That’s right it is not always Polaris. Over a human lifetime Polaris will always be our north star, but in the year 14,000, it will be the bright star Vega. This is due to the tilt of the Earth’s axis, which precesses like a spinning top, albeit much more slowly, over a 32,000 year period.
How do we measure the rotation speed of a planet? Exactly as you would expect. Watch the surface, look for markable features, and time how long it takes until those features pass the same point again in the future. But how can we possibly nail down this information when the planet has little to no visible surface features. Gas giant planets are great examples of this. Jupiter is a bit easier since it has plenty of storms and separated cloud layers along the planet’s rotation axis, but the other three are much tougher. Aside from hard-to-spot features, gas giants also...
It’s been cold lately. The temperature has fallen somewhere between Hoth and Pluto, and it doesn’t look like it’s going to change any time soon. It seems we complain about the weather no matter the season. It’s too hot, too cold, too wet, too dry, too bright, too dark. We do have a lot of variation in the seasons, but compared to some other planets, Earth is pretty mild in its climate. One such case is the recently discovered Kepler 432b. A massive planet six times heavier than Jupiter with a comparable size, it orbits closer to its parent star than Mercury...
