Sensitive radio observations towards young stars can detect not only jets but also dust emission from a circumstellar disc. A reservoir of large dust grains is a sign that larger bodies are accumulating, on the road to planets. A 1-cm survey with the Green Bank Telescope shows that a number of discs in the Taurus and Ophiuchus star-forming regions have such signs of dust growth and so may be called 'proto-planetary'. Inclusion of the largest grains -which dominate the mass -boosts more discs

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... o the regime of the Minimum Mass Solar Nebula, so future systems of gas giant planets are expected. The next step is to observe the discs with high resolution to see if the grain growth occurs in the regions at a few AU where planetary cores should form -eMERLIN will be very effective for this, and a Legacy survey is planned. Sample calculations show that even the zone of terrestrial planet formation could be detected and resolved. From planets to dark energy: the modern radio universe