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Look up: the total eclipse of moon

Fans of the night sky are counting down toward one of nature's most alluring sights: a total eclipse of the moon, which will be visible throughout much of the world Wednesday night.

According to NASA, the total eclipse will be visible in North America, South America, Western Europe and Africa — that is, if clouds don't get in the way.

"Weather permitting, those at Wednesday's World Series game will be able to watch a total eclipse of the moon while watching the game," noted Patrick Wiggins, NASA Solar System Ambassador to Utah.

"Weather permitting" will be the operative phrase here, as well as in St. Louis' open-air stadium.

On Sunday, the National Weather Service forecast for Salt Lake City's weather Wednesday night called for rain, not an encouraging sign. But the forecast could change or the clouds could break for a few hours.

And even if the show is called on account of rain in the Beehive State, residents can still watch it live via the Internet.

Several organizations plan to carry live webcasts of the eclipse. To connect with one of these, point your browser at this NASA site:

"The partial phase of the eclipse will begin at 7:14 p.m. MDT when the moon is still very low in the Eastern sky for observers here in Utah," Wiggins said. "But by 8:23 when totality begins it will be about a quarter of the way up the sky and well placed for viewing."

If storm clouds don't get in the way, the Salt Lake Astronomical Society will open its Harmons Observatory at Stansbury Park to the public. They may be especially eager to see Earth's shadow creep across the moon through telescopes since, according to Wiggins, this will be the last total eclipse to be visible from Utah for nearly three years.

For an hour and 22 minutes, he added, the moon will be fully immersed in the shadow of our planet. During this time it may assume a coppery or blood-red coloration. Other possibilities, according to NASA, include bright orange, dark brown or the much rarer dark gray.

That the moon can be seen at all during the total phase of an eclipse is due to sunlight reflecting from Earth and hitting the orb while it is overshadowed by Earth. Dust and smoke in our atmosphere absorbs much of the bluer parts of the sun's spectrum, making the resulting reflected light look reddish.

The state of the atmosphere and the amount of light reflected into space determines how the moon will look. In the past, those who tried to predict the brightness or tint of the moon during an eclipse sometimes were far off the mark.

Wiggins said Luna will begin to emerge from the eclipse at 9:45 p.m. By 10:54 p.m., it will be out of the dark part of Earth's shadow, the umbra. It will leave the penumbra, a fainter part of the planet's shadow, later. But NASA says the penumbral phase may be too subtle to detect by eye.

Mark Bloomenthal, vice president of the society, points out that lunar eclipses occur when the moon passes into Earth's shadow. On the other hand, solar eclipses happen when the moon goes across the face of the sun as seen from particular paths on Earth.

Unlike eclipses of the sun, which require special observing equipment to prevent damage to the eyes, moon eclipses can be viewed safely without special gear, he added in a press release from the society.

The Harmons Observatory is part of the society's Stansbury Park Observatory Complex. To reach SPOC from Salt Lake City, drive west on I-80, take Exit 99 (the Stansbury and Tooele exit) and follow the signs south. Signs will indicate Stansbury Park and the observatory.

Those in wheelchairs may use a telescope especially designed for them.

"Drive time from downtown Salt Lake City is about 35 minutes," Bloomenthal wrote. Of course, the eclipse viewing will be held only if the weather allows. He added, "No reservations are required and there is no charge for admission."