The movie Contact makes mention of Jansky - "Reading over a hundred Janskys". Thought it was a made up unit at the time
This is true for all SI units. Newton, watt, and joule are all lowercase, unless they appear at the beginning of a sentence or when you're referring to the original scientists.
People often get confused because the abbreviations for those units are capitalized.
[0] https://www.iau.org/publications/proceedings_rules/units/