Final answer:
The largest object in space that can have an irregular shape is about 400 kilometers in diameter. Objects larger than that will be approximately spherical due to gravity.
Step-by-step explanation:
The largest object in space that can have an irregular shape is determined by gravity. Gravity pulls objects into the most efficient shape, which is a sphere. For silicate bodies, such as asteroids, the limiting diameter is about 400 kilometers. Objects larger than that will always be approximately spherical, while smaller ones can have various shapes.