Will not the sign of the Son of man in heaven be more than positions of planets, stars, and the moon?

Matthew 24:30 And then shall appear the sign of the Son of man in heaven: and then shall all the tribes of the earth mourn, and they shall see the Son of man coming in the clouds of heaven with power and great glory.

After the 2012 signs in the heavens, all the tribes of the earth were not mourning.

In fact, most of us, unless we read an article on the web, or saw a YouTube video, really had no clear idea about it, prior to that.

So how much less all the tribes of the earth?

Also, will not the sign of the Son of man in heaven be more than clouds, or light, forming the shape of a cross, like Constantine saw?

Why are all the tribes of the earth mourning?

Will they not all then know that this is about Jesus?

Will they mourn because they know that they are in trouble, and that time is up?

Will they mourn because they had never repented and believed on Jesus?