A Perseid meteor is captured passing over the VLT telescopes at Paranal, Chile. Image credit: ESO/S. Guisard

Sep 6, 2015 A vacation taking in meteors . . . and a trip to Mars

Sen—I hope many of you were able to catch some of August’s famous natural firework display, the Perseid meteor shower. Following a peak on Aug. 13, rates dropped sharply but I saw a couple of likely shower members ten days later when I was taking my image of Comet 67P/Churyumov-Gerasimenko.

It was all over before the end of the month, but I still had “shooting stars” on my mind as I headed to Austria on Aug. 25 for the International Meteor Conference, which has become an annual must-visit for me in recent years. I try to combine it with a holiday, and this year I was able to combine the event with a few days in Vienna—and a visit to Mars, as you will see later!

The gathering is organised by the International Meteor Organization (IMO), an amateur-led group based in Europe but with members worldwide. And the conference, like IMO’s other activities, is very much a professional-amateur, or pro-am, affair with very high scientific standards, and performing cutting-edge work in meteor research. The many amateur observers are supported by a number of members who carry out science for a living, and regular attenders at the conferences include professionals from universities, observatories and the European Space Agency.

This year’s conference was held at Mistelbach, a small town to the north of Vienna. More than 125 people attended from 27 different nations, including faraway countries such as the USA, Japan, Russia, South Korea and Taiwan.

Once again, it was enthralling to hear of the work of this dedicated band of enthusiasts. I’ve mentioned before that when I was a teenager, back in the 1960s, meteor observing was a favourite activity of mine. In those days, we just sat out in a deckchair or sunlounger, staring at the heavens and waiting for meteors to appear. We diligently noted each one seen, with such details as their brightness, or magnitude, colour, speed and position in the sky, along with a decision as to whether the object was part of a known shower or a random intruder, known as a sporadic.

One flaw in this approach for a single observer was that you might spend so long writing down details for one meteor that you were likely to miss one or more others, reducing the effectiveness and accuracy of the count, which was designed to help meteor scientists learn more about dust particles, or meteoroids, in the Solar System that produced the bright streaks as they entered the Earth’s atmosphere. So we were encouraged to observe in small groups, allowing us to monitor the whole sky and to allocate the job of noting the meteor details down to one person at a time.

Technology also came to our aid, with the earliest Philips cassette recorders appearing on the market. I remember a member of my local society bringing one along to a Perseid watch on a disused airfield, but using it to play music. I was so mesmerised by the sounds of Pink Floyd’s Ummagumma, made even more psychedelic by the wavering battery level, that I rushed out to buy the album next day and there was instilled a life-long devotion to the group’s work.

In those days, you could also try to capture a few meteors with your camera, but even with high-speed film, it was a chancy business. You could run several expensive reels through the camera, then not know whether you had recorded anything until you had later had the film developed. Only the very brightest would be caught, and you would curse those magnificent meteors you’d spotted which passed just outside the camera’s field of view.

How different things are today. Computing power plus sensitive electronic cameras have allowed enthusiasts to record and study meteors as never before. CCD cameras designed for astronomy, as well as adapted security cameras, are allowing large regions of the sky to be monitored throughout the night, with quite faint meteors registering on the images they take. There are now networks of these cameras around the world, and when the same meteor is caught by multiple cameras in one region, the combined data allows the orbit of that particle, or meteoroid, through the Solar System to be determined.

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A chunk of Mars in the form on a Nakhla meteorite in Vienna's Natural History Museum. Image credit: Paul Sutherland

Collecting data in this way from many thousands of meteors allows professional astronomers to map out with increasing accuracy the streams of dust particles left by comets as they orbit the Sun. Other amateur astronomers are attaching spectroscopes to their cameras and so discovering the different elements that make up each meteor’s dust, or using simple radio telescopes to detect daytime meteors that would otherwise be invisible.

I don’t think I have ever seen such a hard-working and devoted organization, where so many of its members are actively contributing to a field of research. And the results they are achieving are a vital area of research to stand alongside the ongoing efforts of space scientists to study comets and other small bodies in the Solar System. For while the European Space Agency’s Rosetta space probe observes Comet 67P/Churyumov-Gerasimenko up close, witnessing the emission of jets of dust from its nucleus, the IMO’s enthusiasts are helping reveal what happens to such dust as it spreads around a comet’s orbit, and until some collides with our atmosphere and is destroyed. Between Rosetta and these ground observers, we are seeing the birth and death of a meteoroid.

Oh yes, that visit to Mars. Well it wasn’t all talks and presentations at the conference. Social activities included an excellent evening at a local winery where local wines were tasted and fine Austrian cooking enjoyed. And on the Saturday afternoon, we spent a fascinating afternoon touring the extensive meteorite collection at Vienna’s Natural History Museum. (Meteorites differ from meteors in that they are objects that have reached the ground, and they are usually fragments from the asteroid belt rather than products of comets.) Vienna has one of the world’s finest collections of these cosmic rocks, among them a number that have been identified as being from the Red Planet.

It is always a thrill to see these rare and precious objects, ejected from the martian surface by asteroid impacts many millions of years ago and spending aeons circling the Sun before a chance collision with Earth. I’ve seen examples before in museums in London and Berlin, but to visit Mars once more was, yet again, an out-of-this-world experience.

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