Â鶹´«Ã½

If an Earth-sized rogue planet passed through our solar system, missing the planets, how much disruption would it cause?

David McKenzie,

Launceston, Tasmania

Would it be possible for an intelligent species to develop an advanced technological civilisation without the wheel?

Joe Roberts,

St Austell, Cornwall, UK

To answer this question – or ask a new one – email lastword@newscientist.com.

Questions should be scientific enquiries about everyday phenomena, and both questions and answers should be concise. We reserve the right to edit items for clarity and style. Please include a postal address, daytime telephone number and email address.

Â鶹´«Ã½…