A case for stargazing

The Earth spins within the cosmos...

“Better to be the Astronaut than the Astronomer…”

Everyone, I’m sure, would rather go to the stars than sit at home and study them, but few of us will ever get that chance (unless space tourism can get off the ground).

The BBC recently ran a series of three live shows, Stargazing LIVE, in which Dara O’Briain and Professor Brian Cox reported on a meteor shower and a partial solar eclipse. The sky may not have always been clear, but the enthusiasm that Professor Cox in particular possesses, certainly was. Along with the main factual content of the show, a few important philosophical points were dropped in:

“I know when I look through a telescope and you see it in real time, so you really see an image of Jupiter, or Saturn or the Andromeda galaxy, for me it’s different to seeing the image on a screen or a picture – there’s something about that connection. I think there’s something in really seeing those things with your own eyes, I think there’s something special about that…”

I understand and agree with what he means. With a small telescope you can see with your own eyes the largest planet in our solar system into which you could fit 1300 Earths, you can see its moons dancing in orbit and you can see its dynamic surface shifting with time.

There is an intimate and unique connection between the cosmos and the observer when heads are tilted back. No one would mention seeing a celebrity photographed in a magazine, but many text messages would be sent after passing someone famous in the street, or seeing them across a room. It makes them real. Photographs, of both celebrities and the night sky, are impersonal and available to everyone. The stars and planets invite you to see them in the flesh, as they really are.

Jupiter with its four large moons, as seen through a small telescope

To gaze upon another celestial body as if it’s just another object on the horizon is to see something greater than you can ever touch. Looking up, really looking up, is the most humbling of pursuits and it is the closest most of us will ever get to the heavens.

But you don’t need a telescope to feel connected…

The sky is a great leveller: it can also be humbling to think that every person you can think of, every king and every peasant, every hero and every villain, in fact, every life form that ever lived (as far as we know) has played out their lives under the same starry setting.

Recognising the constellations in the sky links you directly to everyone between the ancient Babylonians of the 12th Century B.C.E. and the present day. Many would have used the two thousand or so visible points of light to both find out where they are and when they are: Napoleon could point to the North Star just as a flock of migrating ducks can.

Of course you don’t need to know anything about them to enjoy their essential aesthetic, but the enjoyment of looking up is increased dramatically when you know what you’re looking at. Being able to tell your position, your direction, the season and the time just from a simple glance upwards not only saves on owning a Satnav, but it also demonstrates the clockwork precision of the solar system and physical universe.

The planets and stars have moved across the sky in the same way long before humanity rose, long before the Dinosaurs roamed and long before life first stirred from the oceans. We should each introduce ourselves to the neighbourhood: we should start looking up.

Posted in Astronomy, Attitudes | 1 Comment

Insects paint the sunsets

Sunset on the beach, Eastbourne

I was walking along the beach recently and the sun began to set below the horizon. Now, I know this happens every day but I’m not usually outside waiting for it, less likely still to be in such scenic surroundings, so I stopped to watch this mundane daily occurrence to see if it had anything new to offer me. It didn’t. But then, it didn’t have to. Everyone knows the saying ‘Red sky at night, Shepherd’s delight’ but, along with presumably being some sort of simplistic meteorological forecast, the ‘red sky’ delights almost everyone.

As I stood there, shoes slowly filling with sand, I started to wonder: why exactly do the heavens change colour?

After a minute or two of quiet consideration, I hit upon the answer: Insects! Our six-legged friends are the reason for almost all of the delighted shepherds in history…

The story starts, as all good stories do, with a prism…

A prism, doing what prisms do best..

White light from the sun contains many different wavelengths of visible light, which the prism helpfully separates out so that we can see them. Similarly, the atmosphere scatters light from the sun, but air is far better at separating out shorter wavelengths than longer wavelengths: short (blue) wavelengths bounce off air particles on their way to Earth and become visible to us – this is why the sky is blue and, while we’re at it, the Sun appears yellow and not white.

Towards the end of the day however, the sun gets lower in the sky and so owing to the angle that the light hits the earth, it has to pass through a lot more atmosphere. This increased journey scatters almost all of the blue light and the atmosphere acts like a filter, where only the longer wavelengths (reds, oranges and yellows) can get through for us to see.

Sunlight passes through more atmosphere when it is directly overhead than when it is low in the sky...

So, despite the constant and unchanging output of the sun, our eyes receive different wavelengths of light, in different quantities, at different times of the day. But why should I be standing and observing the sky in what are now, frankly, ruined shoes? Why do I see the different colours? Why is the sky red? This is where insects come in…

I perceive the different colours as I possess the ability to distinguish between different wavelengths of light: I have colour vision. It sounds rather simple, but it’s a trait lacking in a lot of other animals within our mammalian kingdom.

It is thought that colour vision was developed and refined as a way of finding sweet, sugary fruit among the green leaves of the canopy – back in the day when we were all just hanging out in the trees. It is, of course, a significant advantage to be able to spot a ripened fruit from a distance without having to rely on stumbling across it. The better the colour vision of the ape, the better chance of finding food.

The plants have their part to play too as they actively advertised the fruit for consumption. The more colourful the fruit (i.e. the more varied the wavelength scattered by the fruit from its surroundings!) the more likely it would be seen by a passing ape and eaten (eventually ‘spreading’ the seeds within far and wide…).

This symbiotic relationship between ape and tree is, however, a delicate one, as it relies entirely on the pollinating insect population: If they didn’t pollinate the trees, there would be no colourful fruit to stimulate the development of colour vision in our anscestors and I wouldn’t be on the beach enjoying the evening sky!

So there it is, the sunset is red because of the tireless efforts of insects and because I like strawberries… what a delight.

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