Wha happens to the weight of astronauts when they are in orbit

Microgravity. It is sometimes called zero - gravity, but this is wrong. What happens is they go into free fall. On earth, gravity causes all things to fall, it can essentially be called a 'vacuum' if you will. So, I'm not to sure about it, but that's kind of what happens.

That depends on the size of the orbit.

In "low Earth orbit", like the Mercury, Gemini, early Apollo flights, and aboard the ISS, the astronauts' weight is about 85% of their weight when they're standing on the Earth's surface.

BUT ... since everything in orbit is in "free fall", they don't feel the weight of their own body or anything else. The feeling is like being completely without any weight.