Sun, the source of all life in our solar system, certainly earns its own Language Day article! From the linguistic point of view, you can easily see the similarities in several of the European languages in the words we have for sun, be they Germanic, Latin or Slavic languages.
The Romans replaced the Greek word for sun, Helios, with the Latin Sol, a root word that continues to refer to the sun in the present day, but sol itself came from the Proto-Indo-European sóh₂wl̥. And we are of course pretty familiar with both prefixes (helio and solar).
CHINESE ?? tàiyáng 太阳
DANISH ?? sol - from Old Norse sól ← Proto-Germanic sōwulą, *sōwulō (sun) ← Proto-Indo-European sóh₂wl̥
DUTCH ?? zon
ENGLISH ????????????? the Sun - from the Old English sunne, which likely derives from the old Germanic sunne.
ESTONIAN ?? päike - derived from the word päev (day).
FINNISH ?? aurinko - used since 1500s (instead of päivä, day), but origin unclear. Possibly from the Latin aurum (gold) or aurora (dawn). Or a variant of auer. Mikael Agricola might have had in mind a piece of gold (-ko being a diminutive suffix) for that is what the sun sometimes looks like.
FRENCH ?? soleil - from the Latin sol
GERMAN ?? die Sonne - from the old Germanic sunne.
GREEK ?? ήλιος (ílios)
HAWAIIAN lā -
HUNGARIAN ?? Nap -
ICELANDIC ?? sól - from Old Norse sól ← Proto-Germanic sōwulą, *sōwulō (sun) ← Proto-Indo-European sóh₂wl̥
IRISH ?? ghrian
ITALIAN ?? il sole - from the Latin sol
JAPANESE ?? Taiyō 太陽 - from Middle Chinese 太陽 (_ tʰɑi jɨɐŋ_)
KOREAN ?? taeyang 태양 - from Sino-Korean word 太陽, 太 (great) + 陽 (yang = sun, light)
LATIN solis - from Proto-Indo-European sóh₂wl̥
LATVIAN ?? saule - from Proto-Indo-European sóh₂wl̥
LITHUANIAN ?? saulė - from Proto-Indo-European sóh₂wl̥
NORWEGIAN ?? sol - from Old Norse sól ← Proto-Germanic sōwulą, *sōwulō (sun) ← Proto-Indo-European sóh₂wl̥
TAGALOG ?? araw - from Proto-Malayo-Polynesian qaləjaw
POLISH ?? słońce - from Proto-Slavic sъlnьce ← Proto-Indo-European sóh₂wl̥
PORTUGUESE ?? sol - from the Latin sol
RUSSIAN ?? солнце (solnche) - from Old East Slavic сълньце (sŭlnĭce) ← from Proto-Slavic (sъlnьce) ← Proto-Indo-European sóh₂wl̥
SPANISH ?? sol - from the Latin sol
SWAHILI jua
SWEDISH ?? solen - from Old Norse sól ← Proto-Germanic sōwulą, *sōwulō (sun) ← Proto-Indo-European sóh₂wl̥
TURKISH ?? güneş - from Proto-Turkic günei (sun, sunny place)
WELSH haul - from Proto-Indo-European sóh₂wl̥
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