“Our Place in the Cosmos” is a planetarium show about the special, fragile place of the Earth in our Galaxy, the only habitat we yet know able to sustain life.
Our home needs to be in the right place of our Galaxy to be safe from violent activity like supernovae. Yet we needed such activity in the past for the elements that support life, produced inside stars, to be seeded in the proto-solar nebula from which the Earth formed.
Our home also needs to be in the right place of the Solar System to be in its habitable zone, a place capable of sustaining liquid water its surface for eons. We compare Earth to our nearest planetary neighbours, Venus and Mars, which also began their lives in the habitable zone. Soon after their birth, over 4 billion years ago, these three planets looked similar – rocky worlds with flowing lava and water under an atmosphere.
Yet their subsequent evolution followed very different paths. Venus turned into a Hades, the oceans boiling away to create a thick, hot toxic atmosphere. Mars lost its atmosphere and the oceans evaporated into space, to leave a dead world, yet where evidence of past liquid flows is still apparent.
We illustrate these contrasts in the show, we delve beneath the atmospheres to show how oceans might have looked on Venus and Mars. We contrast them to the Earth, and we show what would happen to our continents should sea level rise.
Finally, we show Planet Earth today and see how we can monitor planetary health from space, providing a global view of the land, oceans and atmosphere. We see how fragile planet Earth is and the imperative to protect our home from further damage.