heliopause
/ˈhiːliəˌpɔːz/
Definition
The outer boundary of the Sun's influence where the solar wind is stopped by the interstellar medium, marking the threshold between the solar system and interstellar space.
Etymology
The term is derived from the Greek 'helios' (sun) and the Greek 'pausis' (a stopping or cessation). It was coined in the 20th century to describe the point where solar wind halts.
In the news
The article uses the heliopause as a physical landmark to contrast with the abstract 'one light-day' milestone. It notes that Voyager 1 crossed this boundary in 2012 when entering interstellar space.
NASA has calculated, to the precise second, when Voyager 1 will be exactly one light-day from Earth: 2:16 a.m. on 18 November 2026, at a distance of 16,094,799,096 miles — a number that would have been science fiction when the probe launched in 1977
Read the full article ↗Space Daily