Prior to its discovery on earth helium's existence was confirmed in the sun. How was this possible?

Answer 1

Astronomers (and chemists) had discovered that specific elements and molecules emitted very specific frequencies of light when heated. The frequencies have to do with the energy level differences in the orbits of electrons.

For example, see the Balmer series for the specific lines of emission for electrons dropping to level 2 in hydrogen.

Spectral lines were analyzed and identified. After eliminating all the ones that were known, they were left with some that were not explained.

From the frequencies, they found the energy levels of the electron orbits, this gave them an idea of the number of electrons and the charge on the nucleus). Because the numbers were small enough, they quickly identified the atom as having 2 protons (and 2 electrons in its neutral state).

They called it helium (from Helios, the classical Greek god representing the Sun).

Answer 2

Since helium is so inert, it doesn't react with anything. So scientists had no idea the element even existed at the time (helium was discovered in 1868, the periodic table of the elements wasn't even proposed until 1869).

But spectrographic analysis of the sun was an important study, and it wasn't clear at that time if there might be elements on the sun that didn't exist anywhere else. So a new element found in the sun's spectrum was no surprise, no big deal at the time (the word "helium" comes from the Greek "helios", meaning sun).

Answer 3

spectrometer.
you aim a spectrometer at anything either emitting or passing light, and the resulting wavelengths will tell you what sort of materials it is passing through or emitting from

Answer 4

Yup, light spectrometer