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NASA’s Solar Dynamics Observatory Takes a Spin

On July 6, 2016, engineers instructed NASA’s Solar Dynamics Observatory, or SDO, to roll 360 degrees on one axis. SDO dutifully performed the seven-hour maneuver, while producing some dizzying data: for this period of time, SDO images – taken every 12 seconds – appeared to show the sun spinning, as if stuck on a pinwheel.
This video was taken by SDO’s Atmospheric Imaging Assembly instrument in extreme ultraviolet wavelengths that are typically invisible to our eyes, but was colorized here in gold for easy viewing.

This maneuver happens twice a year to help SDO’s Helioseismic and Magnetic Imager, or HMI, instrument take precise measurements of the solar limb, the outer edge of the sun as seen by SDO. Were the sun perfectly spherical, this would be a much simpler task. But the solar surface is dynamic, leading to occasional distortions. This makes it hard for HMI to find the sun’s edge when it’s perfectly still.
HMI’s biannual roll lets each part of the camera look at the entire perimeter of the sun, helping it map the sun’s shape much more precisely.

HMI tracks variations in the solar limb over time to help us understand how the shape of the sun changes with respect to the solar cycle, the sun’s 11-year pattern of solar activity. The more we know about what drives this activity – activity that can include giant eruptions of solar material and radiation that can create hazards for satellites and astronauts – the better we may someday predict its onset.

► Source>>

Image credits: NASA’s Goddard Space Flight Center/SDO/Joy Ng

Further reading

► Solar Dinamic Observatory>>

#SolarSystem, #SolarDynamicsObservatory , #NASA , #HelioseismicMagneticImager , #SunActivity , #SolarEruptions
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Jupiter and the Great Red Spot

Jupiter's trademark Great Red Spot - a swirling anticyclonic storm feature larger than Earth - has shrunken to the smallest size ever measured. Astronomers have followed this downsizing since the 1930s.

"Recent Hubble Space Telescope observations (dating back to 2014) confirm that the Great Red Spot (GRS) is now approximately 10,250 miles across, the smallest diameter we've ever measured," said Amy Simon of NASA's Goddard Space Flight Center in Greenbelt, Md. Historic observations as far back as the late 1800s gauged the GRS to be as big as 25,500 miles on its long axis. The NASA Voyager 1 and Voyager 2 flybys of Jupiter in 1979 measured the GRS to be 14,500 miles across.

Starting in 2012, amateur observations revealed a noticeable increase in the spot's shrinkage rate. The GRS's "waistline" is getting smaller by 580 miles per year. The shape of the GRS has changed from an oval to a circle. The cause behind the shrinking has yet to be explained.

"In our new observations it is apparent that very small eddies are feeding into the storm," said Simon. "We hypothesized that these may be responsible for the accelerated change by altering the internal dynamics and energy of the Great Red Spot."

Simon's team plans to study the motions of the small eddies and also the internal dynamics of the GRS to determine if these eddies can feed or sap momentum entering the upwelling vortex.

In the comparison images one Hubble photo was taken in 1995 when the long axis of the GRS was estimated to be 13,020 miles across. In a 2009 photo, the GRS was measured at 11,130 miles across.

► Source>>

Credit: NASA, ESA, and A. Simon (Goddard Space Flight Center)

Acknowledgment: C. Go, H. Hammel (Space Science Institute, Boulder, and AURA), and R. Beebe (New Mexico State University)

Further reading

► Jupiter's Great Red Spot Viewed by Voyager 1>>

► Hubble Captures New Changes in Jupiter’s Great Red Spot>>

#HubbleTelescope, #Jupiter , #SolarSystem  , #GreatRedSpot , #Voyager1_2  

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Is There an Ocean Below Sputnik Planum on Pluto?

Today, APoD has shared an interesting picture about Sputnik Planum on Pluto.
Let's see what it is.

Sputnik Planum is a basin 900 kilometers across that makes up the western lobe in the famous heart-shaped feature, revealed during the New Horizons flyby.
The basin appears to have been created by an impact, likely by an object 200 kilometers across or larger.

Ever since NASA’s New Horizons spacecraft flew by Pluto last year, evidence has been mounting that the dwarf planet may have a liquid ocean beneath its icy shell. In fact, by modeling the impact dynamics that created the previous mentioned massive crater on Pluto’s surface, a team of researchers made a new estimate of how thick that liquid layer might be.

The study, led by Brown University geologist Brandon Johnson and published in Geophysical Research Letters, finds a high likelihood that there’s more than 100 kilometers of liquid water beneath Pluto’s surface. The research also offers a clue about the composition of that ocean, suggesting that it likely has a salt content similar to that of the Dead Sea.

I shared a post on this topic, about a month ago.
Take a look at that one>>

Image explanation: The unusually smooth 1000-km wide golden expanse, visible in the featured image from New Horizons, appears segmented into convection cells. The featured image of Sputnik Planum, part of the larger heart-shaped Tombaugh Regio, was taken last July and shows true details in exaggerated colors. It offers clues about a possible subsurface ocean.
This high-resolution image combines blue, red and infrared images taken by the Ralph/Multispectral Visual Imaging Camera (MVIC). Pluto’s surface shows a remarkable range of subtle colors, enhanced in this view to a rainbow of pale blues, yellows, oranges, and deep reds. The bright expanse- that is the Sputnik Planum- has been found to be rich in nitrogen, carbon monoxide, and methane ices.
Image Credit: NASA, Johns Hopkins U./APL, Southwest Research Inst.

Further reading

► Pluto's brilliant 'heart'>>

► Sputnik Planitia>>

► Convection cells>>

#Solar_System, #Pluto, #PlutoHeart , #NewHorizons , #PlutoSputnikPlanum, #giantasteroidimpact, #PossibleBuriedOcean

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Intrepid Crater on Mars

On 2010, the robotic rover Opportunity chanced across a small crater on Mars. Pictured below is Intrepid Crater, a 20-meter across impact basin slightly larger than Nereus Crater that Opportunity chanced across 2009.

This image is in approximately true color but horizontally compressed to accommodate a wide angle panorama.

Intrepid crater on Mars carries the name of the lunar module of NASA's Apollo 12 mission, which landed on Earth's moon Nov. 19, 1969.
Apollo 12's lunar module Intrepid carried astronauts Alan Bean and Pete Conrad to the surface of Earth's moon while crewmate Dick Gordon orbited overhead in the mission's command and service module, Yankee Clipper.

NASA's Mars Exploration Rover Opportunity recorded this view of the crater during the 2,417th Martian day, or sol, of the rover's work on Mars (Nov. 11, 2010).

Beyond Intrepid Crater and past long patches of rusty Martian desert lie peaks from the rim of large Endeavour Crater, visible on the horizon.

Credit: Mars Exploration Rover Mission, Cornell, JPL, NASA

Further reading and references

#SolarSystem, #Apollo12Mission, #IntrepidCrater, #Mars, #Space, #NASA, #Opportunity

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