What she does is she lifts up her body on her knees, then her toes: so she looks ready to do a push up , but she's all the way up on her toes. Then she leans forward and kinda belly-flops, leans down to move forward, then lifts herself up & does it again. It reminds me of, well, a baby seal really.
(Aurora has discovered that if Athena is trying to grab her toy or book, if she rolls Athena over onto her back, it slows her down: somewhat like a turtle in that, as she has to roll back over to get her technique up & going again: so I've caught Aurora kinda subtly rolling her sister over a few times to slow her down, it's cute in a kinda.. er, well, it's interesting how while Aurora is generally so encouraging and supportive of Athena, occassionally she too wants her to slow down a bit, and has found a subtle way to do so).
I remember how Aurora learned to crawl: instead of this seal-like push up & roll forward, Aurora came up with a very frog like move, which involved crouching up her rear legs, wiggling and hopping her hands forward by pushing w/her legs. Athena's basically taken the opposite approach: using her arms to push & pull the rest of herself forward.
Co-ordination is an amazing thing.