For the 2017 solar eclipse, NASA published eclipse maps that took the irregular umbral shadow of the moon into account: the umbra is neither circular nor oval but irregular—more polygonal—thanks to the uneven topography and elevation of both the moon and the earth. Not accounting for that introduces errors into the map that could make the difference between observing a partial rather than a total eclipse. The process behind those more accurate eclipse maps, which involves computer processing of both lunar and terrestrial elevation models, has now been published in The Astrophysical Journal. [Bad Astronomy]

A study presented earlier this month at the Europlanet Science Congress maps the variations in Mars’s gravitational field.

Dr Root and colleagues from TU Delft and Utrecht University used tiny deviations in the orbits of satellites to investigate the gravity field of Mars and find clues about the planet’s internal mass distribution. This data was fed into models that use new observations from NASA’s Insight mission on the thickness and flexibility of the martian crust, as well as the dynamics of the planet’s mantle and deep interior, to create a global density map of Mars.

The density map shows that the northern polar features are approximately 300-400 kg/m³ denser than their surroundings. However, the study also revealed new insights into the structures underlying the huge volcanic region of Tharsis Rise, which includes the colossal volcano, Olympus Mons.

Abstract, press release, Universe Today.

Previously: New Gravity Map of Mars.

Last month the Chinese Academy of Sciences released a set of geologic maps of the moon at 1:2,500,000 scale—twice the resolution of the USGS’s 1:5,000,000 scale maps. Available, it seems, as a geologic atlas as well as quadrangle maps—though it’s not immediately apparent from where. News: Nature, Popular Science, Universe Today.

Looks like we’re not quite done with eclipse maps, especially the whimsical sort, and it’s not at all invalid for xckd to have (what is probably going to be) the last word on the subject (at least for a while), with this fictional map showing the fictional path of a fictional eclipse over a fictional landscape, with rueful descriptions of fictional places where trying to see the fictional eclipse will come to a bad end for the fictional observers. (And you thought it was bad you got clouds.)

Previously: Cloud Cover Risk During the 2024 Solar Eclipse; Mapping Two Solar Eclipses.

Eclipses aren’t any fun if you travel to go see one and it’s cloudy. I’ve been debating with myself what to do about next month’s total solar eclipse: the path of totality is a couple hours’ drive away and therefore manageable, but from what I’ve gathered the odds of clear skies aren’t great. These odds are based not on weather forecasts—still too early for that—but on historical data. For example, NASA Earth Observatory’s map, above, shows the average of the past 20 years of cloud cover across North America’s eclipse track on the day of the eclipse (April 8). Want more detail? Like, a lot more? See this incredibly detailed analysis from Eclipsophile’s Jay Anderson; I believe he’s a former meteorologist, and boy does it show in this piece. See also this Weather Underground article from last January, plus coverage from CBC News.

Previously: Mapping Two Solar Eclipses.

Alejandro Polanco’s latest Kickstarter project, Astronomy Atlas 1899, does for 19th-century astronomy atlases what his previous Geography 1880 project did for school atlases of the era: create an anthology of the best maps, drawings and diagrams from the books available to him.

In my library, in addition to the collection of geographical atlases from the 18th to the 21st century, there is a whole series of old books on astronomy, and of all of them, the ones that attract me the most are those published between 1880 and 1930. This was a time when science was developing at an astonishing rate and astronomy was changing radically. […]

In total there are twelve astronomical atlases in this library, mostly Spanish, French and English, published between 1880 and the early 1930s. From these I have selected the most interesting engravings and drawings, arranged them chronologically and given details of the original source. I have also supplemented many of them with other engravings from the Biblioteca Nacional de España and similar sources.

Digital (€18), softcover (€45) and limited-edition hardcover (€90) versions will be produced.

Two upcoming solar eclipses in North America—the annular eclipse on October 14, and the total eclipse on April 8, 2024—are the subject of numerous eclipse maps that track the path of totality and its duration along that path.

NASA’s Solar Eclipse Explorer currently focuses on this month’s annular eclipse, with paths of the 2017 and 2024 eclipse for comparison. [Maps Mania]

The Eclipse Company has separate maps for this month’s annular eclipse and next April’s total eclipse: these maps include data for locations along the path, including time, duration, the sun’s altitude and chance of clouds based on historical weather data. [PetaPixel]

The last time I went looking for eclipse maps, back in 2017, there was a website called GreatAmericanEclipse.com, which was the most recent of the websites showcasing the eclipse maps of Michael Zeiler. It’s still very much a going concern, with maps covering North America, individual U.S. states, and detailed maps of the path itself. These are static maps rather than the above interactive maps, but there are a lot of them, and not just for this month’s annular and next year’s total eclipse: there’s a fair bit of historical (and future!) eclipse maps there too.

Update 10:20 PM: Andy Woodruff’s scrolling map of the 2024 eclipse.

Previously: An Almost-Too-Late Roundup of Historical and Unusual Eclipse Maps; Mapping the August 2017 Solar Eclipse; Another Solar Eclipse Website; Michael Zeiler’s Solar Eclipse Map Website; Eclipse Maps.

On the LEGO Ideas website, user-submitted projects that reach the 10,000-supporter level are evaluated by LEGO to determine whether it can become a shipping product. Which is to say that Marc Sloan’s 2,360-piece “The Moon: Earth’s Companion,” a Moon map poster rendered in LEGO, stands at least some chance of being something one could buy at some point. [Universe Today]

The Global CTX Mosaic of Mars, produced by CalTech’s Bruce Murray Laboratory for Planetary Visualization, is a 5.7-terapixel mosaic of the Martian surface at a resolution of five metres per pixel. The mosaic is available in a number of different formats (via ArcGIS Online, KML, shapefiles), as well as via this online viewer; and the Lab is quite transparent about how they constructed it from Mars Reconnaissance Orbiter Context Camera (CTX) data. [Maps Mania/La Cartoteca]

You must see this. Ken Shirriff got his hands on an example of a navigational device from a Soyuz spacecraft and opened it up to see how it worked. Known as a Globus (its proper name is Индикатор Навигационный Космический—roughly, space navigation indicator), it’s an incredibly complicated marvel of gears and cams, an electromechanical analog computer that showed the capsule’s position on a physical globe. The position was predicted—the Globus received no navigational data. Ken’s got lots of photos of the innards at his website. See also his Mastodon thread. He has hopes of getting the thing operational, so keep an eye out for that.

(Based on the presence of NASA tracking sites on the globe, Ken thinks this particular unit was meant for the Apollo-Soyuz program, but I kind of wonder whether that was a function of the 1967 Rescue Agreement between the U.S. and the USSR instead.)

The Mercury capsule had something similar for a while: the Earth Path Indicator. One example sold for nearly $100,000 in 2019.

The USGS’s Astrogeology Science Center highlights three geologic maps of Mars released in late 2021. The maps are large-scale, focusing on specific Martian features (e.g. Olympus Mons, above).

Though maps have historically covered large areas, with crewed lunar missions on the horizon and other missions across the solar system in the planning stages, large-scale, small-area maps are starting to steal the limelight. These large-scale, small-area maps provide highly detailed views of the surface and allow scientists to investigate complex geologic relationships both on and beneath the surface. These types of maps are useful for both planning for and then conducting landed missions.

The maps are of Olympus Mons Caldera, Athabasca Valles and Aeolis Dorsa. Interactive versions, with toggleable layers over spacecraft imagery, are also available: Olympus Mons Caldera, Athabasca Valles, Aeolis Dorsa.

“A recently released set of topography maps provides new evidence for an ancient northern ocean on Mars. The maps offer the strongest case yet that the planet once experienced sea-level rise consistent with an extended warm and wet climate, not the harsh, frozen landscape that exists today.” Press release, video, article (JGR Planets). [Universe Today]

A new map of Mars reveals the abundance of aqueous minerals—clays and salts that form in the presence of water—that were created during the planet’s distant watery past. “The big surprise is the prevalence of these minerals. Ten years ago, planetary scientists knew of around 1000 outcrops on Mars. This made them interesting as geological oddities. However, the new map has reversed the situation, revealing hundreds of thousands of such areas in the oldest parts of the planet.”

Previously: Many Moon Maps; Can GPS Be Used on the Moon?

It turns out that the Geostationary Lightning Mapper (GLM) aboard the GOES-16 and GOES-17 earth observing satellites can do more than just detect lightning—it can also detect bolides, or very bright meteors, thanks to a new automatic detection algorithm. NASA Earth Observatory: “The map above shows the distribution of more than 3,000 bolides detected by the GLMs aboard GOES-16 and GOES-17 between July 2017 and January 2022. Blue points are bolides detected by GOES-16; pink points were detected by GOES-17. The lone pink point over the Atlantic Ocean was detected by GOES-17 during its commissioning phase before it was moved into its operational orbit over the West Coast.” (Bolides in the middle of the map are detected by both, and as you can see there’s a bit of parallax.)

VERITAS is one of two missions to Venus announced by NASA last week. Expected to launch between 2028 and 2030, VERITAS will produce an improved map of the Venusian surface with its two instruments: synthetic aperture radar to generate a high-resolution 3D topographic map, and a spectral emissions mapper to map rock types. News coverage: CNN, Global News, Slate, The Verge. Background from NASA; analysis from the Planetary Society.

A new study maps the possible locations of subsurface water-ice reservoirs, vital for any crewed missions. [Sky & Telescope]

Kenneth Field’s virtual globe of Mars follows in the footsteps of his 2016 map.

Interactive maps showing the locations and paths of the Curiosity and Perseverance rovers. [Maps Mania]

The Closest Stars is the latest astronomical map produced as part of Kevin Jardine’s long-running Galaxy Map project: it shows stars within 10 parsecs (32.6 light years) of our solar system. (Earlier maps covered much more territory: this map goes out to 6,000 pc.)

It’s fascinating, and has a lot of interesting information, but there’s a problem. Like all maps, it reduces three dimensions to a flat plane; as such it distorts the distance of stars that are substantially above or below the galactic plane but not very far away on the x or y axis. Take Beta Comae Berenices: it’s 9.18 pc away and as such should be at the edge of the map, but because it’s 9.18 pc away on the z axis, at nearly a right angle to the plane, it appears on the map as one of the closest stars. The distance above or below the plane is marked in parentheses, but that’s not enough: a label can’t compensate for a misleading position on the map. On the smaller-scale maps this isn’t as much of an issue, because the galaxy is more or less a disk or a lens, but within a 10-pc radius? This isn’t the right projection for the job.

I have a peculiar hobby of collecting Martian hypsometric tinting schemes: those sets of colors that cartographers use to depict elevations on the Red Planet. It’s a fascinating cartographic frontier. While the classic (and somewhat flawed) way of showing Earth’s elevations is to use a color scheme that starts with green lowlands, and then proceeds through some combination of brown/yellow/orange/red until it reaches white in the highest areas, there’s no standard yet for Mars. Maybe centuries from now, one of the schemes below will become that standard.

Huffman looks at fifteen schemes in total in the post, and in this video on YouTube:

Two geological maps of Venus have been published in Earth and Space Science. Produced by Vicki L. Hansen and Iván López, they each cover a 60-million-square-kilometre section of Earth’s twin: the Niobe Planitia Map Area geologic map (above, top) ranges from the equator to 57° north, and from 60° to 180° east longitude; the geologic map of the Aphrodite Map Area (above, bottom) is the Niobe Map Area’s southern hemisphere equivalent, covering the area from 60° to 180° east longitude, but from the equator to 57° south.

It’s important to remember a book’s target audience—its imagined ideal reader. In the case of Star Maps this is Kanas’s younger self, who came to map collecting via his lifelong interest in amateur astronomy. “I was frustrated that there was not a single book on celestial cartography that could inform me about the various aspects of my collecting,” he writes in the preface to the first edition. “What I needed was a book that not only was a primer for the collector but also had sufficient reference detail to allow me to identify and understand my maps. Nothing like this appeared, so I decided to write such a book some day” (p. xxi). In other words, for a compendium this is a surprisingly personal book, one that reflects his own journey into the subject and, presumably, his interests as a collector.

I’ll post the full review on The Map Room once I’ve checked my draft against the published copy. In the meantime, check out the issue of Calafia (PDF) in which it appears. (Update, 24 Jun 2020: Here it is.)

Star Maps: History, Artistry, and Cartography
3rd edition
by Nick Kanas
Springer Praxis, Sept 2019
Amazon (Canada, UK) | Apple Books | Bookshop

Cheung and Lee plotted the orbits of navigation satellites from the United States’s Global Positioning System and two of its counterparts, Europe’s Galileo and Russia’s GLONASS system—81 satellites in all. Most of them have directional antennas transmitting toward Earth’s surface, but their signals also radiate into space. Those signals, say the researchers, are strong enough to be read by spacecraft with fairly compact receivers near the moon. Cheung, Lee and their team calculated that a spacecraft in lunar orbit would be able to “see” between five and 13 satellites’ signals at any given time—enough to accurately determine its position in space to within 200 to 300 meters. In computer simulations, they were able to implement various methods for improving the accuracy substantially from there.

A mini-network of relays—a couple of satellites in lunar orbit, say—could improve accuracy further. [Geography Realm]

Previously: Many Moon Maps.

A new unified geologic map of the Moon, based on digital renovations that updated 1970s-era geologic maps to match more recent topographic and image data gathered by lunar orbiters, was released by the USGS last month. The map is “a seamless, globally consistent, 1:5,000,000-scale geologic map”; the paper version (25 MB JPEG) provides azimuthal projections beyond the 55th parallels and an equirectangular projection between the 57th parallels. [Geography Realm]

Previously: Lunar Geology and the Apollo Program.

Update, 22 April 2020: Version 2 of this map was released in March to address a number of errors in the first version.

The first global geologic map of Titan, based on radar and infrared data from the Cassini probe, has been released.

The map legend colors represent the broad types of geologic units found on Titan: plains (broad, relatively flat regions), labyrinth (tectonically disrupted regions often containing fluvial channels), hummocky (hilly, with some mountains), dunes (mostly linear dunes, produced by winds in Titan’s atmosphere), craters (formed by impacts) and lakes (regions now or previously filled with liquid methane or ethane). Titan is the only planetary body in our solar system other than Earth known to have stable liquid on its surface—methane and ethane.

The map is the result of research published today in Nature Astronomy.

Previously: Titan in Infrared; Mapping Titan with VIMS; A Topographic Map of Titan.

A team of researchers led by University of Hawaii astronomer Brent Tully has mapped the structure of the universe at a vast scale. In particular, they have mapped the shape of the Local Void, an empty expanse of intergalactic space hundreds of millions of light years across; the Milky Way is found at the edge of the Void. From the University of Hawaii’s Institute for Astronomy press release:

Now, Tully and his team have measured the motions of 18,000 galaxies in the Cosmicflows-3 compendium of galaxy distances, constructing a cosmographic map that highlights the boundary between the collection of matter and the absence of matter that defines the edge of the Local Void. They used the same technique in 2014 to identify the full extent of our home supercluster of over one hundred thousand galaxies, giving it the name Laniakea, meaning “immense heaven” in Hawaiian.

A video map and interactive 3D model are available. The study behind this model was published in The Astrophysical Journal (paywall). [NBC News]

Previously: Lunar Cartography During the Age of Apollo; Many Moon Maps; Lunar Geology and the Apollo Program.

Planetary geologist David Rothery writes about the early attempts to map the Moon’s geology, both before and after the Apollo program. There was a symbiotic relationship between the map and the mission: maps suggested where landings might be most profitable from a geological perspective; and field work by the astronauts informed later moon maps.