Matthew 2:2
Saying, Where is he that is born King of the Jews? for we have seen his star in the east, and are come to worship him.
The coming of Jesus as King of the Jews was prophetic and announcing with a star in the east. The astronomers and wise men of the past followed it and knew that it signified a king was born. So they honored that and came to worship him.
They could have just observed the signs, made notes, and moved on, but they knew this was a significant world event and they wanted to be part of it and follow the protocol of the time by worshipping the king.