ephemerides
/ˌɛfəˈmɛrɪˌdiːz/
Definition
Tables or sets of calculated data providing the positions of celestial objects at regular intervals over a period of time.
Etymology
Derived from the Greek word 'ephēmeris', meaning 'daily' or 'diary'. It entered English via Late Latin, originally referring to journals or logs before being adopted in astronomy for daily planetary position records.
In the news
In this article, the word refers to the complex mathematical tables NASA uses to track the precise location of Voyager 1. These calculations are essential for predicting when the spacecraft will reach the specific distance of one light-day.
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