North and South America will see a red moon, or Blood Moon, in a full lunar eclipse early Friday -- but it may be difficult to see on Long Island.
The National Weather Service forecasts partly cloudy skies Thursday night into Friday, due to high-pressure systems in the Northeast and low pressure in the Southwest.
"I would say it's not looking good for viewing," Bryan Ramsey, a service meteorologist said. "Pretty much all of New England is going to be cloudy at that time."
Frederick Walter, professor of astronomy at Stony Brook University, said the eclipse will begin around 11:57 p.m. Thursday, as the moon goes through the center of the Earth's outer shadow, or penumbra.
By 1 p.m., Friday, the moon enters the umbra, or the planet's innermost shadow.
Around this time viewers can see a "crescent eating into the moon," Walter said.
The eclipse has full totality around 2:30 a.m., when the moon is directly in line with the Earth. Totality will last until around 3:30 a.m., the moon becoming more red over time.
With the right conditions, the eclipse will be visible to viewers on the Western Hemisphere in the Pacific, the Americas, Western Europe and Western Africa, according to NASA's website.
No special glasses or equipment are needed.
Walter said that when an eclipse occurs, we do not see complete darkness because some of the Sun's rays shine past the Earth.
"The reason it looks red is that it's being illuminated by light refracted to the Earth's atmosphere," he said.
Colors like reds and oranges have longer wavelengths and can travel past the Earth's atmosphere, Walter said.
But colors like blues and violets scatter more easily and are omitted once they hit the Earth's atmosphere, the reason our sky is blue, Walter said.
Lunar eclipses are quite frequent, as the moon orbits through the Earth's shadow at least once a month.
The next lunar eclipse, also a total, will occur on Sept. 7, but it will be visible to viewers on the Eastern Hemisphere.