Without a sun its going to get very cold on the surface of the planet. Likely it will be frozen solid, but perhaps with a bit of Volcanic activity, it might be warm enough in places for life to survive. Eventually it could drift into another solar system and perhaps collide with other planets. Venus for example spins the opposite way to the rest of the planets, https://en.wikipedia.org/wiki/Venus It is thought that Mars and Earth both have had massive collisions in their early history, and is where the moons come from. https://medium.com/s...s-a8a1832104dc
Thank you. I was thinking I have read about drifting planets but thought maybe I'd dreamed it. I had not thought of volcanic activity. Stored up heat in what we eventually call lava? I once went looking for a good book about volcanoes- what causes them to form. Not so much activate ss their source and what forms that. All I found were children's books. Who knows. Maybe one of them tells but I hoped for more.
But, yes, we need heat for life - on Earth, at least. We can't be sure on some faraway drifting planet. Thank you.