Star of Bethlehem
Many men have tried to determine what this star was. We have tools available, which seem to be good, such as the Wolfram Alpha computational engine which is open on the internet. This particular machine (it is a software machine) can do marvellous things, including the computation of celestial bodies as they appeared thousands of years ago. However its flaw is that we must assume that as the celestial bodies are today, so they were thousands of years ago. We must bear in mind that this is indeed an assumption, and there are no guarantees that it is correct.
There are many books and papers written by men professing to know what the star was, and all for their own reasons. One thing is certain: there is apparently no Scripture today which indicates anything about it, but these magi were indeed quite confident and so they must have had something that instructed them of the start and its significance.