The first day of June is the day of the lunar calendar. On the first day of each month in the lunar calendar, the moon phase is the new moon, which is the new moon (invisible). That is, the moon and the sun are in the same direction, and there is no moon at all. Not only the first day of June, but also the first day of every month.

The new moon is an astronomical phenomenon, which refers to the situation that on the first day of each month in the lunar calendar, when the moon moves between the sun and the earth, the moon faces the earth with its shadow, rises and falls with the sun, and the moon cannot be seen on the earth.

On the first day of each month in the lunar calendar, when the moon moves between the sun and the earth, the moon faces the earth with its dark side and rises and falls with the sun, so people can't see it. At this time, the moon phase is called "new moon" or "new moon".

In astronomical terms, the new moon is the phase of the moon when it is the same as the solar ecliptic (the solar ecliptic refers to the earth's orbit around the sun), that is, the moon, the sun and the earth are on the same line.