Nearing the Summer Solstice


The summer solstice on Saturn that is.  Superb!

The original caption:

Since NASA’s Cassini spacecraft arrived at Saturn in mid-2004, the planet’s appearance has changed greatly. The shifting angle of sunlight as the seasons march forward has illuminated the giant hexagon-shaped jet stream around the north polar region, and the subtle bluish hues seen earlier in the mission have continued to fade. Earlier views obtained in 2004 and 2009 (seePIA06077 and PIA11667) demonstrate how drastically the illumination has changed.

This view shows Saturn’s northern hemisphere in 2016, as that part of the planet nears its northern hemisphere summer solstice in May 2017. Saturn’s year is nearly 30 Earth years long, and during its long time there, Cassini has observed winter and spring in the north, and summer and fall in the south. The spacecraft will complete its mission just after northern summer solstice, having observed long-term changes in the planet’s winds, temperatures, clouds and chemistry.

Cassini scanned across the planet and its rings on April 25, 2016, capturing three sets of red, green and blue images to cover this entire scene showing the planet and the main rings. The images were obtained using Cassini’s wide-angle camera at a distance of approximately 1.9 million miles (3 million kilometers) from Saturn and at an elevation of about 30 degrees above the ring plane. The view looks toward the sunlit side of the rings from a sun-Saturn-spacecraft angle, or phase angle, of 55 degrees. Image scale on Saturn is about 111 miles (178 kilometers) per pixel.

The exposures used to make this mosaic were obtained just prior to the beginning of a 44-hour movie sequence (see PIA21047).

Image: NASA/JPL-Caltech/Space Science Institute


Gancedo Meteor

What a find!

About 4,500 years ago a huge meteor hit Argentina.  It was found a few days ago on 10 September by explorers from the Astronomy Association of the Chaco (Asociación de Astronomía del Chaco).   Chaco is a province of Argentina and the meteor fall area is located in the southwestern part of the province in the town of Gancedo.

When I saw this on the news I had to go to Impact Earth and see what would happen if this hit near me.   Try it.



Long Filament on the Sun


sSO gives us a look at pair of unusually long filaments on the Sun.

The two most noteworthy features on the sun this week were a pair of elongated filaments (Sept. 8, 2016). The central one was twisted into the shape of an elaborate arch at the center of the sun (yellow arrows). If this were straightened out, it would extend just about across the entire sun, almost a million miles (1.6 million Km). The other, smaller filament, (white arrows) if made straight, might reach about half that distance. Still, pretty impressive. Filaments are elongated strands of plasma suspended above the sun by magnetic forces. They are notoriously unstable and often break apart within a few days. The image was made by combining three images in different wavelengths of extreme ultraviolet light.

Credit: Solar Dynamics Observatory, NASA.

Shadowed Saturn


Saturn’s shadow stretched beyond the edge of its rings for many years after Cassini first arrived at Saturn, casting an ever-lengthening shadow that reached its maximum extent at the planet’s 2009 equinox. This image captured the moment in 2015 when the shrinking shadow just barely reached across the entire main ring system. The shadow will continue to shrink until the planet’s northern summer solstice, at which point it will once again start lengthening across the rings, reaching across them in 2019.

Like Earth, Saturn is tilted on its axis. And, just as on Earth, as the sun climbs higher in the sky, shadows get shorter. The projection of the planet’s shadow onto the rings shrinks and grows over the course of its 29-year-long orbit, as the angle of the sun changes with respect to Saturn’s equator.

This view looks toward the sunlit side of the rings from about 11 degrees above the ring plane. The image was taken in visible light with the Cassini spacecraft wide-angle camera on Jan. 16, 2015.

The view was obtained at a distance of approximately 1.6 million miles (2.5 million kilometers) from Saturn. Image scale is about 90 miles (150 kilometers) per pixel.

Credit: NASA/JPL-Caltech/Space Science Institute

Gemini 11 – 50 Years ago

Astronauts Charles “Pete” Conrad, Jr. and Richard F. Gordon, Jr. performed the first-ever first orbit rendezvous with an Agena Target Vehicle, docking with it one hour and thirty-four minutes after launch paving the way to the future of space travel.


Leaving Murray Buttes


The roving Mars Science Laboratory Curiosity is leaving Murray Buttes and those fabulous layered rocks. To be more accurate Murray Buttes is a region on Mount Sharp and is a great example of wind in action.

The buttes and mesas rising above the surface in this area are eroded remnants of ancient sandstone that originated when winds deposited sand after lower Mount Sharp had formed. Curiosity closely examined that layer — called the “Stimson formation” — during the first half of 2016, while crossing a feature called “Naukluft Plateau” between two exposures of the Murray formation. The layering within the sandstone is called “cross-bedding” and indicates that the sandstone was deposited by wind as migrating sand dunes.

The image was taken on Sept. 8, 2016, during the 1454th Martian day, or sol, of Curiosity’s work on Mars. — NASA

Image: NASA/JPL-Caltech/MSSS

Sounds of Jupiter’s Aurora

The frequency range of these signals is from 7 to 140 kilohertz. Radio astronomers call these “kilometric emissions” because their wavelengths are about a kilometer long.

Let’s see, the wavelength of a 7 kHz signal is:

λ = speed of light (c) / 7 kHz or 7000 hertz


λ = 300,000,000 m/s / 7,000 Hz

λ = 42,857 m or 42.857 km



Sentinel-1A Damaged


The power producing solar panels on the Sentinel-1A satellite have been damaged by an impact of some sort. The impacting object was tiny, in the few-millimetres class tiny. The image above from ESA shows the damage.

Even an impact with such a tiny object makes a difference:

A sudden small power reduction was observed in a solar array of Sentinel-1A, orbiting at 700 km altitude, at 17:07 GMT on 23 August. Slight changes in the orientation and the orbit of the satellite were also measured at the same time. — ESA

Sentinel 1A operations have not been impacted. There are in excess of 19,000 bits of known space debris, luckily this one was small.

The in-depth story from ESA.