Hanukkah is beginning on the same day as Christmas for the first time since 2005. Here's why it doesn't happen often.

According to VOX, the holidays don't align very often. The two dates randomly align because the Jewish and Gregorian calendars don't align. Since 1900, the first day of Hanukkah has fallen on Christmas only four times:

Though Christmas and Hanukkah rarely fall on the same date, Hanukkah this year begins Christmas Day, which is Wednesday, Dec. 25. This hasn't happened since 2005. According to chabad.org, Hanukkah is an eight-day celebration for those who celebrate in the Jewish community.