[magnetaress]

In 1868 astronomer Jules Janssen observed a solar eclipse in India through a prism. He noticed a bright yellow spectral line emanating from solar prominences – giant storms erupting from the Sun. The line was unidentified. At first it was thought to come from the chemical element sodium since it was close by to two other bright lines arising from this element. The two lines of sodium were known as the D1 and D2 Fraunhofer lines, named after their discoverer. The unknown line was identified later that year by astronomer Norman Lockyer in a solar spectrum and he named it the D3 Fraunhofer line. He concluded it was caused by a new, unknown element. Lockyer named it Helios, after the Greek word for the Sun. Helium was then unknown, and in fact was not discovered on the Earth for another 27 years, until 1895.

Several fascinating properties of helium have been discovered in the ensuing years. The alpha particle, produced through radioactive decay, was found to be a helium nucleus. It is the most basic product of nuclear fusion in stars, as protons are turned into helium nuclei. Helium, when cooled to near absolute zero, is a liquid and has no viscosity, a phenomenon we call superfluidity.

neet****

not suprising we started chasing nuclear stuff not long after [You must be logged in to view images. Log in or Register.]