In the early morning of July 25, a spectacular celestial phenomenon that is very suitable for the public to observe on the mainland, the lunar occultation of Saturn, will be staged, and interested astronomy enthusiasts must not miss it.
This is Saturn and the Moon photographed on the evening of September 8, 2019 in Huangcaowan Country Park, Chaoyang District, Beijing. (Photo by starry sky photographer Huang Huang)
During the Moon's survey, the background planets (or stars) are obscured by it, a phenomenon called an occultation. Lunar occultation is a very popular type of celestial phenomenon for astronomy enthusiasts, especially the lunar occultation of Venus, Mars, Jupiter and Saturn, these planets are very bright and have a large apparent diameter, and you can see the edge of the moon in the telescope "cannibalizing" the planets little by little, which is very interesting.
Saturn is the second largest planet in the solar system, after Jupiter, and is surrounded by a beautiful ring on its equatorial plane. Viewed from the astronomical telescope, Saturn resembles a "straw hat" and is known as the "straw hat star". Due to Saturn's beautiful form, the lunar occultation of Saturn is also one of the many lunar occultations that are very ornamental.
This is a close-up of Saturn taken in Shenzhen, Guangdong Province on July 5, 2024. (Photo by Star Photographer Zhang Yipeng)
"Due to the difference in angular velocity of the Moon and Saturn relative to the Earth, the occultation process will only last about 1 hour." Pu Shi, a member of the Beijing Astronomical Society, said that the occurrence of lunar occultation of Saturn is related to the orbital period of the Moon and Saturn, the inclination angle of the orbit, and the receding of the yellow-white node. There is a roughly cyclical pattern, and there is a "series" every 5 or 6 years, that is, almost once a month, but it is not visible in most years. There will be 10 lunar occultations of Saturn this year, but only two will be visible on the mainland, July 25 and October 15.
The observation conditions of the lunar occultation of Saturn this time are relatively good, occurring from the early morning to sunrise of the 25th, and the occultation runs through most of the continent, and the southwest region starts first, at about 4:30 a.m. on the 25th. As the occultation moves north, the occultation begins later and later, and the sky gets brighter. In the Central Plains, the occultation begins at around 5 o'clock, not far from sunrise, and the occultation process can still be seen in the morning light. But in the Northeast, the sky was completely bright at the beginning of the occultation, but Saturn was relatively bright and could still be seen and photographed during the day with an astronomical telescope.
Pushi said that there are two disadvantages to observing the lunar occultation of Saturn: First, the inclination of Saturn's rings reached its minimum in late June this year, and in ordinary telescopes, it is expected that only a thin line on Saturn's dot can be seen. If you want to see Saturn's rings, it's best to use a large-aperture telescope.
This is Saturn and the Moon photographed on the evening of September 8, 2019 in Beijing's Xicheng District. (Photo by starry sky photographer Zheng Zhi)
Second, at the end of the occultation, it is already dawn in northern, southern, and southeastern regions of the mainland, and the moon and Saturn are likely to be submerged in the skylight. But even if you can only witness the shocking moment of the beginning, it is completely worth it.