Explore the COSMOS Observatory on the Isles of Scilly!

In this article I am going to a very special part of the UK, the Isles of Scilly. Back in 2017, when I visited the Isles of Scilly, I thought what an excellent place for astronomy the islands would be. Little did I know at the time that others were also thinking something similar.

The initial idea for the COSMOS observatory, which stands for Community Observatory St Martin's On Scilly, started in 2015 and was borne on the small island of St Martins. One of the islands that make up the Isles of Scilly archipelago.

Mark Holmes, who had set up a community observatory in Cheshire, England. One evening while staying on St Martins with friends, Mark mentioned how dark the night sky is on the Isles of Scilly and that it is unbelievable that there is not an observatory.

Following this comment, this group of friends decided to make the observatory a reality.

To accomplish anything on St Martins, which has about 130 full-time residents, a committee is required. The observatory was set up by a committee made up of about seven members, that is quite a high percentage of the population!

The islands held a series of fundraising exercises after sufficient interest was found on the island. These raised about £25,000. The team behind COSMOS then applied for a substantial grant of about £65,000 from the European Agricultural Fund for Rural Development. In the UK, the astronomy season lasts from September to April, so the observatory could attract tourists outside of the normal tourist season.

It was decided to build the observatory on the field behind the community hall. The first task was to lay a concrete base to stop any vibrations being passed to the telescope. As the observatory is located on a remote island, the transport costs for the concrete were higher than the concrete's cost.

Then in the winter the domes arrived and by the end of 2018 the observatory was ready. Prior to the pandemic in 2019, the observatory was visited by 800 visitors, which indicated the observatory had a bright future.

But why put an observatory on St Martins?

There are some great reasons to have an observatory on St Martins apart from the dark skies, for example, the island has a clear horizon all around, which is helpful since there are often astronomical targets low on the horizon, as most astronomers know. The other is that the stars do not twinkle, or when they do they twinkle a lot less on the Isles of Scilly. Due to being in the middle of the sea, a large land mass does not cool down at night, releasing hot air into the sky that makes the air shimmer. This gives you get a much better view of the night sky.

The Isles of Scilly have the darkest skies in England even darker than the night skies on Dartmoor. Although the island council is forward-looking and has limited what lights can be used on the islands, it isn't a dark sky reserve. Due to the island council's small size, they have not been able to deal with the bureaucracy to get the dark sky reserve status confirmed.

The observatory consists of two domes and three main telescopes: an Altair Wave Series 130mm F7 ED Triplet APO Refractor Telescope with a Coronado Solarmax III 70 BF 15 Hydrogen Alpha Solar Telescope piggyback mounted on top in the first dome. The Solar Telescope is available for visitors to look through during the day.

And in the other dome there is a large 14" Schmidt Cassegrain Telescope. Since this is a community observatory, the amateur astronomers at the observatory are learning their equipment as they go.

The observatory itself is well worth the visit. On maps online, it was not clearly marked, but it can be found at the back of the Community centre in Middle Town.

Potential visitors should also be aware that the transport links between the other islands, especially the main island, St Marys, which most people stay on, are very limited after dark. So, you should stay on St Martins itself if you intend to visit the observatory at night. To get back to the island of St Marys, I had to take a speed boat at 9:30 pm, which was the latest they could get me back. The journey from the island to the lower quay involved walking through dark lanes and then a fast ride back on speed boat! To see the observatory for yourself please watch the episode below:

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