The Penllergare Observatory is a Grade II listed building and scheduled monument that was built by John Dillwyn Llewelyn as a gift for his daughter Thereza on her 16th birthday.
The Penllergare Trust, in partnership with Dark Sky Wales, has been awarded funding from the Architectural Heritage Fund to restore the historic observatory and explore the potential of adding a planetarium to the building.
To stay informed and get involved, please follow the Penllergare Observatory group on Facebook. If you’d like to learn about the observatory, see here.
Weather forecast
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24/09/25
14° 1% -
24/09/25
12° 4% -
25/09/25
10° 0% -
25/09/25
9° 0%
Weather forecast for Gorseinon (2.0 miles away) updated 24/09/25 at 20:02.
Local light pollution
Penllergare Observatory is estimated to have light pollution levels similar to a semi-rural location based on the latest data from the VIIRS satellite.
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Urban
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Suburban
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Semi-rural
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Rural
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Dark site
The above demonstrates the estimated effect of light pollution - graphics created using Stellarium.
Best time to visit
The below chart shows when the skies will be at their darkest at this location and therefore the best time to visit. Moonlight is shown in light yellow and the Sun's twilight in light blue. Midnight on the date shown is shown as a white line with sunset to the left and sunrise the next morning to the right. A black background with stars shows the best times for stargazing. See our dark sky calendar for more details.
Wed 24th Sep
Thu 25th Sep
Fri 26th Sep
Sat 27th Sep
Sun 28th Sep
Mon 29th Sep
Tue 30th Sep
Find more dates
If you are planning to visit this location check our dark sky calendar to find out when is best!
CalendarEvents nearby
Stay and gaze nearby
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