best view of a total lunar eclipse in the late night hours of Feb. 20, U.S. space agency NASA forecast Tuesday.

    In the United States, the entire eclipse will be visible for the majority of the country. However, residents on the West Coast will miss out on watching the early stages of the eclipse, as it begins before moonrise.

    This lunar eclipse may be worth staying up for, because it will be the last one until December 2010, said NASA.

    A lunar eclipse occurs when the Earth lines up directly between the sun and the moon, casting a shadow over the moon's surface.

    The Feb. 20 eclipse will last for nearly three and a half hours. For a full 50 minutes of that time, the moon will be in totality -- the period when the lunar surface is completely covered by the Earth's shadow.

    During an eclipse the moon changes color, going from a light gray color to an orange or deep red shade. This is totality.

    The moon takes on this new color because indirect sunlight is still able to pass through the Earth's atmosphere and cast a glow on the moon.

    The exact color of the moon depends on the amount of dust and clouds in the atmosphere. If there are extra particles in the atmosphere, stemming from a recent volcanic eruption, the moon will appear a darker shade of red.