"So far as we know," declared the scientific journal Nature in September 1877, "these are the first observations of a satellite of Mars in these islands."
It was referring to a report from a Dr Wentworth Erck, who had made the sighting through his telescope at Shankhill, in Co Dublin, and indeed his was only two weeks away from being the first such observation in astronomical history. This honour, however, went to a young American called Asaph Hall, who sighted the first of the two moons of the planet Mars 120 years ago today, on August 11th, 1877.
The notion that the planet must have two moons came originally from Johannes Kepler, who was of the view that the rhythmic order of the universe demanded it. In the early 1600s he wrote to congratulate his colleague Galileo on discovering the moons of Jupiter, saying: "I am so far from disbelieving in the discovery of the four circumjovial planets, that I long for a telescope to anticipate you, if possible, in discovering two around Mars - as the proportions seem to require six or eight around Saturn and perhaps one each around Mercury and Venus."
But even if they were suspected to exist, the moons of Mars proved decidedly elusive. Its orbit relative to Earth is such that conditions favourable for a sighting occur every 15 to 17 years. A systematic but unsuccessful search had been carried out on the previous such occasion in 1862, but the power of a new 26-inch reflecting telescope at the Washington Observatory under the stewardship of Asaph Hall greatly improved the chances of success when the next auspicious period came along in the autumn of 1877.
Hall spotted the first satellite at 2.30 a.m. on August 11th, and the second less than a week later on August 17th. He called them Phobos and Deimos, or Fear and Terror, the mythological sons of the Mars, the Roman god of war. They are only tiny things: Phobos, the larger of the two, is 17 miles in diameter and Deimos is only nine miles across - not much bigger, for example, than Valentia Island.
Recalling his success, Hall later admitted: "The chance of finding a satellite appeared to be very slight, so that I might have abandoned the search had it not been for the encouragement of my wife." But one suspects even more than just encouragement.
A femme redoutable was Mrs Angelina Stickney Hall, and as one of her sons remarked in later years: "She insisted upon her husband's discovering the satellites of Mars."