Astronomical Unit
An astronomical unit (AU) is a unit of distance used in astronomy to describe the average distance between the Earth and the Sun. It equals about 149.6 million kilometers (or about 93 million miles). The AU is useful for measuring distances within our solar system, such as the distance from Earth to other planets. For example, Mars is about 1.5 AU from the Sun. Using the AU makes it easier to understand and compare distances between planets without dealing with very large numbers. The symbol for astronomical unit is "AU".
Planck Length
The Planck length is the smallest meaningful unit of length in physics, representing a fundamental scale at which classical ideas about gravity and space-time break down and quantum effects dominate.
It is defined as approximately 1.616 × 10⁻³⁵ meters.
The Planck length is derived from fundamental constants: the speed of light, Planck’s constant, and the gravitational constant.
It sets a theoretical limit below which the very concepts of space and distance may lose conventional meaning.
Used mainly in theories of quantum gravity and string theory.
Key facts:
1 Planck length ≈ 1.616 × 10⁻³⁵ m
Smallest scale in quantum physics and cosmology
Represents a scale where quantum effects of gravity become significant
The Planck length is crucial for understanding the fabric of the universe at its most fundamental level.
No conversions available for length.