Real Planets

Tap a spot to zoom in and name the place; tap again to go out. Play flies to Everest.

The real Earth from NASA and NOAA maps: colors from NASA's Blue Marble (a cloud-free mosaic from the Terra satellite), heights from NOAA's ETOPO 2022, and city lights from NASA's Black Marble. The oceans lie flat at sea level. Each splat sits at its height and leans with its ground, so the sun lights the slopes facing it.

The relief is exaggerated twenty times by default (Everest, 8.8 km high, is less than a thousandth of Earth's width); pick True height in the Splash tab to see it as it is. Earth turns once every 23 hours 56 minutes; here an hour passes each second. There are no clouds or shadows. A tap zooms in and names the place from Natural Earth's maps; tap again to go out.

Earth drawn from real maps: every splat sits at its place's measured height and has its place's measured color, and each named feature is where the planetary gazetteer puts it. The relief, the turning speed and the lighting are simplified, and each simplification is labeled in the splash.

1. Correct

   The color map is Blue Marble: Next Generation (July 2004).¹

   tools/sp2-maps.mjs reads the source file named in src/space/worlds.js and averages it into the splash's smaller maps (east longitudes from -180° to 180°).

2. Correct

   The elevation map is ETOPO 2022 Global Relief Model (60 and 15 arc-seconds).²

   tools/sp2-maps.mjs reads the source file named in src/space/worlds.js and averages it into the splash's smaller maps (east longitudes from -180° to 180°).

3. Correct

   The lights at night is Black Marble 2016 (Earth at Night).³

   tools/sp2-maps.mjs reads the source file named in src/space/worlds.js and averages it into the splash's smaller maps (east longitudes from -180° to 180°).

4. Correct

   Earth turns once every 23.9345 hours (its sidereal day), sped up by the chosen factor.⁴

   Each frame the drive adds the elapsed time times the speed-up, over the day's length, to the turn.

5. Correct

   A tap flies to Mount Everest and the Himalayas at 27.988°, 86.925° east, and the map shows it there. Its summit on the map is over 8,000 m, within 15 km (ETOPO's 15-arc-second cells, about 450 m, average the very top).⁵

   The drive turns the feature's direction to face the viewer and glides the camera to it; the test checks the turn and the map's heights round the listed center.

6. Correct

   A tap flies to The Grand Canyon (at Phantom Ranch, on the canyon floor) at 36.106°, -112.095° east, and the map shows it there. On the map, the rim within 14 km of Phantom Ranch stands more than 1,400 m above the canyon floor.⁶

   The drive turns the feature's direction to face the viewer and glides the camera to it; the test checks the turn and the map's heights round the listed center.

7. Correct

   A tap flies to Hawaii, with Mauna Kea and Mauna Loa at 19.6°, -155.5° east, and the map shows it there. The island's highest point on the map is over 4,000 m, within 50 km of the listed point.⁷

   The drive turns the feature's direction to face the viewer and glides the camera to it; the test checks the turn and the map's heights round the listed center.

8. Not yet checked

   A tap names the place under it: the nearest city or peak, the state or province and the country (or the sea or lake), from Natural Earth.⁸

   tools/sp3-places.mjs draws Natural Earth 1:10m polygons into maps of 2 arc-minutes (about 3.7 km) and keeps the cities and peaks as points; src/space/places.js reads them. tests/sp3.spec.mjs checks Paris, Mount Everest, Denver, Sydney, Tokyo and the Atlantic, and a tap on Paris and on Everest in the browser.

9. Not yet checked

   Zoomed in, the ground comes from close-up tiles of the same maps, finer than the global map (the scales are in src/space/zoom.js); a feature named as a circle is an approximation of its real outline.¹

   tools/sp3-tiles.mjs averages each source into 10° tiles; tests/sp3.spec.mjs checks each world's tiles against its global map at a named feature.

1. 1Blue Marble: Next Generation (July 2004), NASA Earth Observatory (Reto Stöckli)
2. 2ETOPO 2022 Global Relief Model (60 and 15 arc-seconds), NOAA National Centers for Environmental Information
3. 3Black Marble 2016 (Earth at Night), NASA Earth Observatory (Joshua Stevens, Miguel Román)
4. 4Earth Fact Sheet, NASA Space Science Data Coordinated Archive
5. 5Mount Everest, Wikipedia
6. 6Grand Canyon; Phantom Ranch, Wikipedia
7. 7Mauna Kea, Wikipedia
8. 8Natural Earth 1:10m vectors, Natural Earth

Simplified

The relief is exaggerated by default (ten or twenty times; Pluto, Ceres and Vesta are drawn at true height), as chosen and labeled in the Splash tab; close up during a fly it eases to at most twice its height. True height is one choice away.

Simplified

The world turns thousands of times faster than real (labeled in the Splash tab: an hour or a day each second).

Simplified

North is always up and the sun stays near the equator's plane: the axial tilt and the seasons are left out.

Simplified

The sun shades each slope by the cosine of its angle to the sun (Lambert's law) and leaves the night side dark, but nothing casts a shadow, and real surfaces scatter light in more complicated ways.

Simplified

The global map has about 1,000 by 500 heights and 2,000 by 1,000 colors; only the patches round the named features are sharper.

Simplified

The oceans are drawn flat at sea level; there are no clouds; the blue rim of air is a drawn glow.

Simplified

The city lights are NASA's 2016 composite of cloud-free nights, not one night.

This link opens it in the Playground. To put it on your own page, add the element and one script tag. Every option.

https://splashery.app/play/?toy=real-earth

<script type="module" src="https://splashery.app/play/src/element.js"></script>
<splashery-toy toy="real-earth"></splashery-toy>