Which Belgian astronomer drew the official boundaries of the 88 modern constellations, published in 1930? The astronomer was Eugène Joseph Delporte.
Delporte was a Belgian astronomer associated with the Royal Observatory of Belgium. Working for the International Astronomical Union, he transformed constellations from loosely defined star patterns into precisely mapped regions covering the entire celestial sphere.
His boundaries were drawn along lines of right ascension and declination, celestial equivalents of longitude and latitude. The IAU approved the boundaries in 1928, and Delporte’s work was published in 1930 in Délimitation scientifique des constellations, together with an accompanying celestial atlas.
The other choices made important contributions to astronomy but did different work. Johann Bayer produced the influential Uranometria star atlas, Nicolas-Louis de Lacaille introduced southern constellations, and Johannes Hevelius created several northern constellations. Delporte’s achievement was standardizing where each official constellation begins and ends.