The coronavirus is a roughly spherical particle studded with club-shaped spikes that radiate outward, giving it the appearance of a crown. This crown-like look is the reason for its name: “corona” comes directly from the Latin word for crown. The virus is incredibly small, about 100 nanometers across, meaning you’d need to line up roughly 1,000 of them to span the width of a human hair. You can’t see it with a regular microscope. Everything we know about its appearance comes from powerful electron microscopes and the colorized images scientists create from those photographs.
The Crown of Spikes
The most recognizable feature of any coronavirus is the layer of projections covering its outer surface. In 1967, virologist June Almeida first described these projections on a common cold coronavirus: each spike sits on a narrow stalk and has a bulbous head roughly 10 nanometers across, with the full spike extending about 20 nanometers from the surface. Under an electron microscope, these club-shaped spikes look like the points of a crown, or like the glowing halo around the sun during a solar eclipse (which is also called a corona).
On SARS-CoV-2, the virus behind COVID-19, each spike is actually a cluster of three identical protein chains twisted together into a structure about 16 nanometers tall. The upper portion fans out into a V shape that gives the spike its bulky, triangular head. The lower portion forms a narrower stalk that anchors into the virus’s outer shell. These spikes aren’t just decoration. They’re the tools the virus uses to latch onto human cells, and they’re the target of most COVID vaccines.
The Outer Shell
Beneath the spikes, the coronavirus is wrapped in a lipid bilayer, essentially a thin bubble of fat stolen from the human cell it last replicated in. This fatty envelope is fragile, which is why soap and alcohol-based hand sanitizers destroy the virus so effectively. They dissolve that outer layer.
Embedded in this fatty shell are two other proteins besides the spike. The most abundant is the membrane protein, which helps give the virus its shape and structural integrity. A smaller envelope protein forms tiny channels in the membrane that play a role in viral assembly. Together, these proteins create the smooth, rounded surface visible between the spikes in microscope images.
What’s Inside
Inside that outer shell, the virus carries a single long strand of RNA, its genetic blueprint. This strand is about 30,000 genetic letters long, making it one of the largest genomes among RNA viruses. It doesn’t just float loosely inside the particle. A packaging protein called the nucleocapsid wraps around the RNA, organizing it into roughly 38 compact bundles per virus particle. These bundles form when pairs of nucleocapsid proteins latch onto specific looped structures in the RNA, then link together into larger clusters of about six pairs each. The result is a tightly wound interior that protects the genetic material and helps it unpack efficiently once the virus enters a new cell.
Why the Famous Images Are Colorized
If you’ve seen images of the coronavirus online, you’ve almost certainly seen a version with vivid colors: bright red or orange spikes on a gray sphere, or glowing yellow particles against a blue cell background. These colors aren’t real. Electron microscopes, the only instruments powerful enough to photograph individual virus particles, produce images in black and white. They work by bouncing beams of electrons off a sample rather than using visible light, so there’s no color information to capture.
The striking images released by institutions like the National Institute of Allergy and Infectious Diseases are carefully hand-colored by visual specialists. An artist studies the raw black-and-white photograph, adjusts the contrast, then zooms in and selects individual virus particles and cell structures by hand. Colors are chosen for clarity and contrast, making it easy for non-experts to distinguish the virus from surrounding cells. The artist also considers aesthetics, experimenting with color combinations that are visually distinctive. The result is scientifically accurate in terms of shape and structure, but the palette is an artistic choice designed to make the image informative and accessible.
Do Variants Look Different?
Variants like Delta and Omicron carry dozens of mutations, mostly in the spike protein, but these changes are far too small to see even under an electron microscope. The differences are molecular, not visual. An Omicron particle looks essentially identical to the original strain at the level of microscope imaging.
At the molecular level, though, structural biologists have mapped real differences using techniques that can resolve individual atoms. The Omicron spike, for example, has tighter packing between the three spike protein chains, with its upper receptor-binding regions locking together more firmly in a closed, downward-facing position. This is a subtle shift in how the spike holds itself before it contacts a human cell. The Omicron spike also shows increased flexibility at the region responsible for fusing with cell membranes, which may relate to how the variant enters cells differently. But none of these changes alter the virus’s overall look. Every SARS-CoV-2 variant still appears as the same crowned sphere that gave coronaviruses their name over 50 years ago.