
right|thumb|A solar eclipse, with the solar corona visible. Coronium was the name of a suggested chemical element, hypothesised in the 19th century. The name, inspired by the solar corona, was given by Gruenwald in 1887. A new atomic thin green line in the solar corona was then considered to be emitted by a new element unlike anything else seen under laboratory conditions. It was later determined to be emitted by iron (Fe13+), so highly ionized that it was at that time impossible to produce in a laboratory.
right|thumb|A solar eclipse, with the solar corona visible. Coronium was the name of a suggested chemical element, hypothesised in the 19th century. The name, inspired by the solar corona, was given by Gruenwald in 1887. A new atomic thin green line in the solar corona was then considered to be emitted by a new element unlike anything else seen under laboratory conditions. It was later determined to be emitted by iron (Fe13+), so highly ionized that it was at that time impossible to produce in a laboratory.
== Solar spectroscopy == During the total solar eclipse of 7 August 1869, a green emission line of wavelength 530.3 nm was independently observed by Charles Augustus Young (1834–1908) and William Harkness (1837–1903) in the coronal spectrum. Since this line did not correspond to that of any known material, it was proposed that it was due to an unknown element, provisionally named coronium.
Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).