We explore all these worlds because they are fascinating in themselves. But we also explore them to understand our own planet better -- both its past, and its future. No matter where we go in the solar system, we are reminded how precious and unique our own world is. So I'll finish this post with a view of Earth's north pole, taken a few years ago. This year, under cover of winter darkness, Earth's polar ice should be re-forming. But it isn't. Understanding all the different forces that are acting to make this year so anomalous is a difficult challenge. The insights we gain from studying the atmospheres of Venus and Mars have already contributed to our ability to predict the future of our own world. But those insights do not teach us how to accomplish the social, cultural, and political changes we need to make in order to avoid the direst predictions. For that, we need to heed other experts.