100 Hours of Astronomy

100 hours banner

Make friends with the sky

Thursday 10 to Sunday 13 January 2019

All around the world, people will be gazing at the sky during this period of (just under) 100 hours. It’s been set up to celebrate the centenary of the International Astronomical Union, which organises the world’s astronomy community. So we want as many people as possible to look up at the sky, do some Moongazing, find a few celestial bodies and maybe learn a constellation or two. We’ve got some great projects for everyone.

All you need to take part are clear skies, some warm clothing and enthusiasm! Doesn’t matter where you live, whether in a city or in the wilds of the countryside, you can still see something and have some fun. You don’t need a telescope, but if you have binoculars, or can borrow some, it will help.

Here’s what you can do:


We all know that the Moon is up there in the sky, but have you ever really looked at it?  See how its appearance changes, and spot the place where the Apollo astronauts landed 50 years ago! Have fun with our projects to draw it or photograph it. No matter how light-polluted your sky, the Moon is an amazing sight. And learn more with our Ten Things You Didn’t Know About the Moon.

Phases of the Moon
The phases of the Moon during the 100 Hours of Astronomy from 10 January (left) to 13 January 2019, as seen from the UK. Credit NASA’s Scientific Visualization Studio/SPA

Find Orion

Orion is the brightest constellation and the easiest to spot, even from city skies . Find Orion and pick out the Orion Nebula, birthplace of stars.

Get acquainted with the Seven Sisters

You can see this brilliant star cluster from anywhere. Count the stars and test your eyesight.

Spot Mars

The Red Planet is well placed in the evening sky. See it for yourself and find out more about our exciting neighbour in space.

Observing events

There are observing events being organised in the UK during the 100 Hours. To see if there is one near you, go to:


The official hashtags for this international event are #IAU100 and #100hoursofastronomy.

The Society for Popular Astronomy is a community of people who enjoy watching the night sky. We welcome beginners to stargazing, and our aim is to make astronomy fun! Why not join us? You can find full details of how to become a member here.