Saturn’s Rings

The rings of Saturn. Credit: NASA/JPL-Caltech/Space Science Institute


Cassini captured this image of the Saturn rings and the little moon Prometheus. I got to thinking about the early drawings, in particular the famous 1666 drawing by Robert Hooke showing the shadows from the planet and rings.


As an aside, Robert Hooke is probably one of the most famous scientists many school kids have never heard of.

From NASA’s Groovy:

From afar, Saturn’s rings look like a solid, homogenous disk of material. But upon closer examination from Cassini, we see that there are varied structures in the rings at almost every scale imaginable.

Structures in the rings can be caused by many things, but often times Saturn’s many moons are the culprits. The dark gaps near the left edge of the A ring (the broad, outermost ring here) are caused by the moons (Pan and Daphnis) embedded in the gaps, while the wider Cassini division (dark area between the B ring and A ring here) is created by a resonance with the medium-sized moon Mimas (which orbits well outside the rings). Prometheus is seen orbiting just outside the A ring in the lower left quadrant of this image; the F ring can be faintly seen to the left of Prometheus.

This view looks toward the sunlit side of the rings from about 15 degrees above the ringplane. The image was taken in red light with the Cassini spacecraft wide-angle camera on Jan. 8, 2015.

The view was obtained at a distance of approximately 566,000 miles (911,000 kilometers) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 37 degrees. Image scale is 34 miles (54 kilometers) per pixel.

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GK Persied

A colloboration of Chandra, Hubble, and VLA showing GK Persei.  Image Credit: NASA/CXC/RIKEN/D.Takei et al
A colloboration of Chandra, Hubble, and VLA showing GK Persei. Image Credit: NASA/CXC/RIKEN/D.Takei et al

Astronomers studied the famous 1901 nova with the Chandra X-ray Observatory (blue color) in February 2000 and again November 2013 with additional data from Hubble (yellow color), and the Very Large Array (pink). The 13-span provided some interesting data and new questions.

First a little backgound. In 1901 GK Persei suddenly became one of the brightest objects in the sky. It was a classic nova, one where material was collected by a white dwarf star from a companion star builds up to a point when nuclear fusion reactions can occur and the outer layers of the white dwarf are blown away by the explosion. The results of the explosion can be seen for weeks and sometimes years especially if we use world class observatories. Think of these explosions as mini-supernovae. Supernova are responsible for making the heavy elements that make planets, moons and even us. Studying these smaller explosions gives us clues to dynamics of larger one.

The debris from the nova has expanded of a speed around 1,126,510 kmh / 700,000 mph. That means in the 13 years between observations the blast wave moved over 144 billion km / 90 billion miles.

The luminosity of the Persei remnant has decreased by about 40 percent, that’s pretty reasonable but the temperature of the explosion has remained constant at about a million degrees Celsius. The temperature should have dropped, suggesting the blast wave is expanding into a region of lower density.

The optical data show clumps of material ejected in the explosion as expected, there is a point souce in the lower left of the image, the nature of which is unknown.

A more indepth explanation of the image can be found here.

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Abell 2256

The Abell 2256 region. Credit: NRAO


This isn’t just a galaxy collision, this is a whole cluster of galaxies colliding.

From the NRAO:

Researchers using the Karl G. Jansky Very Large Array (VLA) have produced the most detailed image yet of a fascinating region where clusters of hundreds of galaxies are colliding, creating a rich variety of mysterious phenomena visible only to radio telescopes.

The scientists took advantage of new VLA capabilities to make a “true color” radio image. This image shows the region as it would appear if human eyes were sensitive to radio waves instead of light waves. In this image, red shows where longer radio waves predominate, and blue shows where shorter radio waves predominate, following the pattern we see in visible light.

The image shows a number of strange features the astronomers think are related to an ongoing collision of galaxy clusters. The region is called Abell 2256, and is about 800 million light-years from Earth and some 4 million light-years across. The image covers an area in the sky almost as large as the full moon. Studied by astronomers for more than half a century with telescopes ranging from radio to X-ray, Abell 2256 contains a fascinating variety of objects, many of whose exact origins remain unclear.

Continue reading

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Total Eclipse This Week

There will be a Total Eclipse on 20 March. Will you be able to see it? If you are in most of Europe or northern Russia, you will get to be in the penumbra (a partial eclipse). The only populated places where the totality can be seen, reachable by public travel, are the Faroe Islands and Svalbard.

Either way be sure to check it out as this will be the last total eclipse visible in Europe until 12 August 2016.

The little graphic below from NASA will give you an idea what time the eclipse will occur and where.


I will not get to see it. I’m sure there will be sites that will be streaming the eclipse and I’ll like a few of them later this week.



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MMS Launch

The Magnetospheric Multiscale (MMS) mission (NASA) launched March 12 aboard a United Launch Alliance Atlas V rocket from Cape Canaveral Air Force Station in Florida.

The mission features four identical observatories to orbit Earth to provide a view of magnetic reconnection in three dimensions.


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Curiosity On the Move

The map covers an area about 300 yards (275 meters) across. North is up. The yellow lines indicate the route driven by Curiosity between Sol 751 (the 751st Martian day of the mission, on Sept. 16, 2014) and Sol 903 (Feb. 19, 2015).  Image and caption: NASA/JPL-Caltech/Univ. of Arizona
The map covers an area about 300 yards (275 meters) across. North is up. The yellow lines indicate the route driven by Curiosity between Sol 751 (the 751st Martian day of the mission, on Sept. 16, 2014) and Sol 903 (Feb. 19, 2015). Image and caption: NASA/JPL-Caltech/Univ. of Arizona

In the last Curiosity post the rover had undergone a fault condition. A “transient short circuit” triggered an on-board fault-protection program to halt activity on 27 February. The mission team took a few days to test and determine the cause. In the meantime a sample from a Telegraph Hill drilling was held for testing. Satisfied the problem has been cleared, the rover continues on and the sample has been delivered to the on-board laboratory.

The plan is drive Curiosity through the Artist’s Drive valley to reach higher layers of Mount Sharp.

The map was made in part from data from the HiRISE camera on the Mars Reconnaissance Orbiter.

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Storm Watch

The sun emitted a solar flare on 11 March 2015 and was captured in this excellent video by NASA and the Solar Dynamics Observatory. The flare was a powerful X2.2 class flare.

The “X” classification denotes the most intense flares. The number gives us a to gauge its relative strength compared to an X1 flare. A flare of X2 is twice the strong as an X1 and a 3 would be three times as strong. So the X2.2 classification pegs this flare as 2.2 times as strong as an X1.

The flare and not one but three coronal mass ejections (CME’s) prompted the US, Space Prediction Center (NOAA) to issue a Minor Geomagnetic Storm watch (Level G1).

The peak of the storm is expected to occur around 0100 to 0700 UTC on 13 March. Thats 2100 EDT 12 March to 0300 EDT 13 March in the US. If you want to see an aurora keep an eye on the sky around these times and please know these times are good estimates but there could be some deviation.

I should be near a computer today and will post updates as needed/available as edits to this post.

The NOAA Space Prediction Center will have current information and conditions.


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Radar View of Venus

Venus by radar. Credit: B. Campbell, Smithsonian, et al., NRAO/AUI/NSF, Arecibo
Venus by radar. Credit: B. Campbell, Smithsonian, et al., NRAO/AUI/NSF, Arecibo

The image is the result of combining the capabilities of the National Science Foundation’s Green Bank Telescope and radar transmitter at Arecibo Observatory to make a radar image of Venus.

Mountains and other surface features are easy to see (click the image). The black band is an area to close to the “Doppler equator” to get good image data.

More at the National Radio Astronomy Observatory.

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The Saturn moon Iapetus from Cassini
The Saturn moon Iapetus from Cassini

Here’s an image of the Saturn moon Iapetus from the Cassini spacecraft. It is the third largest moon of Saturn with a diameter of 1,417 km / 914 miles or about 40 percent of our moon . Iapetus has density of 1.1 so we know it is made largely of ices.

It’s a strange moon. Take note of the dark spot, that’s not a shadow. Iapetus has a dark side to it that has nothing to do whether or not it is facing the Sun. What causes the asymmetry? There are a few theories, the latest (and my new favorite) is due to ice migration in what is known as the Thermal Runaway Model.

Check out our Iapetus page for more images and more about the moon including physical details.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. NASA’s Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA’s Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

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