St. Helena Magnetic Observatory

St Helena Magnetic Observatory once stood at Longwood on the remote island of St Helena in the South Atlantic, one of a chain of stations built by the Royal Society to map the Earth's magnetism across the British Empire.

About St Helena Magnetic Observatory

Unlike a stargazing observatory, this station was built to measure the Earth's magnetic field rather than the night sky. It stood at 586 metres elevation at Longwood, chosen partly because the island sat close to a point of unusually low magnetic field intensity, and partly because Longwood's deep soil reduced interference from magnetic rock nearby.

History

The observatory was established in February 1840 under Lieutenant-Colonel Edward Sabine, as part of the Royal Society's "Magnetic Crusade" - a coordinated effort to set up magnetic observatories across the British Empire. It also recorded meteorological data and published its magnetic observations in several volumes starting in 1847. The station closed in 1849, its equipment dismantled soon after; the building was later repurposed as St Mark's Church Hall. Data gathered here later helped show that the Earth's magnetic field had shifted by around 30 degrees over 250 years.

Location & getting there

St Helena is a remote island in the South Atlantic, and Longwood, where the observatory stood, sits at 586 metres above sea level on the island's high ground.

Visiting St Helena Magnetic Observatory

The original station no longer operates, and its building now serves as a church hall, so there isn't a working observatory here to tour today. Visitors interested in St Helena's scientific history can still see Longwood and its surroundings as part of a wider visit to the island.

See your named star from here

St Helena's isolation in the South Atlantic makes for some remarkably dark skies. Browse the star catalogue or choose a naming package to find the coordinates of a star named through star-register.eu, then look for it from the island on a clear night.