Isn't it obvious that life exists in almost every galaxy?
I’d say yes, it’s almost certain, but there’s no evidence of this. Currently the earth is the only place in the universe that we know harbors life and it’s impossible to extrapolate a trend from a single data point. The problem is exacerbated by our lack of understanding about how life originally arose - whether it was a single extremely unlikely event or happened more than once on ancient earth. The more we learn about molecular biology, the possible niches life could inhabit elsewhere in our solar system, and extra-solar planets, the more the likely it seems that we’ll find life elsewhere in the universe. These discoveries feed into the Drake Equation, which is formula for calculating the number of civilizations in the galaxy based on a chain of probabilities. Rough estimates put the number at about 10,000 civilizations in the galaxy, but it’s all based on guesses. However, we are starting to narrow down some of the ranges. One of the big unknowns was the number of planets that most stars have. It turns out that planets are very common, and earth-like planets aren’t completely rare. That makes things more likely.But all this does raise a question: if the universe is teeming with life, where are all the signs of alien civilizations? I suspect that the answer is that intelligent life is probably usually very short-lived and fleeting. The human race is already in the process of destroying our own planet, causing mass extinctions that may one day lead to the collapse the of the earth’s ecosystems with the probable end of civilization as a result. Perhaps that’s a common thread throughout the universe and simply an inevitable consequence of intelligent beings that have powerful control over their environments.There are other possible, less depressing, explanations. We may soon discover technology that would allow communications with other civilizations in some as-yet unknown way, or that all civilizations come to realize that communication with others is not a risk worth taking (read: The Three Body Problem trilogy).I really hope alien life, probably microbial, is discovered off the earth in my lifetime. It would be a huge scientific and cultural breakthrough and I can’t wait. Perhaps then we can start treating our world with a bit more respect.
Theoretically, would it be possible for any planet or exoplanet to have more than four seasons?
I would challenge you to consider that most places on Earth don’t experience 4 seasons, that’s just an idea we’ve given to them.Where I live there is a growing season and a non-growing season, otherwise known as Summer and Winter with transitions between them. Spring is just early Summer, and Fall is just early Winter.The real question would be … what is a season?From … Season - Wikipedia …“In temperate and subpolar regions, four calendar-based seasons are generally recognized: spring, summer, autumn or fall, and winter. Ecologists often use a six-season model for temperate climate regions: prevernal, vernal, estival, serotinal, autumnal, and hibernal. Many tropical regions have two seasons: the rainy, wet, or monsoon season and the dry season. Some have a third cool, mild, or harmattan season.”These are arbitrary lines. Different plants have different germinations, different growth periods, different requirements for development. Animals calve at different times, sometimes regardless of ‘season’ (like us humans).If you’re looking for exoplanet extremes, consider a planet that maintains an axial tilt (like the Earth does, as they say, Jesus isn’t the reason for the season, it’s the axial tilt) but has a highly variable eccentric orbit, so sometimes it’s close to its star while tilted so it receives overhead sunlight, while sometimes it’s far from its star while tilted so it receives overhead sunlight … different kinds of summer.Also consider that many climates can be approximated by increases in altitude. Going up a slope in New Zealand, for example, you can swim on the beach in the morning and ski on snow in the afternoon … and if you can have those different climates in the same location plus transitions between them over time, I can imagine, if you wanted to, you could over the course of several orbits have a multitude of ‘seasons’. It just depends on how you want to define them.