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June 26 lunar eclipse heightens the ‘moon illusion’ effect
by Sophie Anderson - June 27, 2010 - comments
The moon illusion is an optical illusion in which the moon appears larger near the horizon than it does while higher up in the sky. The June 26 partial lunar eclipse made the moon look unusually large in most parts of the U.S. and Canada.
It was a feast for the eyes as more than half of the moon's surface was shaded during the partial lunar eclipse early Saturday morning.
The eclipse which began at 1017 GMT lasted close to three hours.
Moon illusion effect
Viewers in North America witnessed an “unusually magnified” eclipse as the moon entered the shadow of Earth.
People in most parts of the U.S. and Canada witnessed a moon that appeared larger than usual, a phenomenon known as the "moon illusion."
Moon illusion occurs when the moon is close to the horizon at the time of the eclipse. NASA explained that low-hanging moons look "unnaturally large when they beam through trees, buildings and other foreground objects."
As much as 54 percent of the moon's diameter was covered when the eclipse was at its peak. The peak phenomenon occurred at 1138 GMT.
The Saturday’s eclipse is stated to be the preview to the total lunar eclipse due in December when the Earth’s shadow will completely engulf the Moon. That site would be visible all over North America.
"The moon will look as though a big bite has been taken out of it," Sydney Observatory acting manager Geoff Wyatt said before the eclipse began.
"Once it goes over 50 per cent it then starts to look like a crescent you get every month, but up until then it is really quite intriguing," he added.
Viewers in UK and Europe were devoid of the spectacular site due to the timing of the partial lunar eclipse.
"Observers in India, Japan, and parts of East Asia will experience the same phenomenon. They'll see the eclipse on Saturday evening as the Moon is rising," NASA wrote on its website.
Total eclipse in December
Saturday's partial eclipse did not reach "totality" as the Moon, Sun, and Earth were not aligned.
NASA states that the June 26 partial lunar eclipse belonged to Saros 120, a series of 83 eclipses. Lunar eclipses of Saros 120 occur at the moon’s ascending node and the moon moves southward with each eclipse.
The Saturday’s eclipse is stated to be the preview to the total lunar eclipse due in December when the Earth’s shadow will completely engulf the Moon. That site would be observable all over North America.
"So we don't get to see that washed out red colour of light bending through the earth's atmosphere that you get during totality, which is really cool," Wyatt said of what the total eclipse will have to offer.
The lunar eclipse occurs about four times every two years, when the earth travels between the sun and the moon.