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USGS Global Visualization Viewer
Click on a world map to zoom in on and browse a continuous mosaic of recent
cloud-free satellite images choosing from a range of datasets. Display topographical maps, explore archived satellite images.
National Geographic MapMaker
A digital mapping tool created by the National Geographic Society and Esri,
designed for teachers, students, and National Geographic Explorers, enabling users to examine maps and data to explore the Earth’s interconnected systems. Display biomes, plate tectonics, population density, light pollution, human footprint, topographical contours and more.
Great Circle Calculator
Calculate ellipsoidal Great Circle distance and forward & back azimuth from coordinates.
Surface Distance Calculator
Calculate great circle distance between cities, and surface distance between points of latitude and longitude.
Assumes Earth to have a spherical radius of 6366.707 km.
The JavaScript on this page was largely used to create the distance & direction finder on the
locate page of the earthdirections site.
Magnetic Declination Calculator
Geomagnetic declination calculator, from NOAA.
IGRF Geomagnetic Model Tool
Display and download IGRF magnetic field maps.
GMT
Generic Mapping Tools “...an open-source collection of command-line tools for manipulating geographic and Cartesian data sets ...
producing high-quality illustrations ranging from simple x–y plots via contour maps to artificially illuminated surfaces and 3D perspective views. It supports many map projections and transformations and includes supporting data such as coastlines, rivers, and political boundaries and optionally country polygons.”
iGMT
Graphical interface for using GMT on Linux / Unix platforms, source available on
github.
QGIS
A Free and Open Source Geographic Information System (GIS) software, for working with geospatial data and generating maps.
An alternative to proprietary software such as Esri.
Here’s a good
introductory article on QGIS,
an interesting project using QGIS to apply a 1777 style to current OpenStreetMap data, and
an interview with the founder of QGIS, Gary Sherman.
OpenStreetMap
A free, open map database updated and maintained by a community of volunteers via open collaboration. Contributors collect data from surveys, trace from aerial photo imagery or satellite imagery, and import from other freely licensed geodata sources.
PROJ
Cartographic Projections and Coordinate Transformations Library “...a generic coordinate transformation software that transforms geospatial coordinates from one coordinate reference system (CRS) to another. This includes cartographic projections as well as geodetic transformations.”
Geodedic Programs: INVERSE, FORWARD, INVERS3D, FORWRD3D
From the National Geodetic Survey, software that computes the geodetic azimuth and distance between two points given their geographic positions, and the geographic position of a point given the geodetic azimuth and distance to another given point.
Executables and source code available for download
(README),
on-line interactive versions also available:
INVERSE,
FORWARD,
INVERS3D,
FORWRD3D.
Geodesy and Tcl
T. Vincenty’s algorithm “Direct and inverse solutions of geodesics
on the ellipsoid with application of nested equations” within Tcl code.
MERLIN
Multi-source EnviRonmental data dispLay for INternet archives—a Display
System for Environmental Data, a scientific tool for researchers investigating
global change and climate issues.
World Wind
Planetary globe 3D engine
from NASA, “… allows application developers to quickly and easily create interactive visualizations of geographical information in a 3D planetary context … monitor weather patterns, visualize cities and terrain, track vehicle movements, analyze geospatial data and educate humanity about the Earth.” Different from a 3D globe like Google Earth as it’s not an application but an SDK that can be used to build applications. Provides a geographic rendering engine for powering projects ranging from satellite tracking systems to flight simulators. Open source software, source available on github.
GPlates
“A desktop software for the interactive visualisation of plate tectonics … offers a novel combination of interactive plate tectonic reconstructions, geographic information system (GIS) functionality and raster data visualisation … visualisation and manipulation of plate tectonic reconstructions and associated data through geological time … runs on Windows, Linux and macOS.” See the online user manual and tutorials. For an example of something created with GPlates, use ancient-earth to see what Earth looked like going back up to 750 million years, illustrating the shifting movement of continents and locations of where current cities would be.
Geodesy For The Layman
Open Source book on Geodesy, the measurement and representation of the shape
and size of the earth and its gravitational field.
Navigation on the Spheroidal Earth
Determine navigational geometry along the surface of an oblate spheroid (the shape Earth closely approximates),
includes formulas and diagrams.
Calculating great circle distance
What is the best way to calculate the great circle distance (which deliberately ignores elevation differences) between 2 points?
This answer was prepared by Robert G. Chamberlain of Caltech (JPL) and reviewed on the comp.infosystems.gis newsgroup in Oct 1996.
Additional mirrors of this FAQ can be found here and within the full list of FAQs here.
Where in the world am I?
How to determine longitude and latitude, from the University of Cambridge’s
Millennium Mathematics Project.
Latitude and Longitude
Essay discussing parallels of latitude, meridians of longitude, right ascension &
declination, and the relationship between longitude and global time zones.
IGU
The International Geographical Union (IGU) is an international, non-governmental, professional organization devoted to the development of the discipline of Geography. The purposes of the IGU are primarily to promote Geography through initiating and coordinating geographical research and teaching in all countries of the world.
IUGG
The International Union of Geodesy and Geophysics (IUGG) is the international organization dedicated to advancing, promoting, and communicating knowledge of the Earth system, its space environment, and the dynamical processes causing change.
ASPRS
American Society for Photogrammetry and Remote Sensing “…to advance
knowledge and improve understanding of mapping sciences to promote the responsible
applications of photogrammetry, remote sensing, geographic information systems,
and supporting technology.” Check out the
Grids and Datums columns.
Open Geospatial Consortium
Non-profit, international, voluntary consensus standards organization leading
the development of standards for geospatial and location based services.
IERS
International Earth Rotation and Reference Systems Service.
“The primary objectives of the IERS are to serve the astronomical, geodetic and geophysical communities by providing data and standards related to Earth rotation and reference frames.”
INTERMAGNET
International Real-time Magnetic Observatory Network, the global network of
geomagnetic observatories that monitor Earth’s magnetic field
Geodetic Resources
Links to geodetic resources – National Geodetic Survey.
Online Map Resources, Cambridge University
Links to resources for Online Maps, GIS, Route Finders, etc. – Cambridge University Library
GEOID Home Page
From the National Geodetic Survey (NGS), the geoid is the “equipotential surface of the Earth’s
gravity field which best fits, in a least squares sense, global mean sea level.”
Read more here: What is the geoid?
Blue Marble
“…the most detailed true-color image of the entire Earth to date…a
collection of satellite-based observations…seamless, true-color mosaic of
every square kilometer of our planet…freely available to educators, scientists,
museums, and the public.”
Earth Observatory, NASA
“…The Earth Observatory’s mission is to share with the public the
images, stories, and discoveries about the environment, Earth systems, and climate
that emerge from NASA research, including its satellite missions, in-the-field research, and models.”
Earth Observation Portal
“…a gateway to knowledge and resources related to Earth Observation
satellite missions … access point for information and services from Earth Observation
… direct access to earth-observing satellite data as well as map servers and cartographic
resources … operated by the European Space Agency (ESA) to serve as an information
source to the Earth observation, space, and broader community.”
Global Change Master Directory
The GMCD is a directory of Earth science data and services from NASA, the goal of
which is to “enable users to locate and obtain access to Earth science data sets
and services relevant to the global change and Earth science research.”
This Dynamic Earth
From the USGS, an on-line book about the Story of Plate Tectonics.
Check out the historical perspective on
continental drift, see how a
hotspot forms the Hawaiian Islands.
Dispersal of Gondwanaland
Animation of the ancient meta-continent breaking up into the continents we know today.
Degree Confluence Project
“The goal of the project is to visit each of the latitude and longitude
integer degree intersections in the world, and to take pictures at each
location…another goal is to document the changes at these locations over time.”
Build a Solar System
A tool for calculating the orbit radii and diameters of planets in a scale model solar system, from the
Exploratorium.
Sun-Earth Day
NASA’s website to “increase science literacy and focus attention on the active Sun and its effects on Earth.”
International Society for Digital Earth
“Digital Earth makes use of digital technologies to model earth systems, including its cultural and social aspects represented by human societies living on the planet. The model is a multidimensional, multiscale, multitemporal, and multilayered information system. Digital Earth is envisaged as a common platform to support national and international cooperation for global sustainable development, and a newly-developing point of economic growth and social well-being.”