The angstrom (or ångström) is a unit of length and is a non-SI but metric accepted unit with the symbol Å.
It is equal in length to one ten-billionth of a metre or 0.1 nanometres (0.1nm).
It is approximately the size of an atom and is mostly used to measure very small distances for example wavelengths of light.
The picometre is a unit of length and is a multiple of the SI unit metre. It uses the symbol pm.
It represents one trillionth of a metre, or one hundredth of an Ångström.
Because the picometre is so small, its use is restricted almost entirely to chemistry, quantum physics and particle physics. Atoms are typically 62 pm and 520 pm.
LISA (Laser Interferometer Space Antenna) is a probe planned for launch in 2034 to detect gravitational waves in space. Its measures these displacements with an accuracy of up to 20 pm over a distance of 2,500,000,000 m.