Hear how gravitational waves tell us of events far across the universe – and then get into the pool and enjoy music and sound art which can be heard both above the water surface and below. With audiovisual artists Leon Trimble and Joel Cahen and gravitational waves researcher Dr Andrew Spencer from Glasgow University.

The dust from Mount Hekla’s eruption in Iceland in 1845 helped Orkney potatoes' flavour. Could rock dust do the same for tomatoes? Growers in Orkney and Moray have grown and harvested a selection of tomatoes for you to taste, some fertilised with rock dust and some without. Hospitality students at UHI Orkney will prepare and serve them for you to assess.

Take the 6 pm ferry from Stromness for an islands evening in nautical mood. Lorna Summers describes Portsoy on the Moray coast, its past herring days and today's Traditional Boat Festival. Dr Vassilios Spathopoulos tells of the 2,000-year-old Antikythera mechanism, found in an ancient shipwreck, which used bronze gears to predict the position of sun, moon and planets.

Clear and concise insights from two speakers from the University of Central Lancashire, with time for refreshments in between. Charlotte Proverbs describes the physics of the solar wind that sweeps outwards to encounter the Earth’s magnetic field and form the Northern Lights. Dr Catherine Tennick will explain some of the physics of forensics, from fingerprints to fibres.

This is a special event linking the frontiers of astrophysics with the frontiers of music – in the context of Orkney’s deep past. There will be new music and the story of its creation through the inspiration of gravitational waves, and something about their background as well. And there will be news of plans for a project for next year for which this is the first step.

Come along to help a group of mathematicians to realise a vision! They want to show in a highly visual way one of the fundamental structures in the world of numbers – the nature of prime numbers. They are going to use cardboard boxes to build up blocks and towers of numbers, like buildings in a city – and they need you to help them!

Come along with friends and family to see the equipment and the people who operate it. The depot has a map of Orkney’s electricity network, plus activities and careers information. Everyone welcome.

Ancient middens provide vital clues to archaeologists about the people who left the material behind. You can see the process of deduction by looking through – (clean!) – modern rubbish, and noting clues it provides to the people who dumped it. Call in and try your own powers of deduction, and learn about the importance of middens, and how to think like an archaeologist.

It’s a great sight on Broad Street in front of the Cathedral, with an opportunity to see cars that can range in time from early days to a new electric vehicle of today – and with over a hundred years of vintage vehicles, classic cars and tractors in between, along with the sound of engines in action, and all beautifully restored.

Kirkwall City Pipe Band with their final parade of the season.

Conducted by Rev. June Freeth, with the St Magnus Cathedral Choir. “Whether you come from north or south, east or west, whether you live here or are a visitor, are here for the first time, or are here regularly… you are welcome to our worship,” they say.

Come and see and hear about the science behind Orkney’s health service. You can also find out about the systems which have made the building Europe’s first net-zero hospital, and visit the outdoor polytunnels. Across the road there is the opportunity to see and hear more about the development of Arcadia Park.

It's 100 years since Kirkwall Town Council's initiative to bring mains power to the town. Later came the establishment of the North of Scotland Hydro-Electric Board which built the power station of today and gradually extended the electric network around the islands. The achievements of 100 years are marked by the unveiling of a plaque funded by SSE Transmission. Everyone is warmly welcome.

with the Craig Mainland Dance Band, for would-be and why-not dancers of all ages. Supper is included in the ticket.