It is believed that certain planets move a little bit either out of alignment, so to speak. People blame the sun for this. They think that the Sun causes the planets to get sucked closer to it. People get scared when they think of this since the sun is so hot and it could be detrimental if the sun pulled a planet especially the Earth even the tiniest bit closer to the sun. However, the planets have stayed in the same place for billions of years.
Since they are rotating on their axis and orbiting, they are constantly moving which is believed to keep the Sun from pulling them closer. On the other hand, this is not to say that the planets won’t move further away from the Sun.