Question

If ther is no atmosphere what would happen? answer briefly..

Answer 1

Mercury's lack of atmosphere means that it is not the hottest planet; Venus, with its runaway global warming, has that honor. The temperature of Mercury varies from day to night, but the planet only changes slight during its seasons may be this answer

or

The atmosphere keeps all the oxygen and gasses inside, so when the atmosphere suddenly disappears so too will oxygen and so too will all life on Earth.

The atmosphere blocks out a whole lote of harmful radiation from the Sun so without the atmosphere the Earth’s oceans would evaporate in time.

The temperature on Earth would change drastically and we'll end up looking something like the Moon.

Last but not least asteriods and meteors. The atmosphere helps burn those space rocks before they actually hit the Earth and cause any damage.

Answer 2

if there is no atmosphere all the life from the Earth will be damage and the earth will become very dry and all the microorganisms and living beings will be killed without air...