Convert Earth's Distance from Sun (AU (es)) to Femtometer (fm) instantly.
About these units
Earth's Distance from Sun (AU (es))
The average distance from the Earth to the Sun is approximately 1 astronomical unit (AU) = 149,597,870.7 km. This distance forms the basis for measuring interplanetary distances within the solar system. Astronomers rely on the AU to calculate orbital periods, planetary alignments, and the intensity of solar radiation at different planets. Its precise measurement comes from radar ranging to planets, spacecraft telemetry, and observations of orbital mechanics. The AU provides a human-scaled reference for the vast distances in the solar system, bridging Earth-based intuition with astronomical scales. It is a cornerstone unit in celestial mechanics and planetary science.
Femtometer (fm)
A femtometer, equal to 10⁻¹⁵ meters, is the scale at which the structure of atomic nuclei becomes measurable. Also known historically as a "fermi," this unit is used extensively in nuclear physics to describe the radii of protons, neutrons, and nuclei, which typically span 1–10 femtometers. At this scale, the strong nuclear force dominates interactions, and classical intuition breaks down almost entirely—quantum mechanics provides the only meaningful framework. The femtometer also plays a role in high-energy particle experiments, where the wavelengths of probing particles (like high-velocity electrons) may be expressed in femtometer increments. These small wavelengths allow researchers to resolve sub-nuclear structures. While invisible to any optical instrument, distances in the femtometer range can be inferred through scattering experiments, such as those performed in particle accelerators.