Johann Abraham Ihle

Lore & Background

Johann Abraham Ihle was born on 14 June 1627 in Leipzig, where he lived his entire life. He worked as a postal clerk, but pursued astronomy as an amateur. On 26 August 1665, while observing Saturn in Sagittarius with a small refractor telescope, he discovered what is now known as the globular cluster M22. He described it as a 'composite nebula between the head and the bow of the archer onto which a great number of faint stars was projected,' not recognizing it as a globular cluster, a concept that would not be understood until Charles Messier's observations of Messier 4 in 1764.

Ihle was friends with astronomers Gottfried Kirch and Johannes Hevelius, and was in contact with Erhard Weigel. In the 1680s, he observed sunspots alongside contemporaries such as Hevelius, John Flamsteed, and Jonas Moore. He continued his astronomical work, staying in close contact with Kirch, until he retired at age 68 in 1695. Ihle died either in 1699 or shortly after.

Reader's Guide

Johann Abraham Ihle's significance lies in his discovery of M22, the first known globular cluster, which he observed in 1665. Though he misidentified it as a nebula, his observation predated the understanding of globular clusters by nearly a century. His work as an amateur astronomer, while holding a day job as a postal clerk, exemplifies the contributions of non-professional observers to early astronomy. His inclusion in the 'red list' of sunspot observers alongside figures like Hevelius and Flamsteed highlights his role in building a continuous record of solar activity during the 1660s–1680s. The disputed claim regarding Abraham Hill underscores the challenges of historical attribution, but the consensus rejects it as speculation. Ihle's legacy is tied to his careful observations and his network of correspondence with leading astronomers of his time, such as Kirch and Hevelius, which helped sustain his work until his retirement in 1695.

Did You Know?

• Ihle discovered the globular cluster M22 on 26 August 1665 while observing Saturn.
• He misidentified M22 as a nebula, as globular clusters were not understood until Charles Messier's 1764 observations of Messier 4.
• Ihle was a postal clerk by profession and lived his entire life in Leipzig.
• In the 1680s, he observed sunspots alongside astronomers such as Hevelius, Flamsteed, and Jonas Moore.