Why did the sky go black when Jesus died?

And when the sixth hour was come, there was darkness over the whole land until the ninth hour.

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? [Mark 15:32–34].

"I want you to notice here that Mark gives us the Crucifixion by the clock. On the third hour He was put on the cross, and at the sixth hour (which would be twelve noon) darkness came down. The high noon sun was covered, and darkness came down over the cross. From the sixth hour to the ninth hour, that would be until three o’clock in the afternoon, there was darkness.

Now will you notice this: the first three hours were from 9:00 A.M. until 12 noon; the second three hours were from 12 noon to 3:00 P.M. Jesus hung on the cross for six hours. In the first three hours there was physical light; in the second three hours there was physical darkness. But in the first three hours there was spiritual darkness; in the second three hours there was spiritual light. Why? Because in those first three hours man did his worst. They crucified Him and they reviled Him. Even those who were hanging with Him on the cross reviled Him. At least at the first, both thieves did. At that time the enemy, marching around down beneath the cross, were wagging their heads and ridiculing Him. In the first three hours man was working, doing his very worst; in the second three hours God was working. He was suffering at the hands of man in the first three hours; He was suffering for man in the last three hours. In the first three hours He was dying because of sin; in the second three hours He was dying for the sin of the world. So during the time of the physical darkness, there was actually spiritual light and God was working. In those first three hours sin was doing all it could to destroy Him; in the second three hours He is making His soul an offering for sin. In those last three hours He is paying for the sins of the world. It was during this period that He was made sin for us; He became sin for us. He was forsaken of God and vet. even at that time. God was in Christ, reconciling the world unto Himself (see 2 Cor. 5:19). What a paradox we find here." McGee, J. Vernon: Thru the Bible Commentary. electronic ed. Nashville : Thomas Nelson, 1997, c1981, S. 4:232

Response to comment [from a Christian]:  "Why did Jesus prayed drops of blood before dying?"

And being in an agony he prayed more earnestly: and his sweat was as it were great drops of blood falling down to the ground [Luke 22:44].

"Only Dr. Luke tells us that the Lord sweat great drops of blood. The Lord showed a tremendous physical reaction to the agony and conflict that confronted Him. I cannot explain what happened and do not propose to try. I am not, however, impressed by the biological explanations offered today. I realize there are some wonderful Christian doctors that have come up with some interesting explanations, but I still am not impressed. He shed His blood for me and I bow in reverence and worship.

But none of the ransomed ever knew
How deep were the waters crossed,
Nor how dark was the night that the Lord
passed through,
Ere He found His sheep that was lost:
From “The Ninety and Nine”—Elizabeth C. Clephane

...Christ’s heart was broken because of our lost condition. He bled and died for our eternal liberty. He said, “… I am come that they might have life, and that they might have it more abundantly” (John 10:10). He loved a lost world so much that He went to the very depths of hell itself to offer it salvation. And the world spurns the Holy One of God, the spotless Savior who was made sin for us. Let me ask you a question. Have you rejected Him? Have you spurned Him? Are you ungrateful for what He did for you?

Stand in the hush of Gethsemane and listen. Do you hear the sob of His soul? Do you hear the falling drops of blood? Look yonder in the garden by an olive tree and see, bending low in agonizing prayer, the Savior who took upon Himself your humanity and mine. The next day He went to the cross." McGee, J. Vernon: Thru the Bible Commentary. electronic ed. Nashville : Thomas Nelson, 1997, c1981, S. 4:348-349

...The earth was shaking in the dark
All creation felt the Fathers broken heart
tears were filling heaven's eyes
The day that true love died, the day that true love died
When blood and water hit the ground
Walls we couldn't move came crashing down
We were free and made alive
The day that true love died, The day that true love died...

--True Love lyrics by Phil Whickham

"Why are women in the Bible, too?"

To make the samiches (Ge 18:6).  

"...[D]oes the six hours relate to the six days of creation?"

Six in the number of man. Beyond that, I could only speculate.

See:

Meaning of Numbers (6)

Numbers in the Bible

"Is there a connection between the blood and the darkness?"

We cannot comprehend his suffering (Ps 97:2). I'm not sure.

See:

Darkness
Blood

[Samiches] "Find a girl to make me samiches..."

If you've found a girl who will make you samiches, you've found a good thing (Pr 18:22)."

Response to comment [from other]:  [Suicide] "Planning your own death is suicide."

The Jews asked that.

Then said the Jews, Will he kill himself? because he saith. Whither I go, ye cannot come [John 8:20–22].

"The treasury was in the women’s court. This was where they had brought the woman taken in adultery. You will notice how much these Jews were in the dark. First they ask, “Where is thy Father?” Now they ask, “Will he kill himself?” They know nothing about the fact that He has been instructing His own that He is going to Jerusalem to die at the hands of the Gentiles, that He will be delivered up to die by these very same religious rulers, and that He will die a redemptive death for the sins of the world. Will He kill Himself? No! He will give Himself a ransom for many."
McGee, J. Vernon: Thru the Bible Commentary. electronic ed. Nashville : Thomas Nelson, 1997, c1981, S. 4:418

Murder of self is forbidden (Ex. 20:13). Jesus gave his life (Mt 20:28).

Therefore doth my Father love me, because I lay down my life, that I might take it again.

No man taketh it from me, but I lay it down of myself. I have power to lay it down, and I have power to take it again. This commandment have I received of my Father [John 10:17–18].

"He says that all of this is the will of the Father. The Father loves Him because He died for us. We also ought to love Him because He died for us. He made His soul an offering for sin. On the cross during those three hours of darkness, God the Father put upon Him the sin of the world, and He went through hell for you and me. The Good Shepherd gave His life for the sheep.

He makes it very clear that He gave His life willingly. He was in full control at His trial. Also He set the time of His death. The Jews said it shouldn’t be on a feast day lest there be an uproar, a riot, of the people, but He was crucified on the feast day. He was never more kingly than when He went to the cross. If one reads the Gospels carefully, one is aware that actually the Roman government was on trial, the nation Israel was on trial, you and I were on trial. Although He didn’t have to die, He did it willingly for the sins of the world. “Looking unto Jesus the author and finisher of our faith; who for the joy that was set before him endured the cross, despising the shame …” (Heb. 12:2). No man could take His life from Him. He claimed power to lay down His life and to take it again."
McGee, J. Vernon: Thru the Bible Commentary. electronic ed. Nashville : Thomas Nelson, 1997, c1981, S. 4:432

Response to comment [from :  "Time and date of eclipse..."

How 'bout that birth?

[An excerpt: The Star of Bethlehem: An Astronomical Perspective] "...[A] very close pairing of Venus and Jupiter in Leo that occurred around 2 B.C.E. in which the planets seemed to merge as seen with the naked eye (no telescopes back then!)..." Full text: The Star of Bethlehem: An Astronomical Perspective

Why did the sky go black when Jesus died?