Seven things everyone wants to know about the Universe

As 2009 comes to a close, so does our very own celebration of the International Year of Astronomy 2009. With kind support from the Royal Astronomical Society, we've been running a project giving you the chance to nominate those burning questions about the nature of our Universe. In online polls dotted throughout the year you told us what you wanted to know and we put the questions to world-leading experts. With the final question being answered in this issue of Plus, we can now give you all the seven articles on the questions you nominated. Be prepared for having your head spun!

• What happened before the Big Bang? by John D. Barrow, accompanied by a podcast
• Are the constants of nature really constant? by John D. Barrow, accompanied by a podcast
• What is dark matter? by Sir Martin Rees
• What is dark energy? by John D. Barrow
• How does gravity work? by Bangalore Sathyaprakash, accompanied by a podcast
• Is time travel allowed? by Kip Thorne
• How long is a day? by Nicholas Mee.

Happy reading!