Tuesday

Tuesday is the first weekday in English whose name departs from the Latin planet entirely. Dies Martis, Mars's day, became Tiw's day among the Germanic peoples through interpretatio germanica, the practice of substituting a native god judged equivalent to the Roman one being named. Tiw, a war and law god known more fully in Old Norse as Tyr, was read as Mars's Germanic counterpart because both presided over combat and, in Tyr's case, the binding oaths that made organised warfare and legal order possible, a somewhat broader portfolio than Mars's alone but close enough for the day name to transfer.

The Romance languages took the opposite path and kept the Latin planet directly: martedi in Italian and mardi in French both preserve Mars by name without any Germanic substitution, since the Romance tongues descend from Latin itself rather than layering a translation over an inherited planetary system the way English and German did. The split between the two naming strategies, Latin retained in the Romance languages and Germanic gods substituted in English and its relatives, runs consistently through Tuesday, Wednesday, Thursday and Friday, making this pair of naming conventions one of the clearest linguistic fossils of the old planetary week's spread across two different language families.

Sources Norse Mythology: A Guide to the Gods, Heroes, Rituals, and BeliefsJohn Lindow with Deutsche MythologieJacob Grimm

Tuesday carries Mars's significations in the older astrological literature: energy, courage, assertive action and, on the more difficult side of the same planet's nature, conflict, aggression and haste. Because Mars was read as one of the two malefic planets alongside Saturn, medieval and Renaissance astrological handbooks generally counsel caution around undertakings begun on a Tuesday that require patience or diplomacy, while favouring the day for anything that genuinely calls for boldness, physical exertion or a direct confrontation of an obstacle.

The pairing of planetary day and planetary hour, where a working matched to both was held to gain strength from the doubled attribution, made a Tuesday hour of Mars, falling twice in the daylight and twice at night across the twenty four hour cycle, the most concentrated window for operations specifically concerned with Mars's domain, whether that meant literal martial activity, competitive contests, or simply summoning the resolve to begin something difficult.

Sources A History of Western AstrologyNicholas Campion with Grimoires: A History of Magic BooksOwen Davies