Greenland on the move
Source: NASA Visualization Explorer
100 million years ago, Greenland was on the move. On its tectonic plate, it travelled from a more southern location northward to its current Arctic position, and along the way passed over a mantle plume or hotspot that left a record of its journey in Greenland's rocks. A plume is an upwelling of hot rock, or magma, from hundreds of miles below Earth's surface. When the magma reaches the base of Earth's outer layer, which includes the crust that makes up the seafloor and continents, it heats up the rock above, effectively cooking it and altering its chemistry. For magnetic rocks common in Earth crust, heating causes them to lose their magnetism. NASA researchers used the altered chemistry of these magnetic rocks to create a heat map of Greenland, where they found the "scar" of its millennia-long journey over the hotspot. The scar extends from the northwest region to the southeast region of Greenland. Because the northwest region of Greenland moved off the plume earlier it is significantly cooler than the southeast. Tracking the movements of landmasses helps scientists understand their evolution through time. But more immediately, the heat information feeds sea-level-change models on Earth by helping scientists predict the behaviour of the massive ice sheet that covers Greenland. Watch the video to learn more.
Yellowstone Fire: Then and Now
Story by Ellen T. Gray
In the summer of 1988, a third of Yellowstone National Park’s verdant landscape was wiped out in a devastating wildfire. Images collected by USGS-NASA Landsat satellites have been able to follow the remarkable recovery of the land since then. Landsat instruments use visible and infrared light to differentiate between burned and healthy areas. Images taken right after the fire use false colour to show freshly burned land as dark red. The dark red areas are patchy, indicating that the fire did not totally burn everything in its path. The shades of the red span from dark red to light red to mark the varying severity of certain areas. In 2018, the burn scars were a pale, pinkish-tan indicating that the forest vegetation is recovering. The light green edges are young trees, which use and reflect sunlight differently than mature trees that appear dark green. Fire scientists and researchers have used these false-coloured images to understand the long-term effects of wildfire upon a landscape and the progression of recovery over the 1988-2018 period. Watch the videos to learn more.
Moon Craters a Window to Earth's Past
Story by Lonnie Shekhtman (Source: NASA Visualization Explorer)
By looking at the Moon a group of scientists is challenging our understanding of a part of Earth’s history. On Earth, asteroid impacts increased by two to three times starting around 290 million years ago. For decades many experts assumed that early Earth craters have been worn away by the wind, storms, and other geologic processes. This idea explained why Earth has fewer older craters than expected compared to other bodies in the solar system, but it made it difficult to find an accurate impact rate and to determine whether it had changed over time. But by studying data on Moon craters from NASA’s Lunar Reconnaissance Orbiter, scientists found the Moon and Earth have historically shared a similar rate of asteroid impacts. The surface of the Moon is riddled with both ancient craters mostly undisturbed by erosion and craters from modern-day impacts making it the most complete and accessible chronicle of the asteroid collisions that carved our young solar system – and collisions really did speed up 290 million years ago. Out in the universe, this should allow astronomers to better understand how celestial bodies experience asteroids impacts. At home on Earth, this revelation may have implications on the origin of life. Watch the video to learn more.
An Astronaut’s View of an Annular Eclipse
Source: NASA Earth Observatory
"Clyde’s Spot" on Jupiter
Source: NASA
Image credit: Image data: NASA/JPL-Caltech/SwRI/MSSS
This image from NASA’s Juno spacecraft captures several storms in Jupiter’s southern hemisphere Some of these storms, including the Great Red Spot at upper left, have been churning in the planet’s atmosphere for many years, but when Juno obtained this view of Jupiter, the smaller, oval-shaped feature at the centre of the image was brand new.
The new feature was discovered by amateur astronomer Clyde Foster of Centurion, South Africa. Early on the morning of May 31, 2020, while imaging Jupiter with his telescope, Foster noticed a new spot, which appeared bright as seen through a filter sensitive to wavelengths of light where methane gas in Jupiter's atmosphere has strong absorption. The spot was not visible in images captured just hours earlier by atmosphere has strong absorption. The spot was not visible in images captured just hours earlier by astronomers in Australia.
On June 2, 2020, just two days after Clyde Foster’s observations, Juno performed its 27th close flyby of
Jupiter. The spacecraft can only image a relatively thin slice of Jupiter's cloud tops during each pass. Although Juno would not be travelling directly over the outbreak, the track was close enough that the mission team determined the spacecraft would obtain a detailed view of the new feature, which has been informally dubbed “Clyde’s Spot.”
The feature is a plume of cloud material erupting above the upper cloud layers of the Jovian atmosphere. These powerful convective "outbreaks" occasionally erupt in this latitude band, known as the South Temperate Belt (JunoCam observed another outbreak at this latitude back on Feb. 7, 2018).
Comments
Post a Comment
Thank you for your valuable comment.