The star could be hundreds of millions of years older or younger than the Sun.
Even if the star was exactly like the Sun, and had a planet with exactly the same initial conditions as Earth, life need not have arisen. If it did arise, then it could have followed an entirely different course.
Surely such huge episodic events such as earthquakes, volcanism, and asteroid impacts would have occurred at different times.
Continents would be shaped differently.
The presence of absence of a satellite comparable to the Moon would have made a big difference.
When the Moon formed, it was about six times as close as it is today. Since tidal forces decrease as the THIRD power of distance, it is clear that tides were about 216 times as high as they are today. The angular momentum that now resides in the Moon would have been in the Earth's rotation, implying a day of roughly 6 to 8 hours. That means a permanent tsunami washed around the globe every 6 to 8 hours, causing thorough mixing of all ocean waters. This was a circumstance that was overwhelmingly important to the development of Life.
In short, even if starting conditions were as nearly identical as possible, the planet at Earth's distance (if such exists) would have followed an entirely different course of Evolution.
David F Mayer
- The situation will not be exactly the same. — David F Mayer, Sun Apr 29 4:04pm