I am thinking of planning a holdiay to see the Aurora Borealis as a surprise for my husband. We like to travel independently and by rail. When and where are the best times and places to go and is it feasible to cross to Scandinavia by ferry and then to catch a train? Anon, by email

Times Online rail expert Alan Heywood responds: The Aurora Borealis or Northern Lights typically appear as light green "curtains" floating across the night sky but may also come in other colours or even plain "white". They are caused when electrically charged particles in the magnetosphere collide with atoms and molecules from the upper atmosphere.

Certain conditions must be met before the Aurora is visible and most of these are rather obvious when you think about it!

Firstly it must be dark - the darker the better so this means no light pollution from big cities and little or no moon. Secondly the sky must be totally clear of any cloud. Thirdly it must be winter (certainly no earlier or later than the Autumn and Spring Equinoxes respectively). Fourthly the time should be around midnight (I don't know why, especially when, in the far north in winter, it is dark for most of the day). Finally, the further north you go, the better. Preferably you need to go further north than the Arctic Circle as, whilst sightings are occasionally reported in Southern Scandinavia and even Scotland, these are rare.

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So there is a huge element of chance in your quest to give your husband a surprise and, just to give you an indication of this, I've only seen the Aurora twice in my travels. A long time ago I did two round trips with the Norwegian Coastal Steamer (Hurtigruten), both in December. On just one occasion during the whole of this time I saw a very poor display for about five minutes in the Tromso area. The second viewing was much better but that was from the port side on a flight from Vancouver to Heathrow which took us over the polar route in late January.

Now, let's take a look at the railway options. Unfortunately, the railway routes in Scandinavia don't really go far enough north for your purpose. There is a very scenic line northwards from Trondheim to Bodø in Norway which crosses the Arctic Circle although Bodø itself is ony some sixty miles north of the Circle. Do bear in mind that at the time of the year you need, much of the scenery would be lost to you. In December and January Bodø only gets about five hours of daylight and it would be dark by mid afternoon - long before your train reaches its destination.

The other line goes north from Stockholm in Sweden, then crosses Lapland and finishes on the Norwegian Coast at Narvik.

Of the two, the first is much better for scenery although the second does give the opportunity to visit the lovely city of Stockholm as part of the holiday.

In both cases, you would have quite a long cross country trek if you wanted to do the whole journey by rail. Leaving London by Eurostar to Brussels, you would then go across Germany to Hamburg, then into Denmark to visit Copenhagen before crossing into Sweden. Here the routes diverge. The Bodø jouney would take you north to Oslo, then north again to Trondheim. The Narvik route as I comment above goes via Stockholm.

It would be possible to avoid overnight trains on the Bodø route by having overnight stopovers in Cologne, Copenhagen, Oslo and Trondheim. On the Narvik route, the only train between Stockholm and Narvik involves an overnight journey - there are, of course, sleeping cars available.

An alternative to the long overland journey would be to fly to Oslo or Stockholm.

As I mentioned above, I don't feel that any of these options will give you more than a passing chance of seeing the Aurora Borealis and I wonder whether taking the Norwegian Coastal cruise would be more appealing. This is a twelve day cruise from Bergen with departures daily. Although you would have cruise comfort and facilities, the route is a regular passenger and freight service to the remoter parts of the Norwegian coast and you would get to see a lot of local interest. When you call at the various ports en route you can go ashore for a while and, for your purpose, it is possible to go out on deck late at night well away from centres of population - to be on deck at midnight as the ship passes through the narrow Raftsund Channel in the Lofoten Islands is quite an experience. Have a look at www.norwegiancoastalcruises.com

You can combine this with a stunning railway journey by arriving at Bergen from Oslo on the wonderful Bergen Railway - part of the Norwegian State Railways network. Visit them at www.nsb.no for timetable and fares information.

Of course, you don't need to confine yourself to Europe - there's a lovely railway from Anchorage to Fairbanks in Alaska but that, perhaps, is another story.

Alan Heywood is a director at rail specialists, Ffestiniog Travel

Got a question for Alan? Email us at yoursay@timesonline.co.uk

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