Wanchun Pavilion and Super Moon in Jingshan Park, Beijing. Are you looking forward to the super moon? Our reporter Yao Xueqing Every Mid-Autumn Festival, admiring the moon is an important theme. This year's Mid-Autumn Festival is not only the "fifteenth moon and the sixteent

Wanchun Pavilion and Super Moon in Jingshan Park, Beijing.

Super Moon Are you looking forward to it

Our reporter Yao Xueqing

Every Mid-Autumn Festival, admiring the moon is an important theme. This year's Mid-Autumn Festival is not only the "fifteenth moon and sixteen full moons", but also the second "super moon" of the year.

On the evening of the Mid-Autumn Festival on September 17, after the sun sets, if the weather is good, you can expect to see an almost perfect full moon rising from the horizon in the eastern sky. As the sky gets darker, the full moon becomes brighter and brighter. The bright moonlight will rim the clouds and make the stars "hide"; and at 10:35 a.m. on the 18th, the roundest "full moon" will be ushered in. full moon.

The Mid-Autumn Festival coincides with the "super moon", which is relatively rare. Why do you say this?

"'Super Moon' is not a formal concept in astronomy, but it is worth mentioning from the perspective of viewing. 'Super Moon' means that the moon happens to be at perigee when the moon is full, so it appears big and bright, that is 'The roundest' and the 'nearest' occur at the same time." Zhang Yang, associate researcher at the Purple Mountain Observatory of the Chinese Academy of Sciences, said that we have to start with the orbital movement of the moon around the earth and the changing patterns of the moon's phases. Observing the phases of the moon from the perspective of the earth, the moon waxes and wanes, coming and going again and again. This cycle of changes is called the "synodic moon". Every first day of the lunar calendar, the moon will move between the earth and the sun. The half of the moon illuminated by the sun faces away from the earth, and the moon cannot be seen from the earth. This moment is called "Suo"; and when the moon is illuminated, the moon is not visible from the earth. With that half facing the earth, we can see the full moon. The moon phase at this time is called "looking", which forms the change of "the moon waxes and wanes" seen on the earth. It is worth mentioning that each synodic month does not have exactly 30 days, but an average of 29.53 days. Therefore, the full moon not only appears on the 15th day of the lunar calendar, but also often appears on the 15th day of the lunar calendar, and may even appear on the 14th or 17th day of the lunar calendar.

If we observe the earth and the moon from a distant star, we will see that the moon roughly revolves around the earth along an elliptical orbit, and the earth is at a focus of this ellipse. The moon's revolution period in this elliptical orbit is called a "sidereal month". It is not 30 days, but about 27.32 days. When the moon moves to the position closest to the focus of the earth, it has reached the "perigee", and vice versa, it has reached the "apogee". When the moon is at perigee, it is about 360,000 kilometers away from the earth, and when it is at apogee, it is more than 400,000 kilometers away.

When the moon moves to perigee, various moon phases may occur. If it happens to be a full moon, it will appear larger and brighter than a normal full moon. This moment is called the "perigee full moon" in astronomy, and is called the "super moon" by astronomy enthusiasts. How bright is the "super moon"? Zhang Yang said that compared with the "apogee full moon", which is the smallest full moon, the "super moon" is about 30% larger in apparent area.

How often does a "super moon" occur?

Zhang Yang introduced that by approximate calculation, the answer is the least common multiple of the "synodic moon" and the "sidereal month". It is roughly that a standard "super moon" will appear in the sky every 14 months. However, for the public, there is no significant difference visible to the naked eye when observing the moon with a difference of half a day or one day. Therefore, the full moon within one day near the perigee is counted as a "super moon", which leads to the appearance of the "super moon" we hear about. Somewhat frequently.

For example, this year, there will be four "super moons", namely August 20, September 18, October 17 and November 16. Among them, the one that attracts the most attention is September 18, which is the full moon on the 16th day of the eighth lunar month. "The 'hand-in-hand' between the Mid-Autumn Festival and the super moon will happen once in more than ten years." In Zhang Yang's view, Chinese traditional culture has a special liking for the moon, and the Mid-Autumn Festival pays more attention to "flowers and full moon, reunion of people", so This year's Mid-Autumn Festival is especially worth admiring the moon.

How to appreciate and observe such a "super moon" that holds beautiful expectations?

“It is best to watch it in the evening in a relatively open place.At this time, the moon has just risen and will appear larger. The color of the rising full moon is slightly reddish-yellow. When the moon rises to a certain height, it will gradually turn white. "Zhang Yang suggested that you don't need professional equipment to appreciate the full moon, just the naked eye. If you use a small telescope, you can see the details on the lunar surface clearly, which is very interesting. Photography enthusiasts can also seize the opportunity to "borrow the scenery" of local landmarks Creative photography of architectural or cultural landscapes.

Source: "People's Daily" (Page 05, September 17, 2024)

Source: People's Daily