Home Planet - 07/07/2009

Home Planet returns to Radio 4 with answers to another selection of your questions. How do we know how old the Earth is? Why are there no penguins at the North Pole? How do earthworms get into elevated compost bins? Why are there no green mammals? Plus a proposal that we should harvest and eat insect swarms. Answering these questions are science writer Dr Lynn Dicks, ornithologist Graham Appleton, and environment scientist Professor Philip Stott. As always we want to hear your comments on the topics discussed and any questions you might want addressed in future programmes. We would like your help in surveying the British house martin population. The British Trust for Ornithology is conducting a house martin survey, and we are also asking listeners for their experiences with these charming summer visitors. Please let us know your sightings and observations by clicking the 'contact us' link.