341 stars cataloged by the Astronomer Edmond Halley 341 year ago on St Helena.
It was in the year of 1676 that 20 year old Oxford undergraduate, Edmond Halley left the esteemed University to embark on a project that would advance him to Astronomer royal status.
Halley’s family fortunes meant that his Father (also called Edmond Halley) could afford a ‘fine collection of instruments’ to assist in his son’s expertise.
It is thought that his work with the famous Flamsteed, and the launch of the Royal Observatory at Greenwich (1675) propelled Halley to undertake the task of mapping the southern hemisphere stars. This would complement Flamsteed’s mapping of the northern hemisphere.
St Helena, being the Southern-most territory under British rule, came to be the preferred observation grounds. So began the long journey South.
Halley’s expedition was sponsored by his Father and Charles II and supported by the East India Company who governed the Island at the time.
It was in November of 1677, just under 3 and half centuries ago, that Halley and his colleague arrived to St Helena and set up station for 18 months.
It is documented that the weather proved trying to the young Astronomer, and the task set before him but in spite of this, he was said to have successfully cataloged 341 southern hemisphere stars and made a discovery of a star cluster in Centaurus.
Halley’s Observatory site (although not officially documented) is located fairly central on the Island in close proximity to the Peaks, the highest point above sea level. Although no consensus of the actual site can be found, it was Astronomer David Gill who after visiting in 1877 reportedly felt this location was “without doubt” the most likely site. There was no other plausible sites found. Today a monument stands on the mount in honor of Halley’s visit and his work.
It is written that observations at the site led Halley to some of his most important and perhaps least appreciated discoveries: The Catalogus Stellarum Australium- the catalog of the Southern Hemisphere stars; the discovery of the Stellar Proper Motion – that stars move; and the transit of Mercury. From his observations he proposed using the transit of Mercury and Venus to determine the distance from the Sun and later, the scale of the solar system by use of Kelper’s third law.
On his return to England, he was gained recognition for these works, and at such a young age was able to establish himself among key influences of his era.
Today St Helena is arguably still a prime observation spot for the night sky. Nestled in the middle of the South Atlantic with relatively low light pollution the solar system glistens. The Island is now undertaking measures to become dark skies accredited and to revive the interest of our astronomy offering and the historic visits of Astronomers who paved the way – Halley being a key figure among these.