Your animal does not change; what changes is the year around it. 2039 carries the number 5 (from 2 + 0 + 3 + 9), which sets the tone the Rat is operating inside.
Those born in the Year of the Rat are quick-witted, resourceful and adaptable. This makes them reliable company, natural problem-solvers and people others instinctively trust.
A year reading is about conditions, not Fate. The question is what 2039 makes easier and harder for the way the Rat already works.
More on the Rat: Rat zodiac · Rat in 2026 · the number 5 · zodiac signs · tarot readings · numerology
Years are not good or bad in the Chinese system — the annual cycle emphasises certain things and de-emphasises others. Whether that reads well depends on what you are trying to do.
No. Your animal is fixed at birth by your lunar birth year. The year animal is the cycle around you.
On Chinese New Year, which falls in late January or February — not on 1 January. Check the exact date for that year.