Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Nature of Planetary Matter and Magnetic Field Generation in the Solar
  System   Understanding the nature of the matter comprising the Solar System is crucial
for understanding the mechanism that generates the Earth's geomagnetic field
and the magnetic fields of other planets and satellites. The commonality in the
Solar System of matter like that of the inside of the Earth, together with
common nuclear reactor operating conditions,forms the basis for generalizing
the author's concept of nuclear geomagnetic field generation to planetary
magnetic field generation by natural planetocentric nuclear fission reactors.

15
The categories of this paper are: nucl-ex
12
The categories of this paper are: nucl-th
31
The categories of this paper are: ao-sci
27
The categories of this paper are: comp-gas
37
The categories of this paper are: supr-con
32
The categories of this paper are: atom-ph
4
The categories of this paper are: cond-mat
17
The categories of this paper are: q-fin
0
The categories of this paper are: hep-ph
18
The categories of this paper are: econ
5
The categories of this paper are: gr-qc
7
The categories of this paper are: hep-th
10
The categories of this paper are: q-bio
28
The categories of this paper are: alg-geom
21
The categories of this paper are: adap-org
11
The categories of this paper are: hep-lat