In the 1800/1801 edition of Connaissance des Temps (Knowledge of Time) — the oldest yearly publication of astronomical sky maps — Messier described why he started the now-famous Messier catalog:“What caused me to undertake the catalog was the nebula I discovered above the southern horn of Taurus on September 12, 1758, while observing the comet of that year. … This nebula had such a resemblance to a comet in its form and brightness that I endeavored to find others, so that astronomers would not confuse these same nebulae with comets just beginning to shine.”Although Messier originally created his catalog so that he could explicitly avoid observing deep-sky objects while he was comet hunting, today amateur astronomers from around the world rely on the Messier catalog to provide them with targets that are both visually stunning and easily locatable.As part of the Messier reboot, each Hubble image has an extended caption that beautifully describes the cosmic object, providing both historical and scientific context. Many of the most familiar objects are also shown in multiple wavelengths, revealing invisible structures that are both mysterious and fascinating. Finally, each image comes with a star chart and instructions that explain how amateur observers can locate each target.You can browse the entire Hubble version of the Messier catalog either on NASA's website or as an album on Flickr . Additionally, NASA will host a Facebook Live event about the new Hubble Messier catalog tonight at 8 p.m. EDT. During the event, the public will have the opportunity to ask questions to a panel of experts, while also learning more background on the Messier catalog.