8. Magnetic Field
It’s crazy we went so long without mentioning a crucial thing every planet needs to sustain human life. A magnetic field may be one of the biggest things needed because of what it does to help. For example, the biggest thing it does is prevent solar flares from hitting the Earth as well as the sun from burning up the atmosphere overall.
Mars does not have a global magnetic field like we do, which is why it has such a thin atmosphere. This prevents humans from living there without spacesuits. While our new planet may not need a magnetic field as extremely huge as the Earth’s, it will need to be sizable enough to protect the planet from its sun.