The Crucifixion of Christ was on Thursday, because he was in the tomb 3 days and 3 nights.
Christ was not crucified on Friday, but on Thursday; the traditional interpretation that assures Christ was crucified on a Friday is false.
One day is composed of a period of darkness (night), and a period of light (day). We must remember that the Hebrews would count days starting at the break of nighttime. For them, the day would end at nightfall but as soon as the stars would come out, it would mark the beginning of a new day. That moment began the period of darkness, or the nighttime of the following day. Later, at the break of dawn, is when the period of light would begin for the day that begun the previous night.
Here it says that Jonah stayed in a whale's belly, and Jesus in the heart of the earth, for three days and three nights respectively. Give or take a few hours and that is roughly 72 hours. But not 12 hours less, or 12 hours more.
"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. (Mt 12:40)
If we read the case of Jonah, we will also see that it specifically states that Jonah was in the belly of the fish three days and three nights.
"Now the LORD had prepared a great fish to swallow up Jonah. And Jonah was in the belly of the fish three days and three nights. (Jon 2:1)
By what we read in Mathew 12:40, we can be assured that at the very least Jesus spent some hours in the period of light, and some hours in the period of darkness on the first and last days on the crucifixion. It's to say that even though it doesn't add up to exactly 72 hours, Jesus was in the heart of the earth, as a minimum, part of the first initial period of light and part of the final period of darkness. There is no doubt whatsoever that he participated in all six halves of the day: three periods of daytime and three periods of nighttime. Therefore, this verse makes me think that Jesus was crucified on Thursday, somewhere around 9 o'clock AM, and died around 3 o'clock PM that same Thursday.
Let's make a diagram representing each period of darkness and each period of light. Let's represent the moment of his death with a "D" and the moment of his resurrection with an "R". The time in between the "D" and the "R" is the time Jesus was in the heart of the earth.
___D__ _________ __________ _________ _______ ________R_ ________
Thu day Fri night Fri day Sat night Sat day Sun night Sun day
As we can see graphically, in the case I try to make, Christ was in the heart of the earth for at least part of Thursday, all night on Friday, all day on Friday, all night on Saturday, all day on Saturday, and at least in part on Sunday night, resurrecting before the period of light on Sunday.
In the case that we all accept the 3 days and 3 nights, which is what the Lord says, the most you could allege on the contrary is that part of the day in one of both extremes (Thursday) he wasn't dead, but at least part of the day (Thursday) he was in the heart of the earth. The same can be said with the night of the other extreme (Sunday); it could be that he wasn't in the heart of the earth on the final part of Sunday night, but at least he was dead in the period of darkness on Sunday, before the break of dawn. This tells us that Christ could not have been crucified on Friday, but on Thursday.
Now let's look at another diagram from a different point of view. The same issue, but this time as it is traditionally taught, assuming the crucifixion was on Friday.
______D__ ____________ __________ __________R___ ____________
Fri day Sat night Sat day Sun night Sun day
As you can see, if we adopted the traditional teachings, there is no way Jesus could have been in the heart of the earth for 3 days and 3 nights. The maximum amount of time he could have spent was 2 days and 2 nights. This doesn't match with what was said by the Lord, who was very specific and clear. Therefore, the argument concerning Jesus' crucifixion on Friday can simply not be true.
Concerning what I said on Christ being crucified at 9 in the morning and dying around 3 in the afternoon, to say such a thing, I base myself on Mr 15:25 and 34-37. Keep in mind that they counted the 12 light hours of the day, starting at the break of day, in other words starting at what we would call 6 in the morning; and the watchers of the night were counted at nightfall. Therefore, what they called 3 were what today we call 9 in the morning, and what they called 9 was actually three in the afternoon.
"And it was the third hour, and they crucified him." (Mrk 15:25)
"34 And at the ninth hour Jesus cried with a loud voice, saying: Eloi, Eloi, lama sabachthani? Which is, being interpreted, My God, my God, why hast thou forsaken me? 35 And some of them that stood by, when they heard it, said: Behold, he calleth Elias. 36 And one ran and filled a spunge full of vinegar, and put it on a reed, and gave him to drink, saying, Let alone; let us see whether Elias will come to take him down. 37 And Jesus cried with a loud voice, and gave up the ghost. (Mrk 15:34-37)
The Traditions aren't bad in themselves, bad is when the tradition substitutes the Scriptures. Anytime a tradition isn't rejected by the Bible or common sense, it can be accepted; but when the bible contradicts the tradition, it should be rejected. That's why it's good to read the Bible on a daily basis, in order, without skipping, starting with Genesis, finishing with Revelation, and starting back again with Genesis. We should do this while we still live, without thinking that we've read it all or read it enough. Every so often new difficulties arise that need to be analyzed. It's only by reading the entire Bible one more time that we'll resolve any arguments or difficulties along the way.