Gravity

Why is it that gravity allows a giant plane to float through the sky but it won't allow my child's head to stay off the ground? I'm the first one to admit that Reese has a gynormo head but it's still really sad to watch gravity punish her for it. When she was learning to sit up she'd be doing great until she turned to look at something and that huge head would mess up her balance and send her to the ground. Well today gravity decided to punish my child yet again for something she has no control over. We were at the playground and there was a little step from the grass up to the cement to walk to another area so Reese had her hands and feet both on the ground with her butt in the air as she maneuvered this step, her head couldn't have been more than 4 or 5 inches off the ground and then all of the sudden it was as if gravity remembered that her head was too big to be in the air and it yanked her back down. I wish I had video because it was a phenomenon no doubt, the rest of her body didn't even move but somehow her head smacked into the cement like it was being pulled down by a magnet. Lucky for her she has a hard head so she cried about it for all of 30 seconds and then moved on to what she was doing, but gravity still left a pretty nasty mark on that litttle angel face.