Tag: Saturn

The rings of Saturn

8:42 am

The rings of Saturn

Cool image time! The picture on right, cropped by me to show here, was taken by Cassini on April 2, 2016. You can see the moons Dione (on left) and Epimetheus (on right) above the rings. The full image can be seen here.

I am sure there is a lot of important science contained within this image. I post it here however not because of any scientific reason but entirely because it is simply damn spectacular. More than a decade after Cassini arrived at Saturn, every new picture of the planet’s giant ring system still seems incredibly unbelievable.

The universe is an amazing place, isn’t it?

5 comments

Saturn from Cassini

10:40 am

Saturn's rings

Cool image time! The image on the right, reduced in resolution to post here, shows how, because of the seasonal tilt of Saturn, the shadow of its rings is now cover much of the gas giant’s southern hemisphere.

When NASA’s Cassini spacecraft arrived at Saturn 12 years ago, the shadows of the rings lay far to the north on the planet. As the mission progressed and seasons turned on the slow-orbiting giant, equinox arrived and the shadows of the rings became a thin line at the equator. This view looks toward the sunlit side of the rings from about 16 degrees above the ring plane. The image was taken in red light with the Cassini spacecraft wide-angle camera on March 19, 2016.

We will continue to get from Cassini increasingly beautiful images of Saturn and its rings as the spacecraft positions itself better for its final flight down into the planet’s atmosphere.

0 comments

New model for Enceladus’s subsurface ocean

4:03 pm

A new model proposes that the subsurface liquid water ocean of Saturn’s moon Enceladus is possible only 3 miles below the surface near its south pole.

In order to reconcile the different constraints [created by the known data], the researchers propose a new model in which the top two hundred meters of the ice shell acts like an elastic shell. According to this study, Enceladus is made up successively of a rocky core with a radius of 185 km, and an internal ocean approximately 45 km deep, isolated from the surface by an ice shell with a mean thickness of around 20 km, except at the south pole where it is thought to be less than 5 km thick. In this model, the ocean beneath the ice makes up 40% of the total volume of the moon, while its salt content is estimated to be similar to that of Earth’s oceans.

Need I mention that this is only a computer model, and should therefore be considered with great skepticism?

Posted from warm and dry Tucson, Arizona, where I am home at last!

1 comment

Titan over Saturn’s rings

9:35 am

Titan over Saturn's rings

Cool image time! The picture on the right, taken on January 26, 2016 by Cassini and reduced and cropped to show here, captures Titan above Saturn’s rings, which are themselves partly obscured by the shadow of Saturn (unseen on the right) that falls across them.

Make sure you go to look at the full image. This is the kind of vista that artists in the 1950s imagined we’d see once we began to explore the solar system.

0 comments

Saturn’s moon Epimetheus

9:14 am

Epimetheus

Cool image time! The picture on the right was taken by Cassini on December 6, 2015, and shows the asteroid-like misshapen moon, too small (only 70 miles across) for gravity to force it into a sphere. Behind it, filling the frame, is gigantic Saturn.

If you look close, you can see one crater that appears elongated, as if the impact was only a glancing blow.

1 comment

The methane seas of Titan

10:23 am

Scientists have used the data that Cassini has gathered in more than a hundred fly-bys of Titan to assemble a rough outline of the geology and make-up of Titan’s liquid lakes.

There are three large seas, all close to the north pole, surrounded by dozens of smaller lakes in the northern hemisphere. Just one lake has been found in the southern hemisphere. The exact make-up of these liquid reservoirs remained elusive until recently. A new study using scans from Cassini’s radar during flybys of Titan between 2007 and 2015 confirms that one of the largest seas on the moon, Ligeia Mare, is mostly liquid methane.

“We expected to find that Ligeia Mare would be mostly ethane, which is produced in abundance in the atmosphere when sunlight breaks methane molecules apart,” explains Alice Le Gall from the Laboratoire Atmosphères, Milieux, Observations Spatiales and Université Versailles Saint-Quentin, France, and lead author of the new study. “Instead, this sea is predominantly made of pure methane.”

The data is also giving them the first understanding of the weather and geology that forms the lakes, including why methane instead of ethane dominates.

0 comments

Titan’s changing shorelines

8:53 am

Shoreline changes on Titan

Cool image time! Using radar images taken during the past decade by Cassini scientists have discovered changes taking place along the shorelines of Titan’s hydrocarbon seas.

Analysis by Cassini scientists indicates that the bright features, informally known as the “magic island,” are a phenomenon that changes over time. They conclude that the brightening is due to either waves, solids at or beneath the surface or bubbles, with waves thought to be the most likely explanation. They think tides, sea level and seafloor changes are unlikely to be responsible for the brightening.

The images in the column at left show the same region of Ligeia Mare as seen by Cassini’s radar during flybys in (from top to bottom) 2007, 2013, 2014 and 2015.

These shoreline changes are not the only ones spotted by Cassini. However, because these are radar images, not visual, there are many uncertainties about what causes the changes, which is why they list several possibilities. For example, with radar, a simple roughness on the surface (such as waves) could cause a brightening.

1 comment

Mighty Saturn

11:15 am

Saturn

Cool image time! Be sure to click on this link to see the full resolution Cassini version of the image on the right. Its resolution is 10 miles per pixel, and even so the giant planet cannot be fit in the frame.

One moon, Tethys, is visible, though to make it so required its brightness to be increased by 2. Also, if you look close at the bands at the north pole you can see their strange still-not-understood pentagon shape.

0 comments

The jets of Enceladus

9:09 am

Enceladus's jets

Cool image time! The image above, taken in June by Cassini, shows the night side of Saturn’s moon Enceladus, framed by Saturn’s rings, and faintly showing the jets of water coming from its south pole. To show it here I have cropped it and reduced it somewhat, as well as brightened the jets to make them more visible.

The release notes how the image compares the frozen water of Saturn’s rings and the liquid activity of Enceladus’s jets. I note how the image is simply beautiful. Be sure to click on the link to see the full resolution image.

1 comment

An Enceladus close look

11:28 pm

Enceladus at 77 miles

Cool image time! The image on the right is the first processed close-up image released from Cassini’s fly-by of Saturn’s moon Enceladus on Wednesday. The resolution is about 50 feet per pixel, taken from about 77 miles away. This surface, in the general area where Enceladus vents lie, reminds me of a thick field of snow that has begun to melt away.

Since the fly-by got within 30 miles, even higher resolution images should follow.

1 comment

Enceladus flyby images begin arriving

10:38 am

Enceladus

Cool image time! The first images from Cassini’s close flyby of Saturn’s moon Enceladus on Wednesday have started to arrive.

None have yet been processed, though the press release above provided a distant view of the moon’s plumes as the spacecraft approached. The image on the right, showing the moon itself, is one of the flyby I pulled off from the raw image website. Expect some interesting views to appear there throughout the day, with a more detailed press release tomorrow.

1 comment

Fractures on Enceladus’s north pole

6:02 pm

Enceladus's North Pole

The Cassini science team has released the first image from Wednesday’s flyby of the Saturn moon Enceladus.

Scientists expected the north polar region of Enceladus to be heavily cratered, based on low-resolution images from the Voyager mission, but the new high-resolution Cassini images show a landscape of stark contrasts. “The northern regions are crisscrossed by a spidery network of gossamer-thin cracks that slice through the craters,” said Paul Helfenstein, a member of the Cassini imaging team at Cornell University, Ithaca, New York. “These thin cracks are ubiquitous on Enceladus, and now we see that they extend across the northern terrains as well.”

To see more you can browse the raw images here.

The next flyby later this month will be especially interesting as they will dip to within 30 miles of the surface.

0 comments

New global maps of Titan

11:23 am

Titan's North Pole

The Cassini science team has released new maps of Titan, including new maps of both poles, assembled from images taken during the 100 flybys that the spacecraft has made of the moon since it arrived in orbit around Saturn.

The scale is rough, just less than a mile at best, and there is no topographic information because the thick atmosphere allows for no strong sunlight or shadows. The images show differences in surface brightness, which does tell us where Titan’s dark methane lakes are.

This is likely the best we will get of Titan for decades, until another spacecraft is sent there.

0 comments

Cassini’s last flybys of Enceladus

2:04 pm

As Cassini approaches the end of its decade-long mission at Saturn it will begin its last series of flybys of the moon Enceladus starting October 14.

Images will arrive a day or two afterward. The last two flybys will take place in late October and then in December, with the second October flyby getting closest, only 30 miles from the surface.

Beginning next year they will shift the spacecraft’s orbit so that it can get a better look at Saturn’s poles during its last two years. In that orbit flybys of the moons cannot be done.

0 comments
1 … 5 6 7 8 9 … 12