For as Jonas was three days and three nights in the whale’s belly; so shall the Son of man be three days and three nights in the heart of the earth.
—Matthew 12:40 (AV)
On what day of the week was the Crucifixion? If it occurred on a Friday and Christ was raised from the dead on the following Sunday morning, then He was in the grave for only one day and two nights. That’s not even a close approximation of the time He predicted. It’s only half of the time specified.
When I googled “sign of Jonah” recently, the first hit was for an Islamic website that tried to use this traditional time line to prove that Jesus was not the Messiah. Was Jesus a false prophet, or is the traditional chronology of the Passion in error? Given that I believe that Jesus is the second Person of the Godhead and that one of my First Principles is that God does not lie, you should not be surprised that I believe that the traditional chronology is wrong. Moreover, I believe that many of the common assumptions about the dates of Jesus’ life and ministry don’t agree with the Biblical account.
Let’s start with when He was born.
It certainly wasn’t in late December.
That is inconsistent with the evidence in the Gospels, especially Luke:
And there were in the same country shepherds abiding in the field, keeping watch over their flock by night.
—Luke 2:8 (AV)
The Mishnah is the first written recording of the oral law as understood by the Pharisees. One section deals with the flocks destined for Temple sacrifice that were kept in the area around Bethlehem.  It states that these flocks were pastured there for the thirty days before Passover. Passover is on the 14th day of Nisan,  a month of the Jewish calendar that coincides with late March and April with the our modern calendar. If the the shepherds were the Temple shepherds who were watching over the paschal lambs, they would have been in the fields near Bethlehem some time from late February until the first weeks of spring. 
Does that fit with the other details of the Nativity story?
Yes, I think so. We know that Herod was alive when Jesus was born and that he had died when Jesus was presented in the Temple at the time of Mary’s purification sacrifice. According to Leviticus 12, that sacrifice was to occur on the the 40th day after the birth.  Josephus’ Antiquities of the Jews places Herod’s death between a Lunar eclipse in early March and Passover in April of 4 BC. Putting this all together we have Jesus’s birth in early March, a quick trip to Egypt (financed with gold, myrrh, and frankincense), Herod’s death, a quick return to Israel, and, finally, Mary’s presentation later in April. All in 40 days.
There is scientific evidence to support this dating. When the magi (astrologers, really) told Herod of the sign that led them to come to find the King of the Jews, they said, “for we have seen his star in the east.”  Herod then ordered the killing all of the boys in Bethlehem two years of age and under. Why two year olds? Perhaps it is because of what the astrologers told him they saw and when they saw it.
On 29 May, 29 September, and 6 December of 7 BC , there were conjunctions of Jupiter and Saturn. That means that these planets appeared close together in the night sky. Such triple conjunctions are rare. Nine months after the first of those conjunctions, on 25 February, 6 BC, a fourth conjunction occurred; this one of Jupiter, Saturn, and Mars. This was followed by a conjunction of Saturn and Mars in 4 BC within a week of the Lunar eclipse mentioned by Josephus. It is likely that Herod assumed that his rival was born on or after the 6 BC date which would have been just about two years before the magi showed up in Jerusalem. (Hence, the killing of male children two years old and under.)
Conjunctions as seen from the Near East. 29 May, 7 BC at 3:00 am. 29 September, 7 BC at 3:00 am. 6 December, 7 BC at 11:00 pm. 25 February, 6 BC at 6:45 pm. Jupiter and Saturn are so close in the September and December illustrations that the labels overlap.
If Jesus were born just before Passover in 4 BC, He would have turned 30 in AD 27. That fits with what we find in Luke 3 where He described as being about 30 at the beginning of His ministry.  The first verse of the chapter describes John the Baptist’s ministry as beginning in the 15th year of the reign of Tiberius. The Roman Senate named Tiberius as Emperor on 18 September, AD 14. One can count his 15th year as beginning on 25 March, 28, the beginning of the new year on the Roman civil calendar. Jesus’ ministry began after John’s, perhaps later in AD 28.
During His ministry, Jesus went to Jerusalem for four Passovers.  One would have been in 29, the next in 30, the next in 31, and the final one in 32. What day of the week was Passover in 32?
Astronomy can answer the question by plotting the phase of the moon. That year, Passover began on Tuesday evening of 15 April. That would put Jesus’ execution during the day on Wednesday and His burial late that day. By modern reckoning He was in the grave on Wednesday night, Thursday day, Thursday night, Friday day, Friday night, and Saturday day. That’s three days and three nights, just as He said. The Resurrection occurred at the beginning of the first day of the week which according to the Jewish calendar is what we call Saturday night. The Bible does not say that He rose at dawn on Sunday. It says that the tomb was found to be already empty then.
Those wedded to the traditional chronology will protest that the Bible says that Jesus had to be buried quickly because it was Friday and the Sabbath was approaching. The Bible says no such thing. What it does say is:
The Jews therefore, because it was the preparation, that the bodies should not remain upon the cross on the sabbath day, (for that sabbath day was an high day,) besought Pilate that their legs might be broken, and that they might be taken away.
—John 19:31 (AV)
We need to look back to the Law of Moses to understand the meaning of this passage.
There’s a Sabbath every week. There are also other days during the year that are Sabbaths without regard to the day of the week on which they occur. One of these is the day following Passover, or the first day of the Feast of Unleavened Bread.  Thus, Thursday was a Sabbath, Friday was spent preparing the spices to anoint the body, and Saturday as another Sabbath. When the women finally got to the tomb on Sunday, it was empty. Jesus was in His grave for three days and three nights.
This is important. It goes to the heart of the reliability of the Gospels. Here we have Science providing empirical evidence that supports the timing of the Biblical narrative if we are willing to actually read what the Scriptures say and compare that to what we find in nature.
The Good Friday tradition derives from a misunderstanding of the Scriptures, ignoring the Feast of Unleavened Bread. The AD 33 date normally given for the crucifixion comes from the fact that Passover was on Thursday night/Friday in that year.
The Islamic apologist I mentioned at the beginning of this post wouldn’t have a point to attack if we Christians had been more careful in our reading of the New Testament and in understanding it within its Jewish context. Instead, we became wrapped up in our own point of view. That’s unfortunate, but it’s human nature.
 Shekalim, vii, 4.
 Leviticus 23:5.
 If they were the Temple shepherds, then it was appropriate that they be called to watch over The Paschal Lamb.
 And in the eighth day the flesh of his foreskin shall be circumcised, And she shall then continue in the blood of her purifying three and thirty days; she shall touch no hallowed thing, nor come into the sanctuary, until the days of her purifying be fulfilled.—Leviticus 12:3, 4 (AV)
 Matthew 2:2 (AV). The “east” is not the direction they were looking. “The East,” that is, Mesopotamia, is were they were when they saw the “star.”
 These dates use the current Gregorian calendar. I could use the Roman Julian calendar or the Jewish calendar for dating, but this seems simpler. All the dates in this post use our modern calendar.
 Luke 3:23 reads, “And Jesus himself, when he began to teach, was about thirty years of age …” in the American Standard Version.
 John 2:13, John 5:1, John 6:4, and John 13:1.
 And on the fifteenth day of the same month is the feast of unleavened bread unto the LORD: seven days ye must eat unleavened bread. In the first day ye shall have an holy convocation: ye shall do no servile work therein.—Leviticus 23:6, 7 (AV)