Micrometer (µm): The micrometer, also known as the micron, is equal to one one-millionth of a meter (0.000001 meters). It is used in scientific research, especially in fields like microscopy and nanotechnology.
Light Year: A light year is the distance that light travels in one year through a vacuum, approximately equal to 9.461 trillion kilometers (about 5.878 trillion miles). It's used to measure vast cosmic distances.