A bright Perseid photographed over the VLT telescopes. Despite the clear skies, even here observers would not have seen a zenithal hourly rate. Image credit: ESO/S. Guisard

Aug 16, 2015 Perseids brought us another shower . . of media hype

Sen—This week saw one of the strongest meteor showers of the year reach its peak. After a slow build-up since late July, the Perseids delivered maximum rates on the night of August 12-13 as comet dust poured from space into the Earth’s atmosphere.

It was an exciting time to be an amateur astronomer, albeit at the mercy of the weather, and I took the opportunity to watch for the “shooting stars”, taking hundreds of shots with my camera in an attempt to capture some trails too.

Meteor showers have fascinated me since I was a teenager, and I recall sitting out then in the school summer holidays, when my parents’ garden could still enjoy dark skies, with a plainly visible Milky Way demonstrating the lack of light pollution. I took it more seriously in those days, and watched with friends for several hours, with every meteor duly logged in a notebook with full details of its brightness, speed, colour and so on.

Back in those days, nearly 50 years ago, much of the industrialised world still managed to have dark skies within reach, but such natural astronomical events failed to make the pages of the newspapers, or be mentioned on radio and TV news. I had a sense that space news of any sort was rarely reported unless it came from American media first. Nowadays—and I may have helped make this happen in my many years in national news journalism in the UK—heavenly phenomena are far more likely to be reported. Even the weather forecaster is likely to start chatting about your prospects for observing those summer meteors, which is great, isn’t it? Well . . .

My worry is that such events are becoming very overblown, with the phenomena built up so much by the media that the actuality of the event can only come as a disappointment to most people who then try to see it for themselves. I heard the venerable old BBC say the meteor shower would be “dazzling” on the radio, TV and online. And many invited commentators allowed themselves to be carried away on the wave of enthusiasm being generated. You might have expected a lighting up of the skies to rival the most spectacular firework display ever mounted, if not special effects from Star Wars.

I spoke to a number of friends and acquaintances who saw the build-up and decided to watch for this dazzling display and then found it did not quite meet those dizzy expectations. Granted they probably did not sit, staying focused on the sky, for very long, but most saw two or three at best. Dedicated amateurs who reported back had mixed fortunes, and early analysis suggests rates may have been better over the USA than earlier over Europe. But nowhere was this shower exactly falling like raindrops.

The first clue that this Perseid shower was not going to rival the municipal firework display should have come when the various commentators predicted that people watching under a dark sky might see a hundred or so meteors an hour. But even this figure is misleading because it gives a very false expectation of what will occur.

As it happens, the Perseids did indeed peak at around 100 meteors an hour according to the first reports from the International Meteor Organization. But that is a figure termed the Zenithal Hourly Rate (ZHR) and is a hypothetical sum derived from observations actually made, and always much higher than people actually saw. The ZHR is calculated as what the visible rate would be for a single observer if the radiant from which the meteors appear was in the zenith, and skies were perfectly dark and clear of cloud. Those are circumstances that I, for one, have certainly never enjoyed, but possibly someone nearer the equator, and in the middle of an arid desert might get now and again if they were lucky. The rest of us have to make do with less than ideal sky conditions, some stray lighting from nearby cities or towns, and a radiant that is much closer to the horizon. All these factors cut the rate of meteors seen dramatically.

So does it matter? Surely it is great to get the word out to the general public about natural phenomena such as the Perseids. It helps promote astronomy and an interest in the world and Universe around us. Well my worry is that if we over-hype such events, then the non-astronomers who decide to see for themselves can only end up disappointed. And if it happens again and again, our astro-evangelists end up looking more like the boy who cried wolf!

I have seen some very impressive meteor displays, notably the Perseids in 1983 when their parent comet was close by, and the Leonids which produced a night of fireballs in 1998 and then brief storms around the turn of the century. But generally, across the years, I have been perfectly content with the lower rates of meteors that have been delivered, furnished as I was with more realistic expectations.

It must be good to see more awareness of astronomy among the general population, even when some of it seems to be a fuss about nothing, such as with the frenzy of interest in the “supermoon” and July's “blue moon” for example. I was happy to go on national radio to be interviewed about last year’s morning conjunction between Venus and Jupiter because it was a genuine spectacle, albeit just a chance alignment.

But we should guard against too much hype—and that surely goes for the professional astronomer too. Galaxy collisions are sometimes described as if they were disaster movies. Press releases attempt to outdo each other in telling us about newly discovered exoplanets, for example, even down to the clouds in their skies and the colour of any trees! In reality, a lot of imagination is employed in creating pictures of worlds from tiny signatures in the faintest of light. Twin Earths are announced when one cannot even be certain that the newly found world is rocky. Yes, all this brings a flurry of interest in the science and the teams behind it. But shouldn’t we be careful to keep some sort of grip on reality?