Can aluminum pie plates catch on fire outside in the sun?

It's unlikely for an aluminum pie plate to catch on fire outside in the sun. Here's why:

* Aluminum's Properties: Aluminum is a good conductor of heat, but it has a relatively high melting point (around 1220°F or 660°C). The sun's heat is unlikely to reach that temperature.

* Sunlight Intensity: While the sun can be intense, it's not enough to directly ignite aluminum. The energy would be spread over the entire surface, making it difficult to reach the ignition point.

* Reflectivity: Aluminum is also reflective, meaning it will reflect some of the sunlight, further reducing the amount of heat absorbed.

However, there are a few things to consider:

* Darker Colors: If the pie plate is coated in a dark color, it could absorb more heat. While unlikely to cause a fire, it could become hot enough to burn if touched.

* Focussing Effects: If something like a magnifying glass were to focus sunlight onto a small area of the pie plate, it could potentially reach a high enough temperature to melt or cause damage.

In conclusion: It's highly unlikely for an aluminum pie plate to catch fire in direct sunlight. However, it's best to be aware of the possibility of it getting hot and taking precautions if necessary.