"It has been said that astronomy is a humbling and character-building experience. There is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world. To me, it underscores our responsibility to deal more kindly with one another, and to preserve and cherish the pale blue dot, the only home we've ever known."
- Carl Sagan
It was just over 20 years ago that the famous "pale blue dot" image was captured by Voyager 1. In this image, Earth is a tiny speck, barely visible unless you know where to look. For the first time, we were able to see how Earth looks from afar: impossibly small. But, small as Earth may be in comparison to the solar system, it has enabled humankind to make our mark within the cosmos. It gave life the conditions it needed to develop enough to the point that today, we have the capability to send spacecraft to the planet next door or the edge of the solar system, and put telescopes in orbit that search for other worlds. And, despite the thousands of recently discovered planets, it is likely the only home we will ever know.
Over the last 5-10 years, we have drastically increased the number of known planets outside the solar system. Owing in large part to the success of the Kepler mission, this has dramatically changed our view on the uniqueness of Earth, and our place in the cosmos. Just last week it was announced that astronomers had discovered the first Earth-mass planet in the habitable zone of its host star. If this wasn't enough to convince you that Earth-like planets aren't particularly rare, the various Mars rovers and orbiters continue to turn up evidence that water used to flow freely on the Martian surface. But, as we continue to explore worlds in our solar system and discover new ones tens or hundreds of light years away, we should always keep an eye towards our own pale blue dot. Sagan spoke of preserving and cherishing Earth - something that feels even more relevant today given the reality of climate change. In a galaxy full of small rocky planets, this is the only one we have the opportunity to nurture and protect.