Why is there no water on mercury?

Because mercury is very close to the sun, its surface temperature during the day can be as high as 427℃; It drops to-173℃ at night. Because the surface temperature of mercury is too high, it can't maintain a dense atmosphere like its two neighbors Venus and Earth, so the sky of mercury is dark day and night. Bright Venus and Earth can be seen in the dark sky of Mercury. Mercury's extremely thin atmosphere is mainly composed of gas captured from the solar wind, and its density is only 12% of the earth's atmosphere. The main components are helium (42%), vaporized sodium (42%) and oxygen (15%). The rocks on the surface of Mercury absorb a lot of sunlight with a reflectivity of only 8%, so Mercury is one of the darkest planets in the solar system. Average surface temperature:179℃; Maximum surface temperature: 427℃; Minimum surface temperature:-173℃. There is no liquid water on Mercury, but a bright spot was observed in its Arctic region in 199 1 year. It is speculated that this bright spot may be caused by the reflection of sunlight by ice stored on the surface or underground of Mercury.