The globular cluster（球状星团） Messier 107, also known as NGC 6171, is a compact and ancient family of stars that lies about 21 000 light-years away. Messier 107 is a bustling¹（熙熙攘攘的） metropolis²: thousands of stars in globular clusters like this one are concentrated into a space that is only about twenty times the distance between our Sun and its nearest stellar neighbour, Alpha Centauri, across. A significant number of these stars have already evolved into red giants, one of the last stages of a star's life, and have a yellowish colour in this image. Globular clusters are among the oldest objects in the Universe. And since the stars within a globular cluster formed from the same cloud of interstellar matter at roughly the same time — typically over 10 billion years ago — they are all low-mass stars, as lightweights burn their hydrogen fuel supply much more slowly than stellar behemoths（巨兽） . Globular clusters formed during the earliest stages in the formation of their host galaxies³ and therefore studying these objects can give significant insights into how galaxies, and their component⁴ stars, evolve.

Messier 107 has undergone intensive observations, being one of the 160 stellar fields that was selected for the Pre-FLAMES Survey — a preliminary survey（初步调查） conducted between 1999 and 2002 using the 2.2-metre telescope at ESO's La Silla Observatory⁵ in Chile, to find suitable stars for follow-up observations with the VLT's spectroscopic instrument FLAMES. Using FLAMES, it is possible to observe up to 130 targets at the same time, making it particularly well suited to the spectroscopic（光谱学的） study of densely⁶ populated stellar fields, such as globular clusters.

M107 is not visible to the naked eye, but, with an apparent magnitude of about eight, it can easily be observed from a dark site with binoculars⁷（双筒望远镜） or a small telescope. The globular cluster is about 13 arcminutes across, which corresponds to about 80 light-years at its distance, and it is found in the constellation⁸ of Ophiuchus, north of the pincers of Scorpius. Roughly half of the Milky⁹ Way's known globular clusters are actually found in the constellations¹⁰ of Sagittarius, Scorpius and Ophiuchus, in the general direction of the centre of the Milky Way. This is because they are all in elongated¹¹ orbits around the central region and are on average most likely to be seen in this direction.

Messier 107 was discovered by Pierre Méchain in April 1782 and it was added to the list of seven Additional Messier Objects that were originally not included in the final version of Messier's catalogue, which was published the previous year. On 12 May 1793, it was independently rediscovered by William Herschel, who was able to resolve this globular（球状的） cluster into stars for the first time. But it was not until 1947 that this globular cluster finally took its place in Messier's catalogue as M107, making it the most recent star cluster to be added to this famous list.

This image is composed from exposures taken through the blue, green and near-infrared filters by the Wide Field Camera (WFI) on the MPG/ESO 2.2-metre telescope at the La Silla Observatory in Chile.