Walter Robert Wilhelm Grotrian (April 21, 1890 in Aachen

Aachen

Aachen has historically been a spa town in North Rhine-Westphalia, Germany. Aachen was a favoured residence of Charlemagne, and the place of coronation of the Kings of Germany. Geographically, Aachen is the westernmost town of Germany, located along its borders with Belgium and the Netherlands, ...

; † March 3, 1954 in Potsdam

Potsdam

Potsdam is the capital city of the German federal state of Brandenburg and part of the Berlin/Brandenburg Metropolitan Region. It is situated on the River Havel, southwest of Berlin city centre....

) was a German

Germany

Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

 astronomer

Astronomer

An astronomer is a scientist who studies celestial bodies such as planets, stars and galaxies.Historically, astronomy was more concerned with the classification and description of phenomena in the sky, while astrophysics attempted to explain these phenomena and the differences between them using...

 and astrophysicist.

Grotrian studied the emission

Emission (radiocommunications)

Emission is the radiation or radio signal produced or emitted by a radio transmitting station....

 line from the solar corona in the green

Green

Green is a color, the perception of which is evoked by light having a spectrum dominated by energy with a wavelength of roughly 520–570 nanometres. In the subtractive color system, it is not a primary color, but is created out of a mixture of yellow and blue, or yellow and cyan; it is considered...

 region of the spectrum

Spectrum

A spectrum is a condition that is not limited to a specific set of values but can vary infinitely within a continuum. The word saw its first scientific use within the field of optics to describe the rainbow of colors in visible light when separated using a prism; it has since been applied by...

; this emission line could not be attributed to any known chemical element

Chemical element

A chemical element is a pure chemical substance consisting of one type of atom distinguished by its atomic number, which is the number of protons in its nucleus. Familiar examples of elements include carbon, oxygen, aluminum, iron, copper, gold, mercury, and lead.As of November 2011, 118 elements...

 and was thought to be a new element (which scientists named "coronium

Coronium

Coronium was the name of a suggested chemical element, hypothesised in the 19th century. It was named after the solar corona.During the total solar eclipse of 7 August 1869, a green emission line of wavelength 530.3 nm was observed in the coronal spectrum...

"). Grotrian and Bengt Edlén

Bengt Edlén

Bengt Edlén was a Swedish professor of physics and astronomer who specialized in spectroscopy. He participated in solving the Corona Mystery: unidentified spectral lines in the sun's spectrum were speculatively believed to originate from a hitherto unidentified chemical element termed coronium...

 from Sweden

Sweden

Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....

 demonstrated that the two observed emission lines arise from iron

Iron

Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...

 atom

Atom

The atom is a basic unit of matter that consists of a dense central nucleus surrounded by a cloud of negatively charged electrons. The atomic nucleus contains a mix of positively charged protons and electrically neutral neutrons...

s that have lost about half their 26 electrons.http://www.eso.org/outreach/press-rel/pr-2001/pr-17-01.html

Named after Grotrian

• The impact crater Grotrian
  Grotrian (crater)
  Grotrian is a lunar impact crater that is located on the southern hemisphere on the far side of the Moon. It lies to the north of the huge walled plain Schrödinger, within the radius of that formation's outer blanket of ejecta...
  
   on the Moon
  Moon
  The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...
  
  
• The Grotrian diagram
  Grotrian diagram
  A Grotrian diagram or term diagram shows the allowed transitions between the energy levels of atoms. They can be used for one electron and multi electron atoms. They take into account the specific selection rules related to changes in angular momentum of the electron. The diagrams are named after...
  
   in atomic spectroscopy showing the allowed transitions between atomic energy levels
• Character in "Time Keeps on Slippin'" episode of Futurama
  Futurama
  Futurama is an American animated science fiction sitcom created by Matt Groening and developed by Groening and David X. Cohen for the Fox Broadcasting Company. The series follows the adventures of a late 20th-century New York City pizza delivery boy, Philip J...