As the disciples Jesus asked: "what will be the signs of your second coming and when should all things be completed?", Jesus gave them an answer, a precise answer, and more than that He gave them a list of signs. Jesus speaks of signs on earth and He also speaks of signs in the heavens - in the sun, the moon and the stars - how God uses His creation to speak to us - the bloodmoons.
Here is an interesting graphic in English:
For more information about the end times in the Christian-biblical focus: