Why leaves go brown

I have to say that the onset of autumn not only turns trees golden, but also sets something off in my body clock. I become all lethargic (like I should soon be dropping into hibernation like the hedgehogs), and crave warmth (the shower notch gets cranked up a few points).  I feel like drinking mulled wine every night and find myself wishing I could buy firework-scented incenses. I think it’s plant life that sends my body in seasonal overdrive, perhaps a 6th sense.

I always wondered what it was that made leaves change colour and my question was answered on autumn watch. So I shall share my bit of science for the week with you all, and will know that you’ve learnt something new today.

Autumn leaves catching the evening sun
Autumn leaves catching the evening sun

You may have heard of a beautiful thing called photosynthesis. Funnily enough I only know how to spell this word because of my best friend in year 3. I asked him what his favourite word was, and he responded plainly it was ‘photosynthesis – duh!’ All I can say is it was way beyond my vocabulary back then! Now I know that photosynthesis is a chemical reaction between carbon dioxide, water and sunlight aided by chlorophyll that produces glucose and oxygen. It’s this very chlorophyll that give leaves their green colour.

As winter approaches, the days get shorted and less light is available for photosynthesis. The plant, recognising this, packs up for winter and the chlorophyll breaks down and isn’t regenerated. The remaining pigments in the plant (carotenoids and anthocyanins), that are usually hidden by the dominant chlorophyll, are revealed, adorning the landscape with nature’s autumn canvas.

Each species has a different trigger as to when they suck out the chlorophyll and turn their leaves ruby red and therefore, the landscape is speckled not only with different stages autumn but also with different palettes of colour as every species has its own special tint. All bow down to Mother Nature…

And the winner is…

A couple of weeks ago, I was asked to be a judge on a photography competition – all photographers where scientists, documenting their work.

There were over 150 images to view judge and only five categories. Some had documented some incredible breakthroughs in science whilst others had presented a series of beautiful images and finding that balance between the two was tough but I think we chose wel…

The competition featured in the Guardian and the full set of images can be found on flickr.


Paul May - March of the TriffidsPaul May – March of the Triffids

Carbon nanotubes are tiny tubular cylinders of carbon atoms with extraordinarily mechanical, electrical, thermal, optical and chemical properties. In their lab University of Bristol researchers are making these nanotubes even more special by putting a coating of diamond onto them.


Rachel Pallan EPSRCRachel Pallan – The finer details of life

We are a nation intrigued by body image, but do we really know what we look like on the inside? This is a section through the socket of a human hip joint showing multiple tissues merging and working together. Different types of collagen at different stages of formation can be seen in the exterior soft tissues, while porous bone provides structure in the bottom of the image.

EPSRC Jonathan RickardJonathan Rickard – We all fall down

Thin films are ubiquitous, both in nature and in the man-made world. When we blink, tears form a film which spreads over the eye, making the surface smooth and optically clear and enabling good vision.

University of Birmingham researchers are exploring an alternative way to form thin-film-based structures by using strong electric fields, which induce electrohydrodynamic (EHD) instabilities. The EHD technique is more practical, reliable and robust than conventional techniques, and enables the precise control of the way the film destabilises – crucial to the production process.