Australia’s Science Minister, Senator Kim Carr, is sending an interstellar text message to the planet Gliese 581d. It’s 20.3 light years from Earth – that’s 119 trillion miles – and it’s believed to be the closest Earth-like planet that could support life. His message, which marks the country’s National Science Week, said: “Hello from Australia on the planet we call Earth. These messages express our people’s dreams for the future. We want to share those dreams with you.”