Ramblings Radio 4, 3pm

It may feel like she's barely had time to take her walking boots off, but Clare

Balding (right) is back for a new series. She joins author and artist

Oliver Jeffers in

Londonderry to check out a six-mile sculpture trail based on a scale model of the solar system.

In The Forum (BBC World Service, 10am & 12 midnight) Bridget Kendall examines the life and legacy of German chemist Fritz Haber, whose work helped to feed people around the world but also paved the way for the introduction of chemical warfare.

FreeThinking (Radio 3, 10pm) hosts a discussion on the work of the Russian writer and translator Isaac Babel.