What happens if sun is not present?

Answer 1

You mean, if it is permanently gone, as though it vanished?

You know how it gets colder at night, and warmer during the day? If the sun were to disappear, it would continue to get colder and colder. The stars would shine very bright. The earth would continue to spin, but it would no longer orbit the sun. You would see stars day and night, but the moon would go dark. You would only notice it as the stars behind it disappeared from view.

Within a few days it would be really cold, and the rivers would freeze. Within a few weeks most lakes would be frozen over, and within a few months even the ocean surface would begin to solidify. There would also be no more years, no more seasons. The stars would not change position from season to season.

Answer 2

If the sun were not present, Earth would not receive the heat and light necessary to sustain life. Temperatures would drop significantly, leading to freezing conditions and eventual extinction of most forms of life on Earth. Additionally, without the sun's gravity holding planets in orbit, the solar system would be thrown into chaos.