- Messier 10 or M10 (also designated NGC 6254) is a globular cluster of stars in the equatorial constellation of Ophiuchus. The object was discovered by the French astronomer Charles Messier on May 29, 1764, who cataloged it as number 10 in his catalogue and described it as a “nebula without stars”. In 1774, German astronomer Johann Elert Bode likewise called it a “nebulous patch without stars; very pale”. Using larger instrumentation, German-born astronomer William Herschel was able to resolve the cluster into its individual members. He described it as a “beautiful cluster of extremely compressed stars”. William Parsons, 3rd Earl of Rosse thought he could distinguish a dark lane through part of the cluster. The first to estimate the distance to the cluster was Harlow Shapley, although his derivation of 33,000 light years was much further than the modern value.
- Eta Aquilae (Wikipedia)
Eta Aquilae (η Aql, η Aquilae) is a multiple star in the equatorial constellation of Aquila, the eagle. It was once part of the former constellation Antinous. Its apparent visual magnitude varies between 3.49 and 4.3, making it one of the brighter members of Aquila. Based upon parallax measurements made by the Gaia spacecraft on its third data release (DR3), this star is located at a distance of roughly 272 parsecs (890 light-years). The primary component is a Classical Cepheid variable.