An Animated Map of the Earth
July 8 2019 · Link to the Open-Source Code
This is one of the very few animated maps I made for my space cartography project! NASA publishes many Earth datasets at monthly time scales, and this GIF uses one frame per month to show the fluctuating seasons. The animation focuses mainly on data about Arctic sea ice and vegetation, but it was hard to choose - NASA has many other beautiful seasonal datasets, like fire, temperature, or rainfall.
The NASA Earth Observations website includes data on seasonal fire incidence (1), vegetation (2), solar insolation, or the amount of sunlight (3), cloud fraction (4), North Pole ice sheet coverage (5), and processed satellite images (6). My own map (7) combines the ice sheet data and the Blue Marble satellite images. The NEO database also has many more interesting datasets not shown here, like rainfall, chlorophyll concentration, or Carbon Monoxide.
To match the rest of the space map collection, I decided to emphasize the natural features of the Earth. So I didn’t include any country borders, country names, or other political information (though I did include large cities because I thought they counted as interesting physical features). Instead I tried to use colors and labels that emphasized the capes, oceans, deserts and forests of the world. I also used the bottom two corner maps to show the changes in cloud cover and temperature throughout the year.
In addition to data from NASA, I also used outlines and labels from Natural Earth. Natural Earth is a public domain map dataset with many useful features, and for this animation I used Natural Earth coastlines and labels for cities, ice sheets, lakes, and other large natural areas. I also used data from the USGS to map the Earth’s tectonic plates.
As an unrelated note, I’ve also gotten several emails asking for high-resolution digital wallpapers of my space maps - so here they are! These are completely free, and you can download the ZIP files of five different wallpapers for 4:3 resolution, 16:9, 16:10, and double monitors.
- Data: Blue Marble: Next Generation Topography and Bathymetry © 2004 NASA Earth Observations. Sea Ice Concentration and Snow Extent, Global (1 Day - SSM/I/DMSP) © 2017 NASA Earth Observations. Cloud Fraction (1 Month - AQUA/MODIS) © 2018 NASA Earth Observations. Solar Insolation (1 Month) © 2018 NASA Earth Observations. Earth True Color (1 Day - NPP/VIIRS) © 2019 NASA Earth Observations. Natural Earth 1:10m Cultural Vectors Populated Places © 2019 Natural Earth v4.1.0. Natural Earth 1:10m Physical Vectors River Centerlines © 2019 Natural Earth v4.1.0. Earth In Depth © 2019 NASA Science Solar System Exploration. Earth's Atmospheric Layers © 2010 USGS Spatial Services. Tectonic Plate Boundaries © 2019 . Reference texts: Astronomy, Andrew Fraknoi, David Morrison, Sidney C. Wolff et al. © 2016 OpenStax. Fonts: The labels on this map are typeset in Moon by Jack Harvatt. The title font is RedFlower by Type & Studio. Advice: Thank you to Chloe Pursey and Leah Willey for their helpful advice in making this map.
The Geology of Mars
June 24 2019 · Link to the Open-Source Code
This week’s map is an artistic rendition of the geologic map of Mars designed by the USGS. I used the same geology data as the original map, but I added more topographic and label data, redesigned the visual style, and also edited the key for a more general audience.
One of the most difficult parts of making this map was translating the key into plain English. The original USGS map was designed for geologists, so I had to look up almost all of the vocabulary. For example, my abbreviated definition for a caldera rim was “The rim of an empty magma chamber left behind after a volcanic eruption.” The original description was “Ovoid scarp, outlines single or multiple coalesced partial to fully enclosed depression(s); volcanic collapse, related to effusive and possibly explosive eruptions.”
In many cases my translated labels were approximate or less informative than the original, so I decided to also include the original acronyms for each type of geologic unit. These labels can be cross-referenced to the original data to learn more about each type of geologic formation in scientific terms.
Some of the distinctive geologic features on Mars. 1: Olympus Mons, the largest volcano in the Solar System. 2: Valles Marineris, a deep canyon system more than 4000km long. 3: Hellas Planitia, the largest visible impact crater in the Solar System. 4: Mars is divided geologically into the Northern lowlands (pale green) and Southern highlands (brown). Impact craters formed by colliding asteroids and comets (neon yellow) are scattered across the planet.
The individual layers used to make this map. 1-3: Geologic units, geologic contacts, and geologic features from the USGS dataset. 4-5: Hillshade and slope from a different USGS elevation dataset. 6: Nomenclature from NASA IAU. 7-8: Gridlines and a custom 3D effect designed in Photoshop.
I also spent a long time trying out different map projections for this design. I wanted to accurately show how much of the planet was made up of each geologic formation, so in the end I decided to use an Eckert IV equal-area projection. This type of map distorts object outlines, but it preserves the relative area of shapes across the globe. Eckert IV is not great for visualizing the polar regions, so I also added four inset maps to the corners to show each hemisphere of Mars (North, South, East, and West).
To map a 3D object in 2D space, the surface must be transformed using a map projection. There are many different projections, and for the maps in the Atlas of Space series I used Eckert IV, Orthographic, and Plate Carrée projections. To compare these different map projections, you can use a Tissot’s indicatrix - a set of circles of the same size plotted at different places on the globe. All map projections distort space, but you can see that the effects are quite different depending on the projection. 1: Plate Carrée. 2: Eckert IV. 3-5: Orthographic projections centered at different longitudes and latitudes.
- Data: Gazetteer of Planetary Nomenclature, International Astronomical Union (IAU). © 2019 Working Group for Planetary System Nomenclature (WGPSN). Planetary Symbology Mapping Guidelines, Federal Geographic Data Committee. Mars HRSC MOLA Blended DEM Global 200m v2. © 2018 NASA PDS and Derived Products Annex. USGS Astrogeology Science Center. Geologic Map of Mars SIM 3292. Kenneth L. Tanaka, James A. Skinner, Jr., James M. Dohm, Rossman P. Irwin, III, Eric J. Kolb, Corey M. Fortezzo, Thomas Platz, Gregory G. Michael, and Trent M. Hare. © 2014 USGS. Viking Global Color Mosaic 925m v1. © 2019 NASA PDS. Missions to Mars. © 2019 The Planetary Society. Reference texts: Astronomy, Andrew Fraknoi, David Morrison, Sidney C. Wolff et al. © 2016 OpenStax. Fonts: The labels on this map are typeset in Moon by Jack Harvatt. The title font is RedFlower by Type & Studio. Advice: Thank you to Henrik Hargitai, Oliver Fraser, Thomas Mohren, Chris Liu, Chloe Pursey, and Leah Willey for their helpful advice in making this map.
A Topographic Map of Mercury
June 17 2019 · Link to the Open-Source Code
This week’s blog post is a topographic map of the planet Mercury - the smallest planet and the one closest to the sun. I wanted to map each of the rocky planets in the same style, so this week’s code tutorial actually also includes code for mapping Mars, Venus, and the Moon.
Although Mercury has very few labeled features, I really liked the IAU naming theme for the planet. Craters on Mercury are named after famous artists - including some of my favorites, Lange (named for Dorothea Lange), Gaudí (Antoni Gaudí i Cornet), and Plath (Sylvia Plath).
For this collection of topographic maps, I also designed a cutaway diagram showing the interior layers of each planet. These figures were a little tricky to plot, because the layers on some planets were so thin that they were virtually invisible. To show even the thinnest layers, I designed an adjusted diagram where every layer has a minimum visible thickness:
In the diagram above, the left half shows the actual thickness of each layer, and the right half shows an adjusted version where each layer has a minimum thickness. For Mercury and the Moon there’s actually no difference, but the effect is much stronger for the other planets with a very thin crust or atmosphere. In the end I decided to use the adjusted graph for Earth, Mars, and Venus (with a disclaimer in the key that the figures were not to scale).
Each of the planet core diagrams also has a blurred image of the surface on the outside of the sphere. To make these I used stock images from Stellarium, an open-source planetarium software. I intentionally blurred these images in Photoshop, because a more detailed surface illustration would take the focus away from the cutaway core diagram layers.
The original Stellarium images shown alongside the finished cutaway diagrams for Venus, the Moon, Mercury, and Mars.
This project was a little heavier on the illustration side than my asteroid map last week. I had a lot of fun designing the scrollwork, and I also designed Photoshop overlays to add a 3D effect to the globes and the cutout core diagram. I’m working on a detailed illustration explanation to complement the code tutorial, so in a future blog post I’ll explain the design side of the project!
- Data: Gazetteer of Planetary Nomenclature, International Astronomical Union (IAU). © 2019 Working Group for Planetary System Nomenclature (WGPSN). Mercury In Depth. © 2019 NASA Science Solar System Exploration. Stellarium. © 2019 version 0.19.0. Mercury MESSENGER Global DEM 665m (64ppd) v2. © 2016 NASA PDS and Derived Products Annex. USGS Astrogeology Science Center. Reference texts: Astronomy, Andrew Fraknoi, David Morrison, Sidney C. Wolff et al. © 2016 OpenStax. Fonts: The labels on this map are typeset in Moon by Jack Harvatt. The title font is RedFlower by Type & Studio. Advice: Thank you to Oliver Fraser, Henrik Hargitai, Jennifer Hsiao, Chloe Pursey, and Leah Willey for their helpful advice in making this map.