Taxonomy term


Benchmarks: November 22, 1859: "On the Origin of Species" published

By David B. Williams

About a decade ago, I was fortunate enough to hold in my hands a first edition of Charles Darwin’s “On the Origin of Species.” The green cover was cracked and frayed. The cardboard backing protruded through the torn corners. I put the book down and stared at it in awe. The owner of this book was Asa Gray, one of America’s greatest botanists, an important early American supporter of natural selection, and a friend of Darwin’s.

23 Nov 2009

Musical magnetic reversals

Although Earth’s magnetic field currently points toward the North Pole, the planet’s magnetic dipole flips direction every few hundred thousand years or so. Engebretson tracked the last 85 million years of these magnetic reversals, with higher pitches representing shorter polarities (a period of time when the direction of the magnetic field stays the same), and lower pitches longer ones.

22 Sep 2009

Earth tides in A major

Earth experiences small, millimeter-sized tides, called Earth tides. Using a dataset from NASA’s Jet Propulsion Laboratory in California from A.D. 1600 to A.D. 2200, Engebretson calculated the net gravitational force of the sun and the moon at particular intervals and then mapped them onto the A major scale.

22 Sep 2009

The cosmos on key

Engebretson’s latest project involves taking the orbital periods of all eight planets in the solar system and turning them into corresponding frequencies: Planets that have short orbits like Mercury have higher frequencies, whereas more distant planets with longer orbits like Neptune have lower frequencies.

22 Sep 2009

Benchmarks: September 16, 1987: Montreal Protocol Signed

Each year in late September to early October, atmospheric scientists watch with anticipation as ozone concentrations over Antarctica drop, opening a window in Earth’s defenses against harmful ultraviolet radiation. This ozone “hole” grew steadily in the 1990s and set a record for its size in 2006: At its peak, the hole covered an average area of 27 million square kilometers, approximately the size of North America. But scientists think that the overall ozone layer is on the slow road to recovery, thanks to the Montreal Protocol — one of the most successful international environmental agreements in history.
16 Sep 2009

Benchmarks: August 17, 1959: Hebgen Lake earthquake and landslide

By Callan Bentley

You’re camping in Montana, doing some fly fishing on the Madison River. You’ve had a full day of beautiful Big Sky country weather, and had fresh trout for dinner. In your campsite at the Rock Creek Campground, you go to bed satisfied and happy. It’s a nice enough evening that you sleep out in the open, to better appreciate the stars. The waters of the Madison gurgle by, gently lulling you to sleep while Orion shines above.

18 Aug 2009

Benchmarks: July 4, 1054: "Birth" of the Crab Nebula

On July 4, 1054, Chinese and Japanese astronomers observed a new, iridescent yellow point of light in the constellation Taurus. This “guest star,” said to be as bright as the moon, failed to disappear with the rising sun — for a month, it shone both night and day. Even after fading during daytime, it remained in the night sky for nearly two years, by some accounts. Historians and scientists think that this event was likely the supernova that created the Crab Nebula, one of the most spectacular and rare astronomical features in the known universe.
04 Jul 2009

June 9, 1938: Huang He Diversion: Largest Act of Environmental Warfare in History

By Nate Burgess

The Huang He (Yellow River) has been called “China’s Sorrow.” The name pays tribute to the millions killed by the river’s churning, muddy waters in a long history of dramatic diversions and massive floods. One of the most notable recent events in the river’s troubled history occurred in June 1938, when the Nationalist Chinese Army diverted the river to block invading Japanese troops. In both number of deaths and geographic scale, this event was the largest act of environmental warfare in modern history.

09 Jun 2009

Benchmarks: May 29, 1919: Solar eclipse "proves" relativity

By Nate Burgess

On May 29, 1919, the moon’s silhouette crept slowly over the sun, bringing premature night to observers in a broad swath of the Southern Hemisphere between South America and Africa. Few onlookers realized that this event would provide the first successful test of Albert Einstein’s theory of relativity.

01 Jun 2009