IHF wrote:it happens approx every 2 to 3 years and it also marks the beginning of the muslim new year.

So Muslims only have a new year every 2 to 3 years?
"Quote: Al-Hijra, the Islamic New Year, is celebrated on the first day of Muharram, the month in which Muhammad emigrated from Mecca to Medina in 622 CE (the Hijra). The holiday is also known simply as Muharram. Islamic years are calculated from 1 Muharram, 622 CE. They are followed by the suffix AH, which stands for "After Hijira" or Anno Higirae (Latin). In 2005, Al-Hijra falls on February 10, 2005, which will be 1426 AH.
Unlike the important holidays of Eid al-Fitr and Eid al-Adha, there are few rituals associated with Islamic New Year. There are no prescribed religious observances. Most Muslims regard the day as a time for reflection on the Hijira and on the year to come. In modern times, some Muslism exchange greeting cards to celebrate the holiday."
You may be getting confused with Ramadan, or Eid-Al-Fitr which is one of the major holidays of Islam. It comes at the end of the holy month of Ramadan and celebrates the end of the fasting, and depends on the sighting of a new moon. It has nothing to do with the alignment of the planets.