Astronomy

Newgrange

Newrange is the best known but not the only astronomical monument in Ireland: a burial mound at Loughcrew, Co Meath, is aligned with the spring and autumn equinoxes; and a tomb at Knockroe, Co Kilkenny, is lit by the setting of the winter solstice sun. The burial mound is on top of a rocky outcrop and the entrance passage climbs uphill for 15 metres into the inner burial chamber. A special opening above the entrance is level with the floor of the inner chamber, and the rising Sun shines through this opening to light the chamber. Scratches on the underside of the stones suggest that various positions were tried before it was perfected. The winter solstice marks the end of the longest night and would be important in farming. But we can only guess at the full significance of this tomb-observatory and who, if anyone, would have been in the chamber to witness the solstice. The tomb was 'discovered' in the late 1600s but was not excavated until the 1960s. On December 21st 1967 at 8.58 am the archaeologists became the first modern people to witness Newgrange's astronomical phenomenon.

Image: Newgrange, Co. Meath (© Richard Gallagher)

Newgrange
Image: Newgrange, Co. Meath (© Richard Gallagher)

Newgrange

Newrange is the best known but not the only astronomical monument in Ireland: a burial mound at Loughcrew, Co Meath, is aligned with the spring and autumn equinoxes; and a tomb at Knockroe, Co Kilkenny, is lit by the setting of the winter solstice sun. The burial mound is on top of a rocky outcrop and the entrance passage climbs uphill for 15 metres into the inner burial chamber. A special opening above the entrance is level with the floor of the inner chamber, and the rising Sun shines through this opening to light the chamber. Scratches on the underside of the stones suggest that various positions were tried before it was perfected. The winter solstice marks the end of the longest night and would be important in farming. But we can only guess at the full significance of this tomb-observatory and who, if anyone, would have been in the chamber to witness the solstice. The tomb was 'discovered' in the late 1600s but was not excavated until the 1960s. On December 21st 1967 at 8.58 am the archaeologists became the first modern people to witness Newgrange's astronomical phenomenon.

Image: Newgrange, Co. Meath (© Richard Gallagher)

Enlarge image

Astronomy, it is said, is the oldest science. That is certainly true in Ireland: 5,000 years ago, a Neolithic farming community built what is arguably the world's oldest astronomical observatory at Newgrange by the River Boyne.

The elaborate burial mound is engineered so that at the winter solstice the rising Sun shines through an opening and lights up the inner chamber. Yet it was made by Stone Age people who had neither metal tools nor the wheel, and built 500 years before Egypt's pyramids and 1,000 years before Stonehenge.

People have always looked at the skies and wondered about the stars and planets. But the Universe does not easily give up its secrets, and modern astronomy had to wait until the telescope arrived in the 17th century. Astronomy began in earnest with powerful instruments in the 19th century, and Irish astronomers were to the fore of this activity.

Sir William Rowan Hamilton

Hamilton (1805-65) was arguably the greatest Irish scientist. He made many contributions to physics, especially in mechanics and optics, as well as inventing quaternion algebra. His greatest work is his general theory of dynamics. His Hamiltonian operator (H) was crucial to the development of quantum mechanics, and today it is used by physicists, engineers and even economists. Hamilton spent all his working life as Astronomer Royal at Dunsink Observatory.

Image: Sir William Rowan Hamilton, MRIA, 1805-1865 (© RIA)

Sir William Rowan Hamilton
Image: Sir William Rowan Hamilton, MRIA, 1805-1865 (© RIA)

Sir William Rowan Hamilton

Hamilton (1805-65) was arguably the greatest Irish scientist. He made many contributions to physics, especially in mechanics and optics, as well as inventing quaternion algebra. His greatest work is his general theory of dynamics. His Hamiltonian operator (H) was crucial to the development of quantum mechanics, and today it is used by physicists, engineers and even economists. Hamilton spent all his working life as Astronomer Royal at Dunsink Observatory.

Image: Sir William Rowan Hamilton, MRIA, 1805-1865 (© RIA)

Enlarge image

Dunsink Observatory was built in 1783 by Trinity College Dublin. Located on a hill north of the city, it is Ireland's oldest scientific institution and today is part of the Dublin Institute for Advanced Studies (DIAS). Among the astronomers who worked there were two great 19th-century scientists, Sir William Rowan Hamilton and Sir Robert Ball.

Astronomers no longer work there - they have moved to city offices and use remote access to instruments located around the world and even in space.

Armagh Observatory opened in 1791 and is Northern Ireland's oldest scientific institution. Weather was important to astronomers, because it determines how much they can see, and the first instrument to measure wind speed was invented at Armagh by Thomas Romney Robinson in 1850. The observatory also has Ireland's longest continuous weather records, an important source for scientists studying climate change.

Outside of professional scientists at Dunsink and Armagh, the 19th century was the era of the amateur. In astronomy that generally meant wealthy landowners who could afford a private observatory. And the greatest of these was at Birr Castle where, in 1845, William Parsons built the world's biggest telescope.