crater

Give the Moon a chance

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Waxing Gibbous Moon, by James Guilford. April 3, 2020.

by William Murmann, CAA President

I know the Moon is considered a nuisance by many of our members.  However, it does have many things worth looking at as it waxes and wanes during the month.  Every night presents something new to see.
Tonight {April 3, 2020} for example, we have a waxing nine-day Moon that is past first quarter.  Looking along the terminator, however, you can spot 52-mile diameter crater Tycho with its steep walls and magnificent ray system that shoots halfway across the Moon.
Farther to the Moon’s north, we have 56-mile diameter crater Copernicus with a collection of four to five thousand-foot mountain peaks in its center made by rebound energy immediately after the crater was created by its impactor.
And just below the Moon’s north polar region, we have the 61-mile diameter crater Plato, the famous “Black Lake.”  Plato is filled halfway with black lava.  On its western rim there is a 9,000-foot peak called Plato Zeta.
As the Moon wanes and the terminator from the setting Sun nears the western edge of the crater, a sharp, spiky shadow can be seen shooting about 30 miles across the crater floor just as the Sun hits Plato Zeta.  By luck, I happened to observing Plato at 4 a.m. one morning and saw the shadow at the exact moment when the setting Sun hit the peak and shot the shadow across the crater floor.
If you are up for a challenge, see if you can see Plato Zeta’s spiky shadow just as it appears.

 

Meteor crater discovered hidden by polar ice

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Animated GIF: Credit: NASA's Goddard Space Flight Center/Cindy Starr
Two views of the Hiawatha crater region: one covered by the Greenland Ice Sheet, and the second showing the topography of the rock beneath the ice sheet, including the crater. Credit: NASA’s Goddard Space Flight Center/Cindy Starr

An international team of researchers that includes a NASA glaciologist has discovered a 19-mile-wide meteorite impact crater hiding beneath more than half a mile of ice in northwest Greenland. This is the first impact crater of any size ever found under the polar ice sheets.

The group, led by researchers from the Centre for GeoGenetics at the Natural History Museum of Denmark, University of Copenhagen, worked for the past three years to verify their discovery, which was initially made in 2015 using NASA data. The researchers first spotted the crater in July 2015, while they were inspecting a new map of the topography beneath Greenland’s ice sheet that used ice-penetrating radar data primarily from NASA’s Operation IceBridge — a multi-year airborne mission to track changes in polar ice — and earlier NASA airborne missions in Greenland. The scientists noticed an enormous, previously unexamined circular depression under Hiawatha Glacier, sitting at the very edge of the ice sheet in northwestern Greenland.

Their finding is described in a study published on Nov. 14 in the journal Science Advances. The crater is roughly 1,000 feet deep and more than 19 miles in diameter, encompassing an area slightly larger than that comprised inside the Capital Beltway around Washington, D.C. Its dimensions place it among the 25 largest impact craters on Earth.

The crater formed when an iron meteorite more than half a mile wide smashed into northwest Greenland – but the timing of when the event happened remains a key question and one the researchers want to answer next. The authors put the range between less than three million years ago and as recently as less than 13,000 years ago. The resulting depression has since been covered by ice.

A narrated video outlines the discovery and includes data visualizations which can be found here: https://svs.gsfc.nasa.gov/4572

A new pockmark on the face of Mars

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Photo: New crater on Mars. Image Credit: NASA
A dramatic, fresh impact crater dominates this false-color image taken by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA’s Mars Reconnaissance Orbiter on Nov. 19, 2013.

NASA-JPL: Space rocks hitting Mars excavate fresh craters at a pace of more than 200 per year, but few new Mars scars pack as much visual punch as one seen in a NASA image released February 5, 2014.

The image from the High Resolution Imaging Science Experiment (HiRISE) camera on NASA’s Mars Reconnaissance Orbiter shows a crater about 100 feet (30 meters) in diameter at the center of a radial burst painting the surface with a pattern of bright and dark tones. (See a high-resolution version of the image here.)

The scar appeared at some time between imaging of this location by the orbiter’s Context Camera in July 2010 and again in May 2012. Based on apparent changes between those before-and-after images at lower resolution, researchers used HiRISE to acquire this new image on Nov. 19, 2013. The impact that excavated this crater threw some material as far as 9.3 miles (15 kilometers).

The Mars Reconnaissance Orbiter Project is managed by NASA’s Jet Propulsion Laboratory, Pasadena, Calif., for NASA’s Science Mission Directorate, Washington. JPL is a division of the California Institute of Technology in Pasadena. HiRISE is operated by the University of Arizona, Tucson. The instrument was built by Ball Aerospace & Technologies Corp., Boulder, Colo. Malin Space Science Systems, San Diego, built and operates the Context Camera.

For more information about the Mars Reconnaissance Orbiter, which has been studying Mars from orbit since 2006, visit http://www.nasa.gov/mro .