This image shows magnetic anomalies in the South Pacific — underwater lines where the crust of the Earth either matches up with the planet's overall magnetic polarity (reds and purples) or is completely reversed (blues). Invisible to the naked eye, these stripes run along all of Earth's ocean basins. We first noticed them in the 1950s and, at first, they were a giant mystery. Why would there be these distinct lines of magnetism, and why would the lines fluctuate in their polarity? As Chris Rowan explains at the Highly Allochthonous blog, the answer ended up being a key part of proving that chunks of the Earth's crust were moving away from each other.
Fred Vine and Drummond Matthews thought through the consequences of the hypothesis put forward by Harry Hess, that new oceanic crust was being continuously produced by the eruption of basalt at mid-ocean ridges. When combined with the facts that newly cooled basalt has a strong remanent magnetisation aligned with the ambient magnetic field, and that the Earth’s magnetic field reverses its polarity every million years or so. Vine and Matthews* argued that if seafloor spreading was indeed occurring at mid-ocean ridges, then linear positive and negative magnetic anomalies, formed from crust produced in normal and reversed polarity chrons, would form a symmetric pattern around the mid-ocean ridges, which is exactly what we see.
Landsat is a United States satellite program that's been in operation since 1972. Eight different satellites (three of them still up there and functioning) have gathered images from all over the world for decades. This data is used to help scientists studying agriculture, geology, and forestry. It's also been used for surveillance and disaster relief.
Today is the 40th anniversary of the "Blue Marble," the iconic photo taken by the crew of the Apollo 17. More on the photo and its impact at LIFE.com and Wikipedia. Here's NASA's original caption:
View of the Earth as seen by the Apollo 17 crew traveling toward the moon. This translunar coast photograph extends from the Mediterranean Sea area to the Antarctica south polar ice cap. This is the first time the Apollo trajectory made it possible to photograph the south polar ice cap. Note the heavy cloud cover in the Southern Hemisphere. Almost the entire coastline of Africa is clearly visible. The Arabian Peninsula can be seen at the northeastern edge of Africa. The large island off the coast of Africa is Madagascar. The Asian mainland is on the horizon toward the northeast."
John Streeter, who is a television producer with NASA at Johnson Space Center in Houston, sends this cool video and tells Boing Boing:
It is all real, all shot from the International Space Station and all beautiful. It is time-lapse photography that showcases stars, cities at night, lightning storms and the aurora all from the vantage point of the space station. Also, there is a link at the end where you can visit, download and create your own videos if you wish.
The station is a remarkable engineering achievement and this is just a small side benefit of being in orbit. I hope you enjoy.
Philip Bump put together this great comparison of Earth's Mt. McKinley and Mars' Mt. Sharp (as photographed by the Curiosity rover).
Officially, it's Aeolis Mons, and it stands 18,000 feet above the crater floor. Here's how that compares to Mount McKinley, America's tallest peak at 20,320 feet. The sea levels / floor levels are roughly comparable. But this is just an approximation. Do not make wagers based on this.
Today is the final day for voting in the USGS "Earth as Art" image project. To celebrate the 40th Anniversary of the Landsat Program on July 23, 2012, the federal agency seeks your help in selecting the 5 coolest images from more than 120 scenes.
For 40 years Landsat satellites have been acquiring images of the land cover of the planet. The satellites have given us spectacular views of mountains, valleys, coastal areas, islands, volcanic fields, forests, and patterns on the landscape. By highlighting some of those features and creatively crafting the colors we have developed a series of "Earth as Art" perspectives that reveal the artistic side of Landsat. The Top 5 "Earth as Art" images will be announced on July 23 in Washington, D.C., at a special event commemorating the launch of the first Landsat satellite.
Image above, from the Landsat collection: Akpatok Island lies in Ungava Bay in northern Quebec, Canada. Accessible only by air, Akpatok Island rises out of the water as sheer cliffs that soar 500 to 800 feet (150 to 243m) above the sea surface. The island is an important sanctuary for cliff-nesting seabirds. Numerous ice floes around the island attract walrus and whales, making Akpatok a traditional hunting ground for native Inuit people.
Scientists have long speculated that large tsunamis could be linked to the calving of icebergs—where chunks of ice break off of the side of a glacier or ice shelf and float away. The Tohoku earthquake and tsunami that happened in March off the coast of Japan finally gave them much more direct evidence of this phenomenon. Fascinating stuff, and a great reminder of how interconnected the world really is.