ILLUMINATING THE POWER OF THE OVERVIEW EFFECT: ASTRONAUTS’ PHOTOGRAPHS OF EARTH FROM SPACE EXPAND UNDERSTANDING OF GLOBAL PROCESSES, INTERLINKED SYSTEMS, ENVIRONMENTAL CHANGES AND HUMAN IMPACTS

Upon viewing Earth from space, astronauts undergo a profound cognitive shift – the Overview Effect – borne of wonder and awe and fostered by perceptions of interconnection and fragility that instill a deep caring for Earth. How do surface-bound earthlings experience this effect? The 50-year-long photojournal of the planet, acquired by these trained observers, provides a means. Rusty Schweickart (Apollo 9) stated, “When you go around the Earth in an hour and a half…it comes through to you so powerfully that you’re the sensing element for Man.” As such, a task on the mission timeline for both Space Shuttle and International Space Station crews has been to photograph ephemeral events (e.g., volcanic eruptions) and dynamic complexes (deltas). Those 2-dimensional photos are awe-inspiring, large-scale, true-color views of landforms and surficial processes. Stereophoto strips enable 3-dimensional structural interpretation. Extended time series of images enable quantitative analysis of change on a decadal scale (glaciers) – the 4^th dimension.

Astronauts’ photographs portray clear relationships among all Earth’s spheres and human endeavors. Views of surface systems such as reefs and atolls depict a biosphere connected with geosphere and hydrosphere. Those of weather systems show linkages between the atmosphere and hydrosphere. Some illustrate inputs of Earth material into the atmosphere by volcanoes and dust blows and show build-ups of windblown sand. Erosional features like river-cut landscapes and glaciated terrains reveal work done by hydrosphere on geosphere. Lake-level fluctuations indicate short-term environmental changes. Architectural details of entire orogens reflect slower internal processes, whereas impact craters reveal catastrophic surface changes.

Humans are integral to the Earth system – agents of short-term environmental impact and changes. Rapid urbanization is quantifiable. Deltas show input of sediment into the hydrosphere, enhanced by human activities. Smog and smoke show inputs into the atmosphere. Photos of pivot irrigation systems in drylands indicate groundwater extraction, and others show rain forest destruction. Analyzing these photographic data expands our capability to document, interpret and monitor Earth’s surface and illuminates our collective Earth-bound oneness.