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Tag Archives: Earth

From a report in the New York Times by Nicholas St Fleur:

Continents cruise in the slow lane. Moving just millimeters at a time, it took the ancient supercontinent Pangea hundreds of millions of years to break apart into today’s landmasses. But a study published Tuesday shows that the journey wasn’t always a leisurely drive. When under extreme strain, the tectonic plates hit the throttle and accelerated to speeds 20 times faster than they were traveling before.

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Credit: Sascha Brune

After analyzing seismic data from across the world and building a model, a team of geophysicists have discovered that plates move in two distinct phases: a slow phase and a fast one. During the slow phase, the continental crusts, which can be more than 20 miles thick, are stretched out little by little while remaining connected. But then suddenly, one or both of the continents step on the gas pedal. A critical point is reached when the connection between the two continents becomes so weak it can no longer resist the forces trying to pull it apart. This acceleration is directly related to the thinning of the crust.

Links: NYT article; computer simulation illustrating the movement of different continents.

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From a NASA press release, July 20, 2015:

A NASA camera on the Deep Space Climate Observatory (DSCOVR) satellite has returned its first view of the entire sunlit side of Earth from one million miles away.

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Credit: NASA/NOAA/USAF

This color image of Earth was taken by NASA’s Earth Polychromatic Imaging Camera (EPIC), a four megapixel CCD camera and telescope. The image was generated by combining three separate images to create a photographic-quality image. The camera takes a series of 10 images using different narrowband filters — from ultraviolet to near infrared — to produce a variety of science products. The red, green and blue channel images are used in these color images.

The image was taken July 6, 2015, showing North and Central America. The central turquoise areas are shallow seas around the Caribbean islands. This Earth image shows the effects of sunlight scattered by air molecules, giving the image a characteristic bluish tint. The EPIC team is working to remove this atmospheric effect from subsequent images. Once the instrument begins regular data acquisition, EPIC will provide a daily series of Earth images allowing for the first time study of daily variations over the entire globe. These images, available 12 to 36 hours after they are acquired, will be posted to a dedicated web page by September 2015.

The primary objective of DSCOVR, a partnership between NASA, the National Oceanic and Atmospheric Administration (NOAA) and the U.S. Air Force, is to maintain the nation’s real-time solar wind monitoring capabilities, which are critical to the accuracy and lead time of space weather alerts and forecasts from NOAA.

Links: NASA press release, DSCOVR homepage.

Abridged from a New Scientist article by Rebecca Boyle, September 30, 2014:

A newly discovered asteroid called 2014 OL339 is the latest quasi-satellite of Earth – a space rock that orbits the Sun but is close enough to Earth to look like a companion. The asteroid has been hanging out near Earth for about 775 years, but its orbit is unstable – it will probably move on about 165 years from now.

Credit: NASA

Credit: NASA

Quasi-satellites orbit in resonance with Earth, allowing our planet’s gravity to shift the rock’s position. The asteroid orbits the Sun every 365 days, as Earth does, but Earth’s gravity guides it into an eccentric wobble, which causes the rock to appear to circle backward around the planet.

The asteroid, which is between 90 and 200 metres in diameter, is among several different categories of space rock in Earth’s retinue besides our one satellite, the Moon. Rocks that hang out at a gravitational middle ground known as a Lagrange point, where they follow or lead Earth in its orbit, are called Trojans.

Links: The full New Scientist article; NASA’s Near-Earth Object program.

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Credit: Bill Anders/NASA

To commemorate the 45th anniversary of Apollo 8, the first manned mission to orbit the Moon, a new computer-generated visualization has been released to tell the story of one of space’s most famous images. The movie uses high-precision data from NASA’s Lunar Reconnaissance Orbiter, LRO, to accurately recreate the event.

Links: NPR article and interview with the movie’s narrator Andrew Chaikin; NASA press release.

On July 19, 2013, NASA’s Cassini spacecraft captured color images of Earth and the Moon from its perch in the Saturn system nearly 900 million miles (1.5 billion kilometers) away.  Earth and the Moon appear as mere specks – Earth a ‘pale blue dot’ and the Moon a stark white, visible between Saturn’s rings. It was the first time Cassini’s highest-resolution camera captured Earth and its moon as two distinct objects.

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Credit: NASA/JPL-Caltech/Space Science Institute

The MESSENGER probe, orbiting Mercury, also snapped pictures of our home planet. Full details and further images may be found in this JPL press release.