91É«ÇéƬ

Is there a correct way to fill a dishwasher to maximise capacity and cleanliness?

Conor McKeating,

Dublin, Ireland

Will there ever be a time when all the planets of our solar system line up in a row, one behind the other, as seen from Earth?

Sue McLennan,

Parkes, New South Wales, Australia

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.

91É«ÇéƬ retains total editorial control over the published content and reserves all rights to reuse question and answer material that has been submitted by readers in any medium or in any format.

Terms and conditions apply.