Risks to humans and the Earth:- The concept is expressed in various phrases such as “End of the World“, “Doomsday“, “Ragnarök“, “Judgment Day“, “Armageddon“, “the Apocalypse“, “Yawm al-Qiyāmah” and others. (પ્રલય, કયામત )
1–Solar flares, supernovae, black hole explosions or mergers, gamma-ray bursts, galactic center outbursts, buildup of air pollution, gradual loss of human fertility,
2–Distant future : The Andromeda Galaxy is on a collision course with the Milky Way.. This merging could eject the solar system in a more eccentric orbit and an unwanted position in the merged galaxy causing our planet to become uninhabitable.The Earth would finally be destroyed by tidal forces.
3– Meteorite impact : If such an object struck Earth , humanity would be completely destroyed; for this to occur the asteroid would need to be at least 1km in diameter,
7- Megatsunami : A megatsunami could have astronomical origins as well, such as an asteroid impact in an ocean.
8- Climate change and global warming :- Ice age –
9- Ecological disaster
10- World population and agricultural crisis
12- Humanity: Some threats for humanity come from humanity itself.
(b) Artificial intelligence :. Physical scientists might accidentally create a device that could destroy the earth and the solar system. such as Large Hadron Collider. Out of control self replicating robots consume all living matter on earth.
15- Historical fictional scenarios : 1- Sir Isaac Newton (1642–1727) studied old texts and surmised that the end of the world would happen no earlier than 2060, although he was reluctant to put an exact date on it. 2- The belief that the Mayan civilization‘s Long Count calendar ends abruptly on December 21, 2012, is a sign of end of the world.
16:- I also add, mankind’s own stupidity as one of the possible reason for its own destruction.
17:- As many believe, God has created this universe and life, He just may want to destroy it for reasons known to him only.
18:- Also, God’s arch rival The Devil, one day may win an eternal war with the God and either destroy this planet or just may make the humanity his slave and allow them to live. However their existence is a debatable issue.