How to observe meteors – Part One
Observing meteors can be one of the most instantly rewarding ways to enjoy astronomy, so here is some advice on how to view them. If you are lucky, and a little patient, you may be treated to a fine natural display of nature’s fireworks.
A bright Perseid meteor
Meteors – commonly known as shooting stars or falling stars – are, of course, not stars at all. They are the streak of light that appears when a piece of celestial debris enters the Earth’s atmosphere and is destroyed.
But what appears as a bright flash high above is usually no bigger than a grain of sand. The much rarer, larger chunks blaze more brilliantly and can produce so-called fireballs that rival Venus and sometimes even the Moon in brightness.
Meteors can appear at random at any time. Those who spent long spells out under the stars will have spotted them quite frequently. Meteors are fragments of material ejected by comets orbiting in the solar system. At various times in the year, the Earth’s orbit crosses the rivers of dust left by different comets and around those times we see what are termed meteor showers.
Meteors that cannot be linked to a shower are called sporadics. They can be told apart from members of a shower because the shower meteors will appear to radiate from a particular point in the sky. No matter in which part of the sky you see the meteor, you can trace back its path and it will cross that point. The meteors appear to have shorter paths the closer they appear to the radiant because they are heading more directly towards you.
The effect is one of perspective. The meteors are actually flying parallel to each other as they stream into the atmosphere but traced back, their paths converge on their radiant just as the parallel lanes of a long straight motorway appear to converge in the distance.
Meteors can appear anywhere in the sky but shower members can be traced back to a radiant, in this case that for the Perseids
Different showers are usually named after the constellation in which the radiant appears to lie. So a strong shower that occurs every August and appears to radiate from the direction of Perseus is called the Perseid meteor shower, or simply the Perseids. Similarly a major December shower radiating from Gemini is known as the Geminids. Some shower names even specify a bright star close to their radiants such as the Delta Aquarids or Kappa Cygnids.
The word shower may lead one to expect rather too much. Unlike a shower of raindrops, even the finest meteor shower will normally produce no more than one or two meteors a minute at best for an observer. There have been exceptional occasions when a so-called storm occurs and they can appear to be raining out of the sky, but they really are very rare. They happen when the Earth passes through a dense clump of particles in the stream’s orbit. (For example, the Leonids generally reveal just a handful of meteors at maximum in November but many thousands an hour may be seen at intervals of around 33 years).
Even so, at various times in the year when the Earth meets one of the regular reliable showers, it can be very rewarding to sit outside and watch the show. You will need to be patient. Don’t expect just to glance upwards and see a meteor straight away. Instead prepare yourself for a watch of several minutes at least for the best chance of some results. For more on meteors and how to observe them see How to observe meteors – Part Two.
