On the evening of August 8, the night sky will appear the second "supermoon" in 30. "Supermoon" refers to the full moon when the moon is located near perigee, because this is the second full moon in a month, so it is also called "blue moon".
【During the same period】Xiu Lipeng, member of the Chinese Astronomical Society and expert in astronomy science
We all know that when the Moon and the Sun are on opposite sides of the Earth, and the ecliptic longitude of the Moon and the Sun are 180 degrees apart, the Moon we see on Earth is the most round, and we call it the "Full Moon" or "Look". At the same time, the orbit of the moon is an ellipse, which means that its distance from the earth is close and far, so the difference between the apparent diameter of the largest moon and the smallest moon is about 14%. There are about 12 to 13 full moons every year, and if the full moon occurs when the moon is near perigee, it is what we commonly call a "supermoon". In the West, it calls the second Full Moon in a Gregorian month the "Blue Moon", but in fact when the "Blue Moon" occurs, the Moon does not turn blue. Because "blue moon" means "rare thing" in English, it is possible that two consecutive full moons in a Gregorian calendar month are rare, so they call this "blue moon".
According to experts, compared with the beginning of the month, the "supermoon" on the 30th is the first to reach the perigee, and then the roundest. Visually, it will be slightly larger than the "supermoon" at the beginning of the month.
【During the same period】Xiu Lipeng, member of the Chinese Astronomical Society and expert in astronomy science
Our Gregorian calendar is (usually) 30 or 31 days a month, and then in the lunar calendar guided by the phase of the moon, the synodic period of the moon is about 29.5 days, so there are two full moons in a Gregorian month like this, basically once in 2 to 3 years. At the beginning of this month, on August 8, this full moon is also a "supermoon", and its apparent diameter is about 2 hours away from perigee, and its apparent diameter is 11 arcminutes and 33 arcseconds. Although the "supermoon" on the 39th was the next day, that is, around 30:31 am on the 09st, when we observed it the night before, that is, on the night of the 35th, the moon was just past perigee. So it is closer than the 30 hours on the 2nd, and its apparent diameter can reach 11 arc minutes and 33 arcseconds, so this full moon is the largest full moon of this year (47).
In addition, on the night of the "supermoon", Saturn will also accompany the moon. When the Moon rises above the eastern horizon, Saturn will gradually appear to the left of the Moon, about 5 or 6 degrees away from the Moon.
【During the same period】Xiu Lipeng, member of the Chinese Astronomical Society and expert in astronomy science
The sun sets and the moon rises, then you can look to the southeast, a large full moon will be slightly red at the beginning of the rise, and then when its height is getting higher and higher, it will appear a bright white that can be observed all night. On the night of the 30th, we can see not only the "supermoon", but also Saturn around it. At the same time, we may wait until a little later, such as around the wee hours of the morning, to see Jupiter rising from the eastern horizon, both of which are brighter and more recognizable, and can be seen in cities.
Reporter Cheng Yu reported from Beijing
Responsible Editor: [Li Ji]