Halley, the younger, was tutored privately in his home for many years until he entered Saint Pauls School. There, he excelled in all he did, becoming the captain of the school at the age of 15. At the age of 17, he entered Queen's College Oxford, already an expert astronomer. He carried with him the wonderful collection of astronomical instruments purchased for him by his father.
Within the next two years, he began working John Flamsteed, Astronomer Royal, assisting with observations at Oxford and Greenwich. When Flamsteed published his findings in "Philosophical Transactions of the Royal Society" in 1675, he mentioned Halley by name.
Besides the assistance he was providing to Flamsteed, Halley was also making observations of his own. On August 21, 1676 he observed an occultation of Mars by the Moon, which he published in "Philosophical Transactions of the Royal Society."
At some point in this time period, it seems that Edmund put his Oxford career on hold. While his mentor John Flamsteed began mapping the northern sky, Halley decided to map the southern sky.
Using funds secured from his father, and with the backing of King George II and other influential men, Edmund Halley set sail for St Helena Island, the southernmost point of the British empire.
It turned out that Saint Helena was not an ideal location for celestial observations. Still, during the year and a half spent there, Halley catalogued 341 southern hemisphere stars and discovered a star cluster in Centaurus. He also made the first complete observation of a transit of Mercury on November 7, 1677. Added to the improvements he made to the sextant and the observations of ocean and atmosphere he made during the journey, it was definitely not a wasted trip.