Anchorage Daily News

FAIRBANKS -- Alaskans can witness an astronomical phenomenon today even without a telescope.

If skies are clear, they can see Mars slip behind the moon for nearly an hour before popping out again, an astronomical peek-a-boo called an occultation.

The lunar occultation of Mars will take place from 4:52 p.m. to 5:43 p.m., according to local astronomer Martin Gutoski, president of the Fairbanks Astronomical Unit. The club will have telescopes set up at Creamer's Field, Gutoski said.

But no telescope is needed.

"It's pretty much a naked-eye thing," Gutoski said. "You can see the moon heading right toward it.

"You'll see it come and go," he said. "It'll be cool."

An occultation is a fancy name for an eclipse, where one object bigger than another blocks out the smaller object, Gutoski said. A lunar occultation occurs when the moon, which moves across the sky at a rate of roughly 13.5 degrees a day, passes in front of a star or planet.

The occultation will take place 16 degrees above the horizon, he said. That should be high enough to be over mountains for viewers looking northeast in Anchorage, he said. If skies are clear and no mountains are in the way, all Alaskans should be able to see it, he said.

The moon is the most occulting body in the solar system because it's so big in the sky compared to stars and planets. There are also lunar occultations of Jupiter and Saturn.

Mars is now in opposition, meaning it is the closest to Earth it will be during its 26-month orbit. It won't be this close to Earth again until 2016, Gutoski said.

It will be obvious when Mars disappears, but it will be harder to see Mars when it appears from behind the moon because the moon's glare is so bright, he said.

Lunar occultations look different from various points on Earth. In this case, the farther north you go, Mars will hide behind a bigger portion of the moon. People in central Washington and Calgary, Alberta, will get a chance to view a "grazing occultation" where Mars just skids along the bottom edge of the moon.

"Grazings are the niftiest ones because the craters and mountains of the moon make the occulted object wink and blink as they are briefly shaded as they skid by the wrinkly profile of that limb," Gutoski said.

Before lunar orbiters and landers returned information about the geography of the moon's surface, astronomers relied heavily on occultations to visually telegraph a particular outline as seen from different locations simultaneously on the Earth, said Gutoski.

"Even though this one will be a full moon event and not be a grazer for Fairbanks, just seeing a planet slip behind the moon is somewhat rare," he said.

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