The annual treasury for sky-watchers and stargazers, including references and a variety of fascinating articles. The Yearbook of Astronomy series is renowned for its comprehensive jargon-free monthly sky notes and authoritative sky charts that enable backyard astronomers and sky-gazers everywhere to plan their viewing of the year’s eclipses, comets, meteor showers, and minor planets, as well as detailing the phases of the moon and visibility and locations of the planets throughout the year. Every annual edition also includes a variety of entertaining and informative articles. Among the wide-ranging articles in this 2021 edition are: Male Family Mentors for Women in Astronomy Henrietta Swan Leavitt and Her Work Solar Observing Obsolete Constellations Lunar Volcanism Pages From the Past: Collecting Vintage Astronomy Books Maori Astronomy in Aotearoa-New Zealand, and more In addition you’ll find the first in a series entitled Mission to Mars: Countdown to Building a Brave New World, scheduled to appear in the Yearbook throughout the 2020s to keep you fully up to date with the ongoing investigations, research, and preparations that are already underway, as well as those in the planning phase, geared towards sending a manned mission to Mars around the end of the decade. We are at the start of what promises to be an exciting journey—and the Yearbook of Astronomy continues to be an essential companion.