The Royal Observatory, Greenwich is the home of Greenwich Mean Time and the Prime Meridian of the World, making it the official starting point for each new day and year. It is also home to London's only planetarium, the Harrison timekeepers and the UK's largest refracting telescope. It runs the annual Astronomy Photographer of the Year competition.

Radmila Topalovic is an urban astronomer and physics teacher based in South-East London, and Astronomer Emeritus of the Royal Observatory Greenwich. She holds a degree in Physics with Astrophysics and a PhD in Astrochemistry. Her biggest passions are quantum physics and astrobiology.

Tom Kerss F.R.A.S. is an astronomer and the author of numerous best selling books about the night sky for both adults and children. Having worked at the Royal Observatory in Greenwich for more than six years, he now shares his passion for the stars with people all over the world, delivering courses, podcasts and media interviews. Tom loves nothing more than to seek out the darkest and most beautiful skies on Earth, but he does most of his stargazing from his home in London. Find out more about Tom's projects at tomkerss.co.uk

Collins Astronomy is the home of the bestselling annual Guides to the Night Sky, Night Sky Almanac and also publishes the Astronomy Photographer of the Year collection and other popular astronomy books.