I have been studying astronomy and astrophysics for about 2 years now, though on my own time and by my self. A recent question came into my mind, Can arctic planets exist close to their star? Now, in my understanding of planetary science, in order for a planet to be cool and close to the sun, it would need a pretty thick atmosphere, and a strong magnetic field in order to protect that atmosphere from the star's solar winds. Instantly, mercury came to mind, so I tried to find out why mercury doesn't have a thick atmosphere, and came out understanding that mercury's magnetic field is not very strong, and the sun's solar winds blow away it's atmosphere, but the magnetic field does protect it from some solar winds. I can understand why mercury has a weak magnetic field, because it is the smallest planet and has the least mass. So I directed my study to the cores of other planets, I know venus's magnetic field is significantly weaker than earth's, because the effect of magnets weakens the hotter it gets, and on venus, where it is hot enough to melt lead, it would have a pretty weak magnetic field. I just can't understand how it holds onto it's atmosphere, with strong solar winds and a weak magnetic field. To make matters worse, I tried to find out why mars still has a magnetic field. I was taught that a magnetic field generates when a planet has a solid inner core and a liquid outer core, because the flow of liquid iron creates a magnetic field. Mar's core has been cooled since the creation of our solar system, but yet it still generates a magnetic field, though being geologically inactive. How? Though the title only holds one of the questions I had, may you answer the ones I couldn't fit in the title?