It doesn't look any smaller, but Denali is now officially 10 feet shorter than we thought.
The US Geological Survey set out to measure North America's tallest mountain this summer, and found a big surprise: Though it's still the tallest mountain in North America, Denali is only 20,310 feet high.
The last measurement, at 20,320 feet, was taken in 1953.
Researchers aren't sure if the difference is due to geological changes, or advances in technology.
Back in 1953, surveyors basically measured elevation by sight, according to Kari J. Craun, director of the USGS National Geospatial Technical Operations Center.
They would start at a known point, she told Tech Insider, and go from place to place measuring the mountain.
Surveyors would then use their measurements to determine the distance and elevation of the mountain using the Pythagorean Theorem — an equation you likely learned in math class in high school to find the length of one side of a triangle using the other two sides.
Since they could only measure as far as they could see with the instruments they had, this method was a painstakingly long process.
Today, surveyors use GPS to get the job done in a lot less time. The climbing team of four took only a few weeks to make their measurements once they reached the summit of Denali, which was called Mount McKinley until President Obama restored its Native American name in August.
Their data collection was similar to the way your smartphone connects to GPS, Craun said, but they gathered it for a longer period of time so it was more accurate. While elevation can be measured using sonar technology in airplanes or satellites in space, the most precise method is still to get it on the ground.
This more accurate measurement of the summit will be helpful for aviation safety and researchers, Craun said.
Whether the mountain shrunk is unknown, Craun said, because the previous measurement could have just been wrong.
"The only thing we do know is we have a more accurate idea of where the summit is now than we did before," she said. "If we ever decide to measure this point again, then we will have a better baseline and we will know then if something has changed."
