Don’t you love Professor Brian Cox, the boyishly handsome, ex-rock star who is now a renowned physicist?

I studied physics at school and even took a unit in my first year at university but my understanding of the subject has diminished over the years.

Hardly any knowledge of physics remains but I give an occasional nod of recognition when watching Professor Cox’s documentaries on television.

This winter I am perplexed by an intriguing physics phenomenon in my garden.

I rescued an old fish tank from my local tip and made it into this terrarium.

It stands on two unturned pots from K-Mart, a favourite inexpensive hunting ground of mine.

My greatest outlay was the piece of perspex I had cut to act as a cover. I tried recycling old picture and window frames but they let the rain in, so perspex it was.

I spotted the red fish tank ornaments when visiting a local pet shop, they complement the prevailing Asian theme of my garden and are just the right size.

Luckily I also found these unusual rocks in the pet shop and they fit perfectly.

The terrarium keeps my delicate plants warm over winter.

However, an odd phenomenon occasionally happens. On dull days the terrarium glows as if a fluorescent light is switched on inside. It’s truly amazing.

Interior condensation seems to intensify the winter light shining into the terrarium.

My physics is so sketchy I don’t understand what is happening. Is it dispersion, refraction or perhaps polarization of the light?

Now, let me see if I can find Professor Brian Cox’s website. I will email him and ask.

JT