aphelion
UK[əˈfiːliən]US[əˈfiːliən]
n
the point in the orbit of a planet, asteroid, or comet at which it is furthest from the sun.
Morpheme Breakdown
ap
helion
ap
away from
helion
sun
Etymology
the term 'aphelion' is a modern scientific coinage derived directly from ancient greek components. it combines the prefix 'apo-', meaning 'away from', with 'hēlios', the personification and word for the sun. this formation follows the model of other astronomical terms like 'perihelion' (near the sun). thus, the word's literal construction, 'away from the sun', transparently and logically describes the orbital point it denotes.
Analysis
Structure: ap (away from) + helion (sun)
ap (prefix of greek origin, meaning 'away from' or 'off'); helion (from greek 'hēlios', meaning 'sun')
Examples
earth reaches its aphelion in early july each year.
the comet's velocity is slowest when it is at aphelion.
calculating the aphelion of an orbit requires precise astronomical measurements.