They meet at a gathering every moon to share news in the Clans and sort out things that affect more than one Clan, like territory boundaries, where their hunting grounds are etc. but the most important reason is that the full moon is the only times the Clans are peaceful and act peacefully towards each other. Gatherings give them some sort of common ground, and allow them to make friends in other Clans. Don't you think that if they didn't have some sort of temporary peace they would tear each other apart?
EDIT: They meet at every full moon because when the moon is full StarClan is watching over them for sure, if the clouds cover the moon that means StarClan is angry.
In the forest territory: Fourtrees Lake territory: Island
To discuss issues with prey, borderlines, new apprentices/kits/warriors/leaders, basically everything that humans would in that situation. It is also a time when all the cats from all the Clans can meet together without tension.
As of "Sign of the Moon," approximately two years have passed in the Warrior Cats series timeline.
Medicine cats meet at the half-moon. This is when they gather at the Moonstone or Moonpool to share dreams and receive messages from StarClan.
April 5 2011
Definitely. In the eyes of the warrior cats, Star Clan is everything. Star Clan are the ancient cats of the four Clans. They are the ones who guide them, warn them when danger is around, and tell them of the prophecies. The closest cats to Star Clan are the medicine cats, who meet at the Moon Pool every HalfMoon. The second closest are probably the clan leaders, or the ones in which are named in the prophecies.
The reason is that there are actually two half-moons between each gathering. One when the moon is waning (getting smaller), and one when it is waxing (getting bigger). Another possible reason is that on the new moon there would be no light from the moon to light up the moonstone (or moonpool).
Yes, Sign of the Moon was released on April 5, 2011.
They meet for a Gathering where they share news and meet friends from other Clans.
If you are asking about Warrior Cats Omen of the Stars #4 then it is about Lionblaze Jayfeather and Dovepaw (Dovewing). The three prophesied cats going to the "Tribe of the Rushing Water" to find out what lies in the past and finding out much more such as another prophecy.
In the Warriors series, one moon is equivalent to approximately one month in the real world. On average, warrior cats can live for around 6-10 years, which means they can live for approximately 72-120 moons. However, some cats in the series have lived longer or shorter lives.
The next book in the Warriors series after Night Whispers is Sign of the Moon. It is the fourth book in the fourth series called Omen of the Stars, following the adventures of the warrior cats as they uncover prophecies and face new challenges.