Meteor Echoes - March 26th Print E-mail
At our March meeting Allan Bell gave us a talk about Meteor Echoes, in which he explained how radio (and radar) could be used to watch for meteors, and how meteor trails could be put to other uses. Meteors produce trails of ionised gas which may persist for several minutes, and these will reflect radio signals if the geometry is good. Ideally, a powerful VHF transmitter needs to be located outside line-of-sight reception distance, so that the receiving station will only receive a signal when a meteor trail is in a suitable location. In the past a transmitter in Gdansk transmitting on 70MHz served well, but while it is still used at times, it no longer transmits all night. A VHF beacon GB3ANG transmits continuously from Scotland, which satisfies the over-the-horizon requirement for observers in the South of England, but it only emits ten watts, so a large antenna is needed if it is to be used for meteor observations. In the USA meteor observers have used VHF TV and NASA satellite radar system signals for meteor observations. Even if the geometry is good, not all signals come via reflection from meteor trails. Atmospheric and Ionospheric conditions can also give over-the-horizon reception of VHF signals, and if a transmitter is strong enough then reflections off satellites can also be heard. Allan rounded off his talk by explaining that meteor echoes can be used for more than simply counting meteors. They can also be used to hold short over-the-horizon conversations on VHR radio, and there are a number of scientific stations using dedicated transmitters and arrays of receivers to determine the atmospheric conditions at meteor altitude much more economically than by using sounding rockets.
 
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Members Evening TalkPeople interested in joining the society are welcome to attend a couple of meetings as guests.

Some of our meetings are given by well known astronomical personalities, and others are home grown and ideally suited for absolute beginners.

The reports of past meetings gives a few examples. Throughout the year we make sure topics, both new and old, are covered and give particular attention to local newsworthy items.

There's plenty of advice especially if you're buying that all important first telescope!
 
Ordinary Meetings at High Elms

Our regular monthly meetings are held at Bromley Environmental Education Centre at High Elms (BEECHE ) on Shire Lane. Car-parking at the Nature Centre itself is restricted to those with mobility difficulties and those bringing equipment. Most members should park in the main High-Elms car-park as shown on the map. This car park will remain open until after our meeting.

Map showing location of High Elms

 

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If you would like a specific subject to be covered at one of our monthly meetings why not send us an email. We do our best to get interesting and up-to-date talks organised, but sometimes our newer or younger members would like to know something about the sky that we have not yet covered. Perhaps teachers may like a senior member of our society to give a talk about astronomy to their school, we would be most pleased, just send an This e-mail address is being protected from spam bots, you need JavaScript enabled to view it