What is the “Moon Covering Subaru Star Cluster”?
Why does the moon cover the Pleiades star cluster?
- 1. The regularity of celestial motion: The orbit of the Moon around the Earth (the White Way) is close to the orbit of the Earth around the Sun (the ecliptic), and the Pleiades star cluster happens to be located near the ecliptic. Therefore, the Moon passes near the Pleiades star cluster every month, forming a “companion moon” or “occultation” phenomenon.
- 2. Perspective coincidence: Due to the positional relationship between the Earth, the Moon, and the Pleiades star cluster, when the three are connected in a line, the Moon will block the starlight of the Pleiades star cluster, forming an occultation phenomenon.
The period and uniqueness of the Moon covered Pleiades star cluster
- Periodicity: The moon approaches the Pleiades star cluster every month, but whether it can form an occultation depends on the latitude, longitude, and lunar phase of the observation site. For example, in 2025, China will observe the Pleiades star cluster four times (on March 5th, August 16th, November 6th, and December 31st), with the best observation conditions on March 5th.
- Specificity: The moon phase on March 5th is close to the first quarter moon, with low brightness. The Pleiades star cluster is less affected by moonlight interference and can be seen in most parts of China. The observation effect is better the further north.“Among the four lunar occultations of the Pleiades star cluster this year, this one has the smallest lunar phase. Interested members of the public can try to observe and photograph it with a small astronomical telescope Yang Jing, a member of the Chinese Astronomical Society and a director of the Tianjin Astronomical Society, said. On the evening of March 5th, interested members of the public can bring their binoculars and invite three to five friends to participate in this starry sky event! “
