The intermediate range order of covalent glasses has been extensively studied in terms of the first sharp diffraction peak (FSDP), but the direct observation of the atomic density fluctuations that give rise to FSDP is still lacking. Addressing this gap, researchers employed a new energy-filtered angstrom-beam electron diffraction technique to provide the direct experimental observation for the origin of FSDP in silica glass, providing important insights into the atomic structure of glasses.