365DaysDate: March 25, 2009


Title: Selenography: Naming and Mapping the Moon

Podcaster: Mark Tillotson, amateur astronomer, lunar enthusiast, author of Today in Astronomy blog, member of the Lehigh Valley Amateur Astronomical Society and IYA_US team member.

Links: Today in Astronomy:
Lunar Mark:
The Astronomy Compendium:

Description: It all started with the second person who created a lunar map. Naming features on the Moon has had a long and contentious history. The various lunar maps, sketches and images produced during the last four centuries show how difficult it can be to be accurate and consistent in lunar nomenclature. Amateur astronomer ‘Lunar Mark’ Tillotson talks about some of the major selenographers and the people who are honored with a lunar feature.

Bio: Mark Tillotson is an engineer and amateur astronomer living in Pennsylvania. He is interested in the Moon, the history of astronomy and science in general. Mark is the author of two blogs, Today in Astronomy and Lunar Mark, and created the Astronomy Compendium; a wiki-spaces site designed as a collection of information about the people, places and events that shaped the science of Astronomy into the form we know today. He is the Star Party coordinator at the Lehigh Valley Amateur Astronomical Society and a communications team member for IYA2009 US; posting updates on Facebook as IYA Cosmos and on Twitter as IYA_US.

Today’s Sponsor: This episode of “365 Days of Astronomy” is sponsored by AstronomyCast.

Lunar nomenclature has been a mess since the second person to create a lunar map did not use the same names as the first person.

And this problem continues to this day.

Music clip: Fly Me to the Moon, Frank Sinatra

Hi! This is Lunar Mark. I am an amateur astronomer and a self-professed Lunatic from eastern Pennsylvania. Welcome to the 365 Days of Astronomy podcast. I am here to talk to you about Selenography: Naming and Mapping the Moon.

+Selenography defined – An Outline of Conflicts
Selenography is the study of the surface and physical features of the Moon. It comes from the word Selenology, which refers to the study of the Moon or lunar science in general. The word selenology is derived from Selene, the Greek lunar deity. The primary focus of selenographers is the mapping and naming of the lunar maria, craters, mountain ranges, and other various features. This job was given a tremendous boost by the images of the near and far sides of the Moon obtained by orbiting spacecraft during the early space era. Yet even today some regions of the Moon remain poorly imaged (especially near the poles) and the exact locations of many features are uncertain by several kilometers.

Despite the strong influence ascribed to the Moon throughout history there are virtually no features that had been individually named prior to the invention of the telescope. Since then, there have been several rounds in the ongoing struggle to name and map the Moon.

In the middle of the seventeenth century, for example, one selenographer claimed to be the first person to come up with the idea of naming lunar features even though a map with 325 names had been published two years earlier!

Lunar nomenclature became a hot issue (again) in the sixties with the start of the space age and involved astronomers, geophysicists, astro-geologists, planetary cartographers, the Board of Geographical Names, national and international committees and included an enormous number of back-and-forth letters, meetings, arguments, vendettas, shady politics and personal grudges.

Today the International Astronomical Union is the official body that determines the nomenclature schemes and individual names on planetary bodies, including the Moon. There are over 2,200 named features on the Moon and if you go to The-Moon Wiki, which is linked in the show notes, you can find an individual page for each feature. How cool is that?

+Ancient nomenclature – Caspian and Crisium
Since prehistoric times mankind has looked into the skies and seen all kinds of fanciful shapes and images in the groupings of the stars. The Moon was also subjected to this type of pareidolia using the shadings of light and dark areas, especially when the Moon is at or near full. The image I was taught as a kid was of the ‘Man in the Moon.’ But there have been many others, including an old man with a bundle of sticks, an old lady spinning, two children carrying a bucket (Jack and Jill, perhaps?), a dragon and a tree and a large variety of rabbits.

‘The Capsian’ seems to be one of the only names for a specific feature to have come from ancient times. It refers to what is now known as Mare Crisium – the Sea of Crises.

Perhaps the best lunar map from the pre-telescopic era was created by William Gilbert in about 1600. It is a pen-and-ink sketch that includes a few names for some of the broad areas visible from Earth. It is interesting to note that Gilbert used the reverse of the current convention: he named the dark areas as land forms and the light areas as seas. He also noted that “no images of the Moon’s face had come down from antiquity, preventing the possibility of detecting any major changes in the markings.”

+Harriot / Galileo: The Telescopic Era Begins
The International Year of Astronomy is celebrating the 400th anniversary of Galileo pointing his telescope at the night sky. One of the objects that he looked at was the Moon and he made a number of sketches that are well known today. If you recall, however, his sketches do not have any names. He simply drew the major visible features. There has also been a lot of discussion of Thomas Harriot, the English Astronomer, who in 1611 created the first ‘telescopic’ map of the Moon. Harriot did indeed view the Moon 4 months prior to Galileo and he made a 6-inch diameter, pen-and-ink drawing of the full Moon with a simple form of nomenclature. The reason Harriot did not have the lasting scientific impact that Galileo did is that Harriot’s map was not well known until it was published in 1965!

+The Big 3: Langrenus, Hevelius and Riccioli, 1651
Most people are familiar with the major figures in astronomy; Galileo, Nicholas Copernicus, Johannes Kepler, Isaac Newton and Phil Plait. But the original ‘Big 3’ in lunar mapping were Van Langren, Hevelius and Giovanni Riccioli.

The first real map of the Moon was published by Van Langren in 1645. It depicts the topography of the Moon and surface shadings. He also introduced the basic naming scheme that is still used today. Hevelius published a full-Moon image in 1647 that is fairly accurate and also depicts the additional areas of the Moon that are visible due to the libration, or wobble, of the Moon.

Giovanni Riccioli, an Italian Jesuit, created a lunar map in 1651 that listed many of the names that are still in use today. He named the most prominent craters after famous scholars, such as Tycho, Copernicus and Ptolemy. Mountain ranges are named after mountain ranges here on Earth.

+The New Standard: Beer & Mädler, 1837
The next major highlight came in 1837 with the publication of Mappa Selenographica by Beer and Mädler. This was the primary standard in lunar maps for many years. It was a both an improvement over earlier maps and a combination of styles and techniques.

+The IAU Takes Charge
As the 20th Century dawned there were many advances in telescopic design and the need for standardization in nomenclature of both the Moon and other planetary bodies. The IAU took over responsibility for a universal system of nomenclature and a comprehensive view of the HYPERLINK “” l “toc0” changes and additions by the IAU can be found on the-Moon Wiki.

+The Current Standard: Rükl
The current standard in lunar mapping is the Atlas of the Moon by Antonin Rükl, published in 1990 by Sky Publishing. I finally managed to get a copy of this out-of-print book and it will be a constant companion whether I’m at the telescope or not!

All along the twisting road from 1609 to today there have been many contributions to the art and science of naming and mapping the Moon. They are far too numerous to cover them all in this podcast but I have linked to a great HYPERLINK “” timeline of lunar mapmaking on LPOD. Following this road can be almost as much fun as finding the actual craters on the Moon!

+Creating a Lunatic
I would like to take a moment to thank Chuck Wood, the creator of LPOD, the Lunar Photo of the Day and the-Moon Wiki. I became interested in astronomy again about 3 years ago when I was invited to a Star Party at the local astronomy club, the Lehigh Valley Amateur Astronomical Society, by my friend Simon Porter. I realized right away that I was fascinated with looking at the Moon through a telescope. As part of trying to learn more I began visiting LPOD every day. Chuck announced that he was starting the new wiki-style web site as a way to collect all things lunar and he was asking for help. I immediately volunteered and a lunatic was born! The Moon Wiki has grown into one of the largest single repositories of lunar information on the web. There has been input from a variety of people and information and links continue to be added every day. Check out this fantastic site – but beware! You may become a lunatic, too!

My love of both astronomy and history has combined in the form the ‘Today in Astronomy’ blog, where I help celebrate the International Year of Astronomy. Each day I highlight an astronomer or event from that day in the history of astronomy. You can find it at todayinastronomy dot blogspot dot com or check the show notes at 365 Days of Astronomy dot org. While there you can also find links to the LunarMark blog, The Astronomy Compendium, and some more of my favorite web sites.

I would also like to note that the main resource for today’s podcast is Ewen Whitaker’s fabulous book, Mapping and Naming the Moon: A History of Lunar Cartography and Nomenclature.

Thanks for listening and remember to invite a friend to look up at the night sky!

This is Lunar Mark signing off from the Moon!

365 Days of Astronomy
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