'Yupiter' was a Soviet offensive, more formally known as the 'Mozhaysk-Vyaz’ma Offensive Operation', against Generalfeldmarschall Günther von Kluge’s Heeresgruppe 'Mitte' in the area to the west and north-west of Moscow within the 'Rzhev-Vyaz’ma Strategic Offensive Operation', which was the second Soviet strategic offensive of the 'Great Patriotic War' of World War II after the 'Moscow Strategic Offensive Operation' (10 January/28 February 1942).

The other elements of the 'Rzhev-Vyaz’ma Strategic Offensive Operation' were the 'Sychyovka-Vyaz’ma Offensive Operation (8 January/28 February), the 'Toropets-Kholm Offensive Operation' (9 January/6 February), the 'Vyaz’ma Airborne Operation' (18 January/28 February), the 'Rzhev-Vyaz’ma Offensive Operation' (3 March/20 April) and the 'Demyansk Offensive Operation 2^nd Phase' (7 January/20 May).