I wonder if they picked pronouns for the planets in accordance with the associated gods of Greco-Roman mythology? IIRC, the Greco-Roman sun gods were all male (e.g. https://en.wikipedia.org/wiki/Helios).
If I'm correct they'd use male pronouns for the sun, Mars, and Jupiter; and female pronouns for Earth, the Moon (Luna), and Venus.
It seems more likely to me that people just kept using the latin genres since old scientific literature was in latin.
One place you see this is in terms relating to food. Words relating to rustic activities like agriculture and raising animals such as "cow" tend to have German roots. While culinary words like beef and veal tend to have french roots.
Mars, Jupiter, etc. are used as proper nouns, without a definite article nor a gender. If any, we use the male gender, as in "the (m) planet Venus".
"sun (n.) [...] Old English sunne was feminine (as generally in Germanic), and the fem. pronoun was used in English until 16c.; since then masc. has prevailed." [1]
"moon (n.) [...] A masculine noun in Old English." [2]
[1] https://www.etymonline.com/search?q=sun [2] https://www.etymonline.com/search?q=moon