One hundred years ago this coming Monday, the International Astronomical Union was founded as an association of professional astronomers to act as the sole authority on naming celestial bodies and their visible features.

Prior to the IAU, astronomical naming was haphazard, with no universal agreement on how to name newly discovered heavenly bodies, or even the constellations themselves. Constellations were either prominent star patterns identified by the ancient Greeks separated by nebulous boundaries, or groupings of faint stars created by astronomers looking to secure a place in history as late as the 1880s.

In 1922, using a list of 88 constellations suggested by American astronomer Henry Norris Russell, the IAU tasked Belgian asteroid and comet hunter Eugene Delporte with devising imaginary boundaries for each of them, which are still in use today.

The IAU has also established naming rules for planetary features: craters on Mercury commemorate writers, poets, artists, and composers; Venus’s volcanic domes are named after fertility goddesses from various cultures; and Mars’s largest craters honor deceased scientists (especially those who studied the Red Planet).

Since the IAU is the sole authority on astronomical naming, those who have paid to “name a star” will be disappointed to learn that such names are not officially recognized by the IAU, and will thus not be used to reference them by astronomical researchers.

The IAU became the center of controversy in 2006 with Pluto’s “demotion” from planet to dwarf planet. Their somewhat arcane definition of “planet” has been criticized by some, and may well be revised by the IAU in the future (given that it currently only applies to bodies within the Solar System). So, if Pluto ever regains its planetary status, it will be the IAU which confers it.(tncms-inline)c2aee444-9e58-487a-a77a-3b62125dae0f[0](/tncms-inline)

Next column: Mercury’s best morning appearance of the year.

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Chris Anderson manages the College of Southern Idaho’s Centennial Observatory in Twin Falls. He can be reached at 732-6663 or canderson@csi.edu.


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