Detailed Instructions: Based on the information present in the given passage, you need to write a correct answer to the given question. A correct answer is one that correctly and completely answers the question. Do not write answers that address the question partially or incorrectly. The correct answer must be contained in the given paragraph.
Problem:Paragraph- Sent 1: The center of an atom is held together by powerful forces.
Sent 2: This gives them a huge amount of stored energy.
Sent 3: This type of energy is called nuclear energy.
Sent 4: This energy can be released and used to do work.
Sent 5: This happens in nuclear power plants where they split apart the nucleus of an atom.
Sent 6: This splitting apart is called nuclear fission.
Sent 7: Another type of nuclear energy happens in the Sun.
Sent 8: Here the atoms nuclei are not split apart.
Sent 9: Instead, the nuclei of the atoms are fused, or joined together.
Sent 10: This process is called nuclear fusion.
Sent 11: Some of the suns energy travels to Earth.
Sent 12: This energy from nuclear fusion warms the planet and provides the energy for photosynthesis. 
Question: What is the stored energy at the center of the atom called?.
Solution:
Nuclear energy.