This is COVID-19, and these are the bronchitis virus and some common cold viruses:
Whilst COVID-19 is often referred to as "coronavirus", in fact, all of these viruses are types of coronavirus. This is because they all share something in common: a halo of spikes surrounding their surface like a crown.
In 1968, the virologists that discovered this particular type of virus were reminded of something they'd seen before: the corona surrounding our Sun. So, the name "coronavirus" was chosen, in honour of the low density, super-heated, high-energy plasma surrounding our
star.
Whilst the COVID-19 spikes are just 25 billionths of a metre long, the Sun's corona extends 5 million miles above its surface. That's about 12 times the radius of the Sun itself!
Weirdly, the corona is hundreds of times hotter than the Sun's surface, despite it being further away from the core, where hydrogen is being fused to helium to generate our star's energy. Astrophysicists still aren't sure exactly what's causing this super-heating. It seems clear that the Sun's strong magnetic field is responsible in some way, but exactly how remains a mystery.
But this might not remain a mystery for much longer. Revolutionary new instruments like NASA's Solar Parker Probe (which is taking measurements of the Sun's corona from within it) might soon help to provide some answers...
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