Surveyors are often seen in the middle of the street making careful measurements of angles with their transits, and distances with their steel tapes. For points than can be easily reached, such a survey is convenient. But when the target is inaccessible – a mountain summit or a distant star – known distances can be combined with measured angles to determine a distance or altitude. The method relies on parallax, the way an object appears to move, relative to a more distant background, when viewed from different angles.

On February 4, 1999, the 639-foot freighter New Carissa became grounded near Coos Bay on the Oregon coast. Aboard the ship were 400,000 gallons of bunker fuel, threatening to leak from the fractured hull and damage the state's fragile beach habitats. With an approaching storm increasing the chances of a disastrous spill, authorities decided to set the ship afire, a choice not without controversy and risks of its own. An oceanographer friend and I became curious about the extent of the disaster associated with the potential spill.