Give Your Loved One a Real "fallen Star".

Several times every year, the sky falls in.

Well, bits of it do - regular and predictable meteor showers happen all round the world, leaving burning trails across the sky as friction burns them away to nothing.

Or does it?

It may be romantic to name an anonymous dot in the sky after your loved one, but how about catching a real "fallen star" for them?

I'm sure you've realised that, when I say "fallen star", I really mean "meteorite". You hadn't? Well, you do now.

To catch the meteorites, you will need:

• Magnets in a plastic bag
• String

To view the meteorites, you will need:

• A pair of non-magnetic forceps or tweezers - it is possible to manage with nimble fingers, but you are more likely to lose any interesting samples.
• A microscope slide, preferably with a concave depression to stop things rolling away.
• Clear nail varnish or "super" glue (CA glue, crazy glue)
• A narrow-nibbed permanent marker.
• A microscope.

First, you need a meteor shower. There are several showers every year, and numerous online calenders such as this simple one or this more detailed one to allow you to plan your fishing trip. Another useful site is http://www.spaceweather.com , which also has details of comets that could give rise to new showers.

To make things even more romantic, you could choose a shower that falls on or near a significant date, such as the date you met, your loved-one's birthday or the date you intend to marry.

(As I type, the Quadrantid shower has just passed its peak.)

You then need rain.

When a meteor enters our atmosphere, it is travelling at anything up to 71,000 ms^-1 (about Mach 10, speeds otherwise known as really, really fast). Friction with the atmosphere brightly burns the meteor away to almost nothing. What remains is meteoric dust.

This dust can hang around in the atmosphere for days, or even months, unless it encounters a cloud. At that point, the dust particles act as nucleation particles - they provide a point for water vapour to condense and form a rain-drop.

So, in the days during and shortly after meteor showers, you need to keep an eye out for puddles that have collected plenty of water, but preferably away from streets and car-parks (where the puddles will be heavily contaminated with particles of rust).

Put your magnets in your bag and tie the neck shut with one end of the string.

Hold the other end of the string and drag the bag back and forth through the puddle, stirring up the silt.

If you don't want to wait for rain, you can always go fishing for "real".

All you need to do is find a body of water that has been collecting rainwater without moving very much. They should also be in a location where rust and rubbish are unlikely to have been dumped in the water - a garden pond is ideal.

The only problem is that you will not know when the micrometeorites fell.

• If you want to put a bit more effort into your collection, you could fish about in your gutters for magnetic particles (months or years of rain will have left them there), or set up a rain-barrel to be fed directly from a large roof and allow you to fish about in the barrel whenever you wish (perhaps collecting weekly samples to provide a glimpse of the annual cycle of meteor showers hitting this world we call Home).

When you are fed up with fishing, turn the bag inside out as you peel it off the magnets (trapping any meteorites inside) and take it to your shed laboratory. If your fishing hole is some distance from home, you will find it easier to put the bag of magnets into another bag to carry it back, then deal with it there.

_{(A small warning - don't put the pot full of magnets in a pocket near your wallet. Magnets do unpleasantly permanent things to credit cards.)}

Back at the shed laboratory, lift the bag back out of the pot and use the forceps to pluck particles from inside the inside-out bag (remember - you turned the bag inside out) and place them on the microscope slide.

You could use your fingers, but the particles are more likely to stay stuck to your fingers and be lost.

Place the slide under the microscope and look.

• Start with the stage lowered and the smallest objective lens selected.
• Raise the stage slowly to bring the particles into focus.
• Gently manoeuvre the slide to bring any likely-looking candidates into the middle of the viewing area before increasing the magnification.
• If you need to move particles around on the slide, do not use a normal needle or pin - time spent stuck to the magnets will have magnetised the particles so that they stick to the needle, and needles are often naturally magnetised as well. Use a splinter of wood or a brush-bristle to move things.

Identifying micrometeorites.

You have done the first step, selecting iron particles with your magnet.

Next, you are looking for signs of melting - your particle should look like a frozen black or grey droplet, probably with a pitted surface. You may be lucky and get an almost spherical drop.

If the particle is reddish-brown and flaky-looking, or with lots of spiky corners, you have probably just found a speck of rust.

Unfortunately, I have not been able to take decent photos of the micrometeorites I found through my microscope lens, so here are a few micrometeorite images from the Net:

http://www.comune.pisa.it/apsn/Minerali/meteo.htm

My pig-latin translations of the captions are:

"Micrometeorite non sferica" = non-spherical micrometeorite
"Micrometeoriti magnetizzate" = magnetic micrometeorite
"Micrometeoriti ferrosa e vetrosa" = iron and glassy micrometeorites
"Micrometeorite cava" = micrometeorite with a dent.

Now that you have found your micrometeorites, you need to preserve them so that you can give them as a gift.

The first thing to do is to leave the slide alone. You want the micrometeorites to dry out, but if you use any sort of blowing to dry them, you run the very real risk of them blowing away.

Stand the slide somewhere warm, horizontal and draught-free. On a radiator is good, or on a clear shelf in an airing cupboard. If you're in a rush, hold the slide by one corner and rest it a-top a lit tungsten bulb.

When the slide is dry, the micrometeorites need fixing and protecting from water. There are "proper" preservative agents you can buy from specialist suppliers, but two very suitable alternatives are "super" glue or clear nail-varnish. I would probably recommend the glue, as it is less likely to trap bubbles of air.

Being very careful, add a drop of glue (if your varnish is in a container that won't drip, use a needle or pin, dipped into the varnish to pick up a single drop of varnish) to each of the micrometeorites you have identified, and leave it to dry.

When it is dry, use the permanent marker to label the slide with the details of what it is, and why it is significant - Fallen stars gathered from the birthsign of my darling.

• To present your slide, use photo album corners to fix it inside an appropriate card, or online scientific stores and certain auction sites sell card packs that will hold a single slide. If you want to make more of a fuss of the gift, you can cut a rectangular hole in a piece of mounting board and present the slide framed - your loved one will then be able to hang your gift on the wall, even if they can't view them properly with a microscope.