What would it be like on Earth if the Solar System went through a dense cloud of interstellar gas?

Question

What would it be like on Earth if the Solar System went through a dense cloud of interstellar gas?

Answer 1

Exactly *** all would happen. A "dense cloud of interstellar gas" is of density 100 atoms per cubic centimeter: a better vacuum than can be produced on Earth. And all of that would be prevented from entering the solar system by the solar wind, which is of higher density and pressure.

Answer 2

URRRPPP! Excuse me!

Answer 3

A couple of things could happen.

If the gas was dense enough, it could block some of the sunlight reaching Earth, meaning the Earth would cool down, possibly enough to cause a global ice age (it wouldn't take much, a few degrees lower temperature for a few months could trigger ice advance.

The Earth's gravity would attract and capture some of the gas, increasing the air pressure on Earth.  If the gas was hydrogen (the most likely element in a gas cloud), then it would rather quickly escape back into space (Earth's gravity isn't strong enough to hold hydrogen long).

This wouldn't affect the Earth much over time.

However the hydrogen could combine with high-altitude elements such as oxygen (to form water), carbon (to form methane) or nitrogen (to form ammonia) - these would dissipate rather quickly, since solar radiation will ionize these compounds back into the base elements.