The Soviet Vega 1 begins returning images of Halley's Comet and the first images of its nucleus.

The Union of Soviet Socialist Republics (USSR), commonly known as the Soviet Union, was a transcontinental country that spanned much of Eurasia from 1922 until it dissolved in 1991. During its existence, it was the largest country by area, extending across eleven time zones and sharing borders with twelve countries, and the third-most populous country. An overall successor to the Russian Empire, it was nominally organized as a federal union of national republics, the largest and most populous of which was the Russian SFSR. In practice, its government and economy were highly centralized. As a one-party state governed by the Communist Party of the Soviet Union (CPSU), it was the flagship communist state. Its capital and largest city was Moscow.

Vega 1 was a Soviet space probe, part of the Vega program. The spacecraft was a development of the earlier Venera craft. They were designed by Babakin Space Centre and constructed as 5VK by Lavochkin at Khimki. The name VeGa (ВеГа) combines the first two letters from the Russian words for Venus and Halley.

Halley's Comet is the only known short-period comet that is consistently visible to the naked eye from Earth, appearing every 72–80 years, though with the majority of recorded apparitions occurring after 75–77 years. It last appeared in the inner parts of the Solar System in 1986 and will next appear in mid-2061. Officially designated 1P/Halley, it is also commonly called Comet Halley, or sometimes simply Halley.