Transit of Mercury


Dear Members,

From 12 noon until 8 p.m. on Monday, 9th May the Society's observatory in Dyffryn Gardens (at St Nicholas, Vale of Glamorgan, CF5 6SU) will be open in order to allow Society members to observe the transit of Mercury from east to west across the face of the Sun. Members - who must produce their Society membership cards - will be permitted to go direct to the observatory via the right-hand gate but will not be allowed to wander the gardens unless they pay (or show their NT membership card) and enter through the Dyffryn Gardens visitors' centre. Successful viewing of the transit will of course depend on the skies being clear on the day.

The transit - or passage - of a planet across the face of the Sun is a relatively rare occurrence, and Mercury's transit on the 9th of May will be its first since November 2006 but that event was not visible in the UK.

Officers from the Society will be on hand to show members how to view the transit in a safe manner using the Society's telescopes which will be fitted with appropriate protective filters. Members can also bring their own telescopes, if they wish, but they should take care to avoid looking directly at the Sun or viewing it through telescopes unless these are manufactured for that purpose or equipped with eyepieces and filters that are manufactured for that purpose. They must have been checked to ensure they are not defective in any way. Failure to use protective measures can result in significant eye damage and even lead to blindness.
We encourage members to arrive at the Observatory from about noon but before 7 p.m. at the latest.

The Dyffryn Gardens website is at

Please note that all private equipment brought to CAS events is not insured by CAS and therefore CAS shall not be held liable for any damage or loss. The owner of the instrument is responsible for the safe and proper use at all times in accordance with manufacturer's instructions.

In Association with