Hunting for space dust
The question
Can we find tiny magnetic spheres in rainwater or roof dust, and how can we tell whether any might be from space?
Thousands of tonnes of space dust land on Earth every year. Scientists have found micrometeorites in dust from city roofs, but most magnetic specks in towns are made by people, so careful checking is part of the science.
Equipment
- A clean bucket or large tub left outside to collect rain, or dust from the bottom of a downpipe collected by an adult
- A strong magnet inside a plastic food bag
- A sieve or tea strainer, white paper and a saucer
- A strong hand lens, or better, a microscope with 20 to 40 times magnification
Method
- Leave the bucket open in a clear spot for a week, then pour away most of the water slowly, keeping the sludge at the bottom.
- Let the sludge dry on a saucer.
- Move the bagged magnet over the dry dust, then hold it over white paper and pull the magnet out of the bag so the particles drop off.
- Sieve out large bits and look at what is left under the microscope. Look for tiny round balls.
- What to measure
- How many round magnetic balls you find, how big they are compared with a millimetre scale, and what their surfaces look like.
- How to present it
- Microscope photos or drawings, a description of each method, and an honest discussion of why your spheres are probably made by people, and what an expert would check to know for sure.
- Take it further
- Compare dust from a busy road with dust from a quiet garden. Which has more magnetic particles? What might that tell you about where they came from?
Safety
Never climb onto roofs or ladders: an adult collects any dust from ground level. Keep magnets in the bag, wear gloves when handling dust and sludge, and wash hands.