New Gravity Map of Mars

NASA/Goddard/UMBC/MIT/E. Mazarico

A new gravity map of Mars that shows the thickness of the Martian crust based on gravity measurements from Martian orbiters, reveals a crust that is less dense and shows less variation than earlier maps. “The researchers mapped the density of the Martian crust, estimating the average density is 2,582 kilograms per meter cubed (about 161 pounds per cubic foot). That’s comparable to the average density of the lunar crust. Typically, Mars’ crust has been considered at least as dense as Earth’s oceanic crust, which is about 2,900 kilograms per meter cubed (about 181 pounds per cubic foot).”

An Almost-Too-Late Roundup of Historical and Unusual Eclipse Maps

I meant to post this before today’s solar eclipse, but I spent a good chunk of the past few days dealing with basic site maintenance; during the eclipse itself I was, well, observing and photographing it. But while the iron may not be as red-hot as it was even eight hours ago, it’s still glowing a bit, so how about I clear out some bookmarks:

Eclipse maps that pinpoint the zone of totality date back to the eighteenth century. Atlas Obscura looks at those early eclipse maps, notably those from Edmond Halley.

In the runup to the eclipse there have been some seriously weird and quirky eclipse maps, many of which correlating the path of the eclipse to utterly unrelated things. The first one I saw was this one: the path of the eclipse versus bigfoot sightings.

There have been others. Many others, to the point of absurdity. Maps on the Web has been collecting these maps over the past few weeks, and All Over the Map’s roundup of eclipse maps features them as well.

Earlier this month, the Washington Post’s Wonkblog noted the eerie correlation between Google searches about the eclipse and the path of the eclipse itself:

Washington Post

Finally, people were watching traffic maps to track the number of people travelling to watch the eclipse. Apparently eclipse-related traffic congestion was a thing. (Here’s Michael Zeiler’s forecast, based on population statistics.)

Mapping the August 2017 Solar Eclipse

Drive times to the centerline of the August 21, 2017 total solar eclipse
Michael Zeiler,

Eclipse maps—maps that show the path of solar eclipses across the surface of the Earth—are very much a thing. As I wrote in my first blog post about eclipse maps back in 2010, “These maps are vital to eclipse chasers, who spend vast sums travelling to places where they can see one, and those slightly less insane who nevertheless are interested in when the next one comes around.” Eclipse chasers are already getting ready for next month’s solar eclipse, which transects the continental United States on 21 August, and of course there are lots of maps.

Michael Zeiler, whose website about solar eclipse maps, coincidentally called, I told you about in 2011, has launched a separate website dedicated to next month’s eclipse, called (wait for it)  There are eclipse maps for every state the path passes through, various maps presenting additional information, and a 10-foot-long strip map of the path of totality.

But knowing an eclipse’s path isn’t always enough. There’s nothing worse than spending a fortune to get to an eclipse-viewing spot only to discover it’s clouded over. You can’t predict the skies far enough in advance, but you can factor in the likelihood that skies will be clear or cloudy for a given location, based on historical weather data. That’s what NOAA’s eclipse cloudiness maps do. [GeoLounge]

Eleanor Lutz’s Goddesses of Venus

Last year Eleanor Lutz published a medieval map of Mars that, while not strictly medieval in style, was a magnificent application of an ostensibly old aesthetic to a very modern map subject. Now she’s produced a sequel: The Goddesses of Venus is an annotated map that explores the etymological origins of each of Venus’s features, nearly all of which are named after women or female mythological figures. [Kottke]

Previously: ‘Here There Be Robots’: Eleanor Lutz’s Map of Mars.

The Last Unmapped Places

Lois Parshley’s essay on the last unmapped, mysterious places—Greenlandic fjords, the slums of Haiti, the ocean’s depths, black holes in space—is a long read worth reading. Originally published last month as “Here Be Dragons: Finding the Blank Spaces in a Well-Mapped World” in the Virginia Quarterly Review, it’s been reprinted by the Guardian, in an edited, tighter version, as “Faultlines, Black Holes and Glaciers: Mapping Uncharted Territories.”

Pluto Globe Announced

pluto-globeAstronomy magazine has announced a new globe of Pluto based on data from the 2015 flyby of the dwarf planet by the New Horizons probe. The 12-inch globe is limited by what New Horizons was able to see: it’s low-resolution in some areas and blank in others. In addition, 65 surface features are labelled—a brave move considering that all the names are provisional until the IAU approves them. The globe sells for $100.

Gaia’s First Sky Map


Yesterday the European Space Agency released a sky map based on the first 14 months of data collected by the Gaia spacecraft, an astrometric observatory whose mission is to create a precise catalogue of astronomical objects’ position and relative motion. Several versions are available: annotated, unannotated, annotated with titles (above), unannotated with titles. The maps contain artifacts (curves and stripes) from Gaia’s scanning procedures, but they’ll improve as more data is added over the course of Gaia’s five-year mission.

A Globe of Percival Lowell’s Mars


Hand-made globes are increasingly a thing, apparently. As Atlas Obscura reports this week, Michael Plichta’s company, Planetenkugel-Manufaktur, is producing a hand-crafted globe of Mars with a twist: it’s based on Percival Lowell’s maps, which (erroneously) showed the Martian surface covered in canals. It’s delightfully retro and I love it. Here’s a video:

Nowhere on the website is a price mentioned, which tells me that I won’t be able to afford one, damn it.

New Atlas of Artificial Sky Brightness


A new online atlas of artificial sky brightness is now available, based on updated light pollution data published last week. (There’s also a 3D globe version that may not work in all browsers.) Light pollution, as I’ve blogged before, is the bane of professional and amateur astronomers alike, obscuring fainter objects and interfering with observations, both naked-eye and through telescopes. As the article in Science Advances puts it, “This atlas shows that more than 80% of the world and more than 99% of the U.S. and European populations live under light-polluted skies. The Milky Way is hidden from more than one-third of humanity, including 60% of Europeans and nearly 80% of North Americans.” [Rumsey Map Center]

Previously: Light Pollution Maps; Testing Light Pollution Maps; Testing Light Pollution Maps Redux; Darker Than You Think.

An Ordnance Survey Roundup


  • Concomitant with the Survey’s map of Mars was a competition to design a map symbol to represent landing sites. The winner has been announced: the OS will use Paul Marsh’s symbol, which incorporates the Mars symbol with landing gear, on its Mars maps in the future.

Map Contest: Proposed Mars Landing Sites

The ICA’s Commission on Planetary Cartography has put out a call for maps of the 47 proposed exploration zones on Mars.

The project is to select one candidate landing site and design an actual map that you envision will be useful in surface operations. We ask that you do not create simply a geologic map, but rather a product that can be used by the astronauts during their approximately one-year long mission within the Exploration Zone. This requires creativity, and it is also useful to have a good knowledge of surface features, surface hazards, science goals and the use of the proper cartographic tools.

The contest is open to students, young professional cartographers, and graphic artists in any country of the world.

More at the ICA and All Over the Map. [Leventhal/WMS]

The Nuns Who Helped Map the Night Sky

Catholic News Service: “Of the many momentous or menial tasks women religious perform, one of the better-kept secrets has been the role of four Sisters of the Holy Child Mary who were part of a global effort to make a complete map and catalog of the starry skies. […] Sisters Emilia Ponzoni, Regina Colombo, Concetta Finardi and Luigia Panceri, all born in the late 1800s and from the northern Lombardy region near Milan, helped map and catalog nearly half a million stars for the Vatican’s part in an international survey of the night sky.” [@CUATheoPhilLib]

The First Global Topographic Map of Mercury


The first complete topographic map of Mercury, based on data from the MESSENGER mission, was released last Friday: MESSENGER, USGS. The version above is a Robinson projection without labels (Robinson with labels, global DEM). “Mercury’s surface is colored according the topography of the surface, with regions with higher elevations colored brown, yellow and red, and regions with lower elevations appearing blue and purple.” [GIS and Science, The National Map]