Luke 23:44f says:

It was now about the sixth hour, and darkness fell over the whole land until the ninth hour, because the sun was obscured; and the veil of the temple was torn in two. (NASB)

The popular naturalistic explanation for that is an eclipse. The sun was obscured by the moon, obviously. Dr Ehrman also hints at that in his “The New Testament” text in chapter 9 on the Gospel of Luke.

That explanation is, of course, totally wrong and somewhat hilarious. The Jews use a lunar calendar to determine their festivals, and Passover is no different.

From Wikipedia:

Passover begins on the 15th day of the month of Nisan, which corresponds to the full moon of Nisan, the first month of the Hebrew calendar, in accordance with the Hebrew Bible.

Now, an eclipse during a full moon is truly a miracle, even for the anti-supernatural standard applied to the Bible by mainline scholars.

Examining the historical Jesus in the synoptic gospels was an assignment in a religious studies class I am currently taking. It may be useful for your own studies and point to you more resources based on my bibliography.

From the introduction:

As any careful reader of the NT gospels will notice, Mark, Matthew, and Luke have striking similarities as well as significant differences. Each gospel has a different emphasis, a slightly different order of events, and a different target audiences. Each portrays Jesus in a different role. Therefore the first question is how are the accounts of the synoptics different? What are the differences, and what picture of Jesus can be gathered from each? Next, what does the result mean for the study of the historical Jesus? Is it important, and if so, why?

The Historical Jesus