12年最大的月亮

新华网南京1月10日电 天公作美，10日晚比平时“大”了约1／6的圆月如约现身苍穹，中国绝大部分地区的公众都欣赏到了这一精彩天象。

中科院紫金山天文台研究员王思潮介绍，10日晚19时月球将运行到离地球最近的地方，距离仅 为35．75万千米，比月球离地球的平均距离38．44万千米要近2．69万千米。此时，与1月11日上午11时27分月亮望（满月）的时间很接近。正因 如此，当晚，月亮看上去将比平时“大”上16％左右，分外生辉。

“三九”严寒阻挡不了人们赏月的脚步。10日晚，在南京、天津、北京等城市，不少公众走出户 外观赏明月。“9日晚我就觉得月亮看上去比平时‘大’，只不过还不够圆。”带着家人特地赶到秦淮河边赏月的南京市民陈华告诉记者，经过了整整一天后，10 日晚的月亮又大又圆，格外好看。

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Saturday night special: Biggest full moon of '09

If skies are clear Saturday, go out at sunset and look for the giant moon rising in the east. It will be the biggest and brightest one of 2009, sure to wow even seasoned observers.

Earth, the moon and the sun are all bound together by gravity, which keeps us going around the sun and keeps the moon going around us as it goes through phases. The moon makes a trip around Earth every 29.5 days.

But the orbit is not a perfect circle. One portion is about 31,000 miles (50,000 km) closer to our planet than the farthest part, so the moon's apparent size in the sky changes. Saturday night (Jan. 10) the moon will be at perigee, the closest point to us on this orbit.

It will appear about 14 percent bigger in our sky and 30 percent brighter than some other full moons during 2009, according to NASA. (A similar setup occurred in December, making that month's full moon the largest of 2008.)

High tides
Tides will be higher, too. Earth's oceans are pulled by the gravity of the moon and the sun. So when the moon is closer, tides are pulled higher. Scientists call these perigean tides, because they occur when the moon is at or near perigee. (The farthest point on the lunar orbit is called apogee.)

This month's full moon is known as the Wolf Moon from Native American folklore. The full moon's of each month are named. January's is also known as the Old Moon and the Snow Moon.A full moon rises right around sunset, no matter where you are.

That's because of the celestial mechanics that produce a full moon: The moon and the sun are on opposite sides of the Earth, so that sunlight hits the full face of the moon and bounces back to our eyes.

At moonrise, the moon will appear even larger than it will later in the night when it's higher in the sky. This is an illusion that scientists can't fully explain. Some think it has to do with our perception of things on the horizon vs. stuff overhead.

Try this trick, though: Using a pencil eraser or similar object held at arm's length, gauge the size of the moon when it's near the horizon and again later when it's higher up and seems smaller. You'll see that when compared to a fixed object, the moon will be the same size in both cases.

More lunacy
If you have other plans for Saturday night, take heart: You can see all this on each night surrounding the full moon, too, because the moon will be nearly full, rising earlier Friday night and later Sunday night.

Interestingly, because of the mechanics of all this, the moon is never truly 100 percent full. For that to happen, all three objects have to be in a perfect line, and when that rare circumstance occurs, there is a total eclipse of the moon.

A departing fact: The moon is moving away as you read this, by about 1.6 inches (4 centimeters) a year. Eventually this drift will force the moon to take 47 days to circle our world.

This view of a full moon was photographed by an Expedition 14 crewmember onboard the International Space Station. Earth's horizon and airglow is visible at left.