Definition: In this task, you are given a news article. Your task is to classify the article to one out of the four topics 'World', 'Sports', 'Business', 'Sci/Tech' if the article's main topic is relevant to the world, sports, business, and science/technology, correspondingly. If you are not sure about the topic, choose the closest option. Note that URLs in the text have been replaced with [Link].
Input: Worlds in Collision Rocky planets are born from dust. As dust bunnies congregate, they form larger rocky objects called planetesimals. These giant rocks collide as they circle their star, eventually growing into large terrestrial planets like the Earth, Mars and Venus.

Sci/Tech