Radio listener by Jim Gilchrist

Happy birthday, Neptune. Not the salty old gent with the trident and seaweed in his beard, but the planet, which is one year old – one Neptunian year, we hasten to add – on Tuesday. Because this year Neptune, now recognised as the outermost planet of our solar system (since Pluto was demoted to a planetoid), has completed just one circuit of the Sun since it was discovered in 1846.

A 165-year orbit is the least of Neptune's problems. It has an atmosphere (but not as we know it, Jim) well stocked with methane, giving the planet its distinctive blue sheen.

Monday's happy birthday neptune takes a close look at the distant planet and the history of its investigation by mankind – some believe that Galileo spotted it four centuries ago, noting its existence in a coded Latin anagram. That's just one of the planet's many mysteries.

With its invigorating methane-rich winds nine times stronger than Earth's, Neptune sounds like Hell.

However, Radio 4 really goes to Hell, and not just metaphorically, when a new, 13-part series of beyond belief kicks off with Ernie Rea and his guests considering the Christian idea of Hell, and whether it is at all compatible with the Christian belief in a "loving God"?

Rea, a seasoned veteran in terms of religious broadcasting and debate, discusses the realm of fire and brimstone with the Catholic writer and commentator Peter Stanford, theology lecturer Morwenna Ludlow from Exeter University and Daniel Strange from Oak Hill Theological College, north London.

The protagonist of James Robertson's intriguing novel The Testament of Gideon Mack finds himself in Hell of a sort – immured in an underground cavern with a decidedly Mephistophelean tormentor.

In my life in five books, Robertson tells Stuart Cosgrove about his favourite volumes, including the Brewer's Dictionary of Phrase and Fable which he finds indispensable.

Robertson also talks about his time as the first writer-in-residence at Hugh MacDiarmid's cottage at Brownsbank near Biggar, and why he regards the carnaptious auld iconoclast's Selected Poems as the book that changed his life.

Happy Birthday, Neptune

Monday, Radio 4, 11am

Beyond Belief

Monday, Radio 4, 4:30pm

My Life in Five Books

Thursday, Radio Scotland, 2.05pm

This article was first published in The Scotsman, 9 July, 2011