what model cyber shot?
does it have a manual mode?
can you adjust the ISO?
do you have a tripod?
If your camera does not have a manual mode you will have a tough time achieving specific effects with you pictures. You may be able to change the metering mode (the way the camera evaluates the highlight and shadows in the picture to determine the exposure).
Adjusting the ISO will effect the amount of grain in the pictures. From what you describe, it seems your camera is automatically adjusting the ISO depending on light conditions. A low ISO (i.e. 200) produces less grain but is less sensitive to light. A a high ISO (i.e. 1600) will produce much more grain but is more sensitive to light.
A tripod is absolutely necessary for long exposures.
I like the last picture of Sentinel. Even thought the highlights are blown out the glowy effect is pretty cool. Don't be afraid to crop in tight as well. Picture #2 with the same exact lighting may have more impact if you could not see the highlighted line where the shoulder ends. Since you can't see the base anyway, crop all the way in and focus on the face. It's the focal point anyway.
Have fun, rest up, heal and don't eat too many of those pills