Light Year
A light year is a unit of distance used in astronomy to measure how far light travels in one year. Light moves extremely fast—about 299,792 kilometers per second—so in one year, it travels roughly 9.46 trillion kilometers (or about 5.88 trillion miles). Light years help scientists express the huge distances between stars and galaxies. For example, the nearest star to Earth, Proxima Centauri, is about 4.24 light years away. The term “light year” can be confusing because it sounds like a measure of time, but it actually measures distance.
Ångström
An ångström (symbol: Å) is a unit of length commonly used in physics, chemistry, and biology to measure very small distances, such as atomic and molecular scales. It is equal to 10⁻¹⁰ meters, or 0.1 nanometers (nm).
The unit is named after the Swedish physicist Anders Jonas Ångström, who made significant contributions to spectroscopy.
Key facts:
1 ångström = 10⁻¹⁰ meters = 0.1 nanometers
Used to measure atomic and molecular sizes, wavelengths of light, and crystal lattice constants
Common in fields like crystallography, chemistry, and materials science
Though largely replaced by the nanometer in the SI system, the ångström remains widely used in scientific literature to describe very small lengths.