Astronomy Picture of the Week – Dawn’s Early Light

As usual until September, this is from Cassini’s Grand Finale…

The light of a new day on Saturn illuminates the planet’s wavy cloud patterns and the smooth arcs of the vast rings.

The light has traveled around 80 minutes since it left the sun’s surface by the time it reaches Saturn. The illumination it provides is feeble; Earth gets 100 times the intensity since it’s roughly ten times closer to the sun. Yet compared to the deep blackness of space, everything at Saturn still shines bright in the sunlight, be it direct or reflected.

This view looks toward the sunlit side of the rings from about 10 degrees above the ring plane. The image was taken with the Cassini spacecraft wide-angle camera on Feb. 25, 2017 using a spectral filter which preferentially admits wavelengths of near-infrared light centered at 939 nanometers.

The view was obtained at a distance of approximately 762,000 miles (1.23 million kilometers) from Saturn. Image scale is 45 miles (73 kilometers) per pixel.

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Astronomy Picture of the Week – Small Wonders (Cassini’s Grand Finale)

(This is 30 minutes late because I was a couple days late with GGS.)

Still on the Grand Finale, and as I said when this started, I’ll be staying here until it’s over, because yes, I’m mourning the end of Cassini’s mission. It’s an image of three of Saturn’s smaller ring moons.

I hope you enjoy this one. As always, click on the image for the .tif download…

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Astronomy Picture of the Week – Northern Summer on Titan

Another one from Cassini’s Grand Finale. And yeah, I’m a day late.

NASA’s Cassini spacecraft sees bright methane clouds drifting in the summer skies of Saturn’s moon Titan, along with dark hydrocarbon lakes and seas clustered around the north pole.

Compared to earlier in Cassini’s mission, most of the surface in the moon’s northern high latitudes is now illuminated by the sun. (See here for a view of the northern hemisphere from 2007.) Summer solstice in the Saturn system occurred on May 24, 2017.

The image was taken with the Cassini spacecraft narrow-angle camera on June 9, 2017, using a spectral filter that preferentially admits wavelengths of near-infrared light centered at 938 nanometers. Cassini obtained the view at a distance of about 315,000 miles (507,000 kilometers) from Titan.

As usual, click on the image for the .tif download…

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Astronomy Picture of the Week – Puzzled Iapetus

Yet another one from Cassini’s Grand Finale. Yup, it’s still going…

Iapetus is a world of contrast, with light and dark regions fitting together like cosmic puzzle pieces.

Cassini Regio on Iapetus (914 miles or 1,471 kilometers across) is covered in a layer of dark, dusty material creating a stark contrast to the much brighter region that surrounds it. This leads to the moon’s distinctive, two-toned appearance. To learn more about the cause of the contrast between regions, see Encountering Iapetus.

This view looks toward Saturn-facing hemisphere of Iapetus. North on Iapetus is up and rotated 20 degrees to the right. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on March 11, 2017.

The view was obtained at a distance of approximately 1.6 million miles (2.6 million kilometers) from Iapetus. Image scale is 9 miles (15 kilometers) per pixel.

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Astronomy Picture of the Week: Mimas Dwarfed

We continue with images from Cassini’s Grand Finale. This time, it’s an image from over Saturn’s north pole, with a teeny tiny dot, Mimas, in the upper right…

From high above Saturn’s northern hemisphere, NASA’s Cassini spacecraft gazes over the planet’s north pole, with its intriguing hexagon and bullseye-like central vortex.

Saturn’s moon Mimas is visible as a mere speck near upper right. At 246 miles (396 kilometers across) across, Mimas is considered a medium-sized moon. It is large enough for its own gravity to have made it round, but isn’t one of the really large moons in our solar system, like Titan. Even enormous Titan is tiny beside the mighty gas giant Saturn.

This view looks toward Saturn from the sunlit side of the rings, from about 27 degrees above the ring plane. The image was taken in green light with the Cassini spacecraft wide-angle camera on March 27, 2017.

The view was acquired at a distance of approximately 617,000 miles (993,000 kilometers) from Saturn. Image scale is 37 miles (59 kilometers) per pixel. Mimas’ brightness has been enhanced by a factor of 3 in this image to make it easier to see.

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That’s It. We’re Out. And the Earth is Dying.

(Warning… strong language)

h/t Caine…

First, from the Washington Post…

President Trump announced Thursday afternoon that he is withdrawing the United States from the landmark Paris climate agreement, an extraordinary move that dismayed America’s allies and set back the global effort to address the warming planet.

God fucking damnit. We’re really screwed.

Trump’s decision set off alarms worldwide, drawing swift and sharp condemnation from foreign leaders as well as top environmentalists and corporate titans, who decried the U.S. exit from the Paris accord as an irresponsible abdication of American leadership in the face of irrefutable scientific evidence.

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Astronomy Picture of the Week: The Keeler Gap

Another one from Cassini’s Grand Finale mission…

Here’s the text from the photo page; the image is below the fold (and, as usual, you can click on it for the tiff download)…

Before Cassini entered its Grand Finale orbits, it acquired unprecedented views of the outer edges of the main ring system. For example, this close-up view of the Keeler Gap, which is near the outer edge of Saturn’s main rings, shows in great detail just how much the moon Daphnis affects the edges of the gap.

This image was part of a mosaic that included Daphnis (The Realm of Daphnis).

Daphnis creates waves in the edges of the gap through its gravitational influence. Some clumping of ring particles can be seen in the perturbed edge, similar to what was seen on the edges of the Encke Gap back when Cassini arrived at Saturn in 2004.

This view looks toward the sunlit side of the rings from about 3 degrees above the ring plane. The view was acquired at a distance of approximately 18,000 miles (30,000 kilometers) from Daphnis and at a Sun-Daphnis-spacecraft, or phase, angle of 69 degrees. Image scale is 581 feet (177 meters) per pixel. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Jan. 16, 2017.

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