A Great New Image of Saturn

NASA has recently released a spectacular new image of the planet Saturn, seen when it's summer in the Northern Hemisphere. (A year on Saturn is about 30 Earth years, so each season there lasts about 7.5 of our years! Saying goodbye for summer vacation is a big deal there.)

The rings are seen in fine detail with the shadow of the planet toward the left side. The mysterious hexagon-shaped storm at the north pole is also clearly visible. You are seeing Saturn from a distance of about 1.9 million miles.

The image was taken with the Cassini spacecraft that has orbited Saturn and shown us the planet, its rings, and its fantastic moons since 2004.

Enjoy. (Click on the image to see it bigger.)

An Amazing Image of Saturn's Rings for the Holidays

Carolyn Porco, the dynamic leader of the Imaging Team for the Cassini Mission (exploring Saturn and its neighborhood), has sent a remarkable holiday greeting card from Saturn and I wanted to share it with you.

What we are looking at is a view of the inner part of Saturn's complicated ring system (mainly the so-called B ring.) We are seeing about 750 miles of the white rim of the B ring, beyond which is the dark emptier space called the Cassini Division. You can see a number of thin "ringlets" in that division toward the upper part of our picture.

But what is really stunning is what the long shadows cast by the Sun reveal at the edge of the bright main ring. You can see peaks or thin mountains of ice particles, sticking up more than a mile and a half (2 km) above the plane of the rings. Compare those heights with the typical height of the ring system, which is about 10 meters (or about 30 feet) in most places.

Here is what Carolyn says about the image, "Cassini scientists believe that this is one prominent region at the outer edge of the B ring where large bodies, or moonlets, up to a kilometer or more in size, are found. It is possible that these bodies significantly affect the ring material streaming past them, and force the particles upward, in a "splashing" manner."

She continues, "This image [taken in 2009] and others like it are only possible around the time of Saturn's equinox, which occurs every half-Saturn-year, or about every 15 Earth years. The illumination geometry that accompanies equinox lowers the sun's angle to the ring plane and causes structures jutting out of the plane to cast long shadows across the rings."

The rings of Saturn are made of billions and billions (as Carl Sagan used to say) of individual chunks of ice -- mostly water ice. The particles range in size from smaller than a sand grain to larger than a modern SUV. We have known for some time that the interaction of moons and rings in the Saturn system can create a wide range of artistic patterns using the ring particles as their raw materials. But these tall icicles or icy towers are among the most spectacular we have ever seen.

Happy Holidays. May 2015 bring all of us more amazing views of our cosmic environment and increase our understanding that the differences that separate us on Earth are so trivial compared to the truly alien nature of what's out there.

[Click on the image to make it bigger and see even more detail!]

A Dark Spot on the Sun Seething with Energy

Many of you in North America who saw the partial eclipse of the Sun last Thursday may have noticed a nice dark spot under the eclipsed part of the Sun.  The full "active region" (that the visible spot is part of) is bigger in area than the giant planet Jupiter and has become the largest such feature on the Sun in 24 years.

With the kind permission of the photographers, I am posting here a beautiful close-up of the area, by Randall Shivak and Alan Friedman.  Look how wonderfully complex it is!

The darker regions on the Sun are called sunspots; they look darker because they are slightly cooler than the Sun's visible surface layer. The Sun is made entirely of seething hot gas, where the atoms are so hot, they easily lose their electrons.  This makes our Sun highly magnetic, and as it spins, its magnetic zones get all twisted up.  It's those twisted regions that appear to us as active regions.

Astronomers have already observed some "flares" -- sudden releases of extra energy -- from this region, but they haven't been sent in our direction in space.  The region is now facing the Earth as our Sun does its slow rotation.  So we may get some extra high -energy particles coming our way in days to come (or not -- weather from the Sun is as hard to predict as weather on Earth.)

For a nice movie of this region "crackling" with magnetic energy as the Sun rotates, see: http://apod.nasa.gov/apod/ap141022.html

A Beautiful Image with a Nice Ring To It

Here is a dramatic image of a dying star, courtesy of amateur astronomer and master photographer Robert Gendler. Called the "Ring Nebula," this cloud of of expelled material surrounds a star somewhat like our Sun, but further along in its life cycle.

Usually, regular telescopes only show the inner glowing part that you see in bluish green in the center. But Dr. Gendler has combined the visible-light image with fainter, cooler infra-red information to show how the star has expelled material not just once, but many times. You can see shell after shell surrounding the star. Like a dying man in those old Victorian novels, who coughs and coughs for months before death releases him, this star has been "coughing up" its outermost layers, as it adjusts to the final internal collapse. After the expanding shells have moved away, what will be left is a dense, hot "star corpse" astronomers call a white dwarf.

The image pixels come from the Hubble, Subaru, and Large Binocular Telescopes. By all means click on the picture and look at the larger version.

The Ring Nebula (a favorite astronomical object for newlyweds) is about 2000 lightyears away in the constellation of Lyra. It is perhaps the best known example of a "planetary nebula." (The name comes from their fuzzy appearance in early telescope; the expanding shell of gas has NOTHING to do with planets.) Astronomers also call it M57 (the 57th entry in Charles Messier's catalog of fuzzy objects in the sky.) If you search for M57 on the web you can learn a lot more about it; or just enjoy the weirdly wonderful picture.

Robert Gendler's other astronomy images can be found at: http://www.robgendlerastropics.com/  

To see a larger version of the amazing Hubble Space Telescope image of this object (which is at the center of our picture), go to: http://hubblesite.org/newscenter/archive/releases/2013/13/image/b/format/large_web/ 

An Eerie Astronomical Photo

Click on the photo to make it bigger ^

Here is a gorgeous image taken by master astro-photographer Travis Rector (of the University of Alaska), showing a region of cosmic raw material (glowing gas and dark dust.) This is like one of those inkblot tests that psychologists are fond of -- what shape you see in the picture may be highly individual.

What we are actually looking at is a small part of a larger region where star birth is going on right now. Known by its catalog number of IC1396, this "emission nebula" is set to glow by the brilliant light of new stars that have already been born in this region and are shining with adolescent energy.

IC1396 is a cloud of loose gas and dark dust (the dust really isn't that different from what you find under your desk when you are too busy thinking cosmic thoughts to clean up regularly.) The dust is shaped into long filaments, when the light of energetic stars pushes the less dense parts of the dust away from the stars (in this case, in the down direction on this photo.) Only the thickest regions of dust remain after a while, making long, dark tendrils like we see here.

IC 1396 is about 3000 light years away in the constellation of Cepheus. You can see the entire nebula (much larger than the small part seen in our photo) here:
http://apod.nasa.gov/apod/ap120805.html

So what did the dark shape remind YOU of?

Gorgeous Picture of Saturn from Above

Today, I just want to share a beautiful image with you. This view of planet Saturn, seen from above by the Cassini spacecraft was assembled from a variety of close-up images by computer programmer and amateur image processor Gordan Ugarkovic, but released by NASA because they were so pleased with the result.

Here we are looking down on the North Pole of Saturn in October 2013 (the weird weather feature called the "Hexagon" is faintly visible around the pole.) Such a perspective is not possible from Earth, but only from a spacecraft like Cassini.

The Sun is off to the left in this picture, and we see the planet casting a dark shadow on its own rings.  The bands of "stormy weather" at different latitudes are also visible. Saturn is a planet made mainly of gas and liquid. If you were to try to "land" on Saturn, you wouldn't -- you'd just sink in and in.

You can see Saturn's main ring system surrounding the planet's equator. To give you a sense of scale, if we were to put Saturn down next to the Earth, the ring system would stretch almost from the Earth to the Moon. Click on the photo to see it bigger and enjoy!

You can see more of Gordan's home processed Saturn photos at:http://www.flickr.com/photos/ugordan/sets/72157594305165539/

A Beautiful New Image from the Hubble Telescope

Here is a gorgeous picture of a spiral galaxy, which is part of the Coma Cluster of galaxies, roughly 300 million light years away. This galaxy (of billions of stars), like our own, is shaped like a frisbee -- and we are looking at the disk of the frisbee face-on. Its name is just a catalog number: NGC 4921. You can see its huge encircling "arms" of countless stars, blending their light together. And notice a number of clusters of young stars glowing blue, a little distance out from the center.

But what is amazing about this image, if you look at it for a while, is how many OTHER galaxies are visible through and around NGC 4921! All those structures around the galaxy that are not precise pinpoints of light are other great islands of stars -- each containing billions of stars and planets. The cluster of galaxies which NGC 4921 is part of contains more than a thousand galaxies. And there are more galaxies beyond that cluster. Pictures like this help us remember that our problems and disagreements on Earth are such minor issues when seen from the perspective of the universe.

This image, by the way, was assembled from a number of Hubble Space Telescope images and processed by Roberto Colombari, an Italian astronomical photographer working in Brazil.

As the World Turns

It's a dizzying thought, but the solid ground beneath our feet is moving at great speeds through space. For example, our planet turns once a day. Every 24 hours, the place where you live on the surface of the Earth goes in a big circle around the center of our planet. In the San Francisco Bay Area, this motion happens at a speed of about 818 mph. (Children, you can do this without adult supervision, because gravity holds all of us firmly to the Earth's surface.)

Our planet turns around an imaginary stick that goes from the Earth's north pole through its south pole. We call the line of that imaginary stick the Earth's "axis." As our planet turns around its axis, the Sun appears to rise in the East and set in the West and we have day and night. At night, as we turn, we see everything in space slowly turning around us. But we know the Sun during the day and the stars at night are not really turning. They sit in space and mind their own business. The motions we see in the sky hour by hour just reflect the turning of planet Earth. Do you want to see this motion displayed?

On the magnificent photo I have attached to this little posting, you can actually see the turning of the stars (around the still point of the north pole of the sky). Master photographer Phil McGrew captured the turning of the sky above the Golden Gate Bridge. I was so enchanted with this photo, I asked him to give me permission to share it with all of you. You can see more of his photos at his web site: http://www.philmcgrew.com/

The photo is actually made up of more than 180 20-second exposures, skillfully added together. Instead of being a point, each star becomes a curved line as the Earth turns with the camera and photographer attached to it. Astronomers call the curved lines "star trails."

Can you think of other ways that you are moving even while sitting still in your favorite armchair? We'll discuss these other motions in future posts.

Stunning Wide-Field Image of a Star Nursery

Every once in a while, I see a new astronomical picture that leaves me with my mouth open, saying "Wow!" The above image, assembled by a talented amateur astronomer, from information taken by a number of different telescopes, is one of those.

This wide-angle view is centered on a cluster of recently-born stars that is known by its catalog number of NGC 2264. Surrounding the adolescent stars is a whole region of cosmic gas and dust -- the raw material from which stars are born. The nearby gas glows with the characteristic red color of its most common constituent -- hydrogen.

At left center is the Cone Nebula, a region of gas and dust in the shape of a sideways dark cone; the energy of bright stars to the right of the cone is eating away at the sides of this thick dusty region, leaving only a cone of thicker material behind.

To the right of the Cone Nebula, you can see an opposite (larger) cone pattern of bright stars stretching rightward. Some people see the lights of a sideways holiday tree in the pattern of bright stars.

At the bottom center of the image, pointing upward into the bluish emptier region (where the energy of freshly made stars is clearing things out), you can see an odd region of gas and dust that is sometimes called "The Fox Fur Nebula." Click on the picture and take a good look -- can you see the head of a furry red fox pointing upward into the bluish region?

The entire complex of stars and gas and dust is about 2,600 lightyears away, which means the light we see tonight left this region about 2,600 years ago -- a time when humans on Earth lived a much more challenging existence and lifespans were less than half of what we enjoy today.

This remarkable picture was assembled by Dr. Robert Gendler, a physician and amateur astronomer, who is a master at working with photographic information using his computer. The image was constructed from information provided by the Subaru Telescope in Japan and the Digitized Sky Survey, put together by astronomers at the Space Telescope Science Institute from a number of earlier surveys of the sky. To see more information about the photo, see:
http://www.robgendlerastropics.com/Cone-Subaru-DSS.html

You can go to Dr. Gendler's home page at that site and then browse his many other wonderful images. But take a minute and just enjoy a full-screen version of the picture -- you are seeing the same process of star birth that gave rise to our Sun some five billion years ago.

Making Yourself at Home on Mars

One of the most interesting results of NASA's policy to make its planetary images widely and freely available is that talented photographers around the world have combined and extended the photos to make clearer or wider views of what it's like to be on another world.

A wonderful example can be found at a site for panoramic (360-degree) images, where photographer Andrew Bodrov has made one of the most exciting space images I have yet seen:
http://www.360cities.net/image/mars-gigapixel-panorama-curiosity-solar-days-136-149#-410.49,13.54,42.5

Bodrov stitched together 407 different images from two different cameras aboard the Curiosity rover on the red planet Mars. You can see the rover itself and the "Yellowknife Bay" neighborhood that it was exploring at the time that it did the first experiment drilling into a Mars rock. The large mountain in the distance is Mt. Sharp, the rover's ultimate destination.

I encourage you to play with the image for a while. There are controls at the upper left to help you move around and your cursor also gives you control of the speed and direction with which you move through this rich image. Enjoy the details of the rover's machinery and the wide range of rock formations around the little robot visitor.

A Gorgeous Galaxy Like our Own

We live in an enormous "island" of stars called the Milky Way galaxy -- a collection of over 200 billion stars (and probably billions of planets). Since we are inside the Milky Way, it's hard to take a complete picture of it. It's like trying to take a picture of yourself from inside your gall bladder -- the view is not too clear. But we can learn about our own galaxy by observing others that are like us in size and shape.

In this beautiful picture, assembled from a Hubble Space Telescope image, as well as color information from a Japanese telescope and other observers, you can see a near cousin of the Milky Way located at a distance of about 50 million lightyears. (That means the light from this great "city of stars" took 50 million years to reach us!)

This galaxy doesn't have a name (like most galaxies), but simply referred to by a catalog number -- NGC 7331. Like our Milky Way, it is a spiral-shaped assemblage of stars and cosmic gas and dust. It contains about the same amount of material as our galaxy. We see it tilted to our line of sight, accounting for its oval (rather than circular) appearance.

It appears from other observations that NGC 7331 has a giant black hole at the center that has swallowed much more material than the black hole at the heart of the Milky Way. We are no longer surprised when we find giant black holes at the cores of galaxies -- it appears most grown-up galaxies have them.

Above and to the left of NGC 7331 are two other galaxies, which are about 10 times farther away! They just happen to be in the frame of the picture, like movie extras behind the actor whom our attention is focused on. Billions upon billions of galaxies make up the observable universe.

This gorgeous picture was assembled from different sources by Dr. Robert Gendler, a physician on the East Coast, whose passion is astronomical photography and whose skill at computer rendering of our skies is extra-ordinary. As many students and teachers travel or rest for spring vacation around this time of year, here is a celestial tourist sight for your enjoyment.

An Amazing Picture of an Active Galaxy by the Hubble and an Amateur Astronomer

This past week, the scientists at the Space Telescope Science Institute released a remarkable picture, which combines Hubble images with those taken by advanced amateur astronomers on Earth, and I'm glad to be able to share it with you.   (Click on the picture to make it bigger.)

In the image, we're seeing the central part of an "active" or disturbed galaxy about 25 million light years away, with the catalog number M106.  You can see the yellow center of the galaxy, crowded with stars whose light blends together.  You can also see its great spiral arms of stars, gently curving away from that center.  They are outlined with blue stars and regions where gas is being heated by stars and glowing red.  Those arms go much further out than the boundaries of this picture.  

But what is especially interesting is that there are also great jets of glowing red gas, which are not part of the flat spiral structure of the galaxy.  Instead, they are at odd angles to the galaxy's disk.  What we are seeing there are great clouds of glowing hydrogen -- the most common element in all galaxies.  But what makes them glow so intensely?  Astronomers have good evidence that they are energized by radiation (not visible to the human eye) coming from a super-giant black hole at the center of the galaxy.  

Neither the black hole (somewhere in the middle of the yellow center) or its rays of energy are visible here.  But when those rays hit the gas that is the "raw material" of such galaxies, they make it glow with a fierce intensity.  

This beautiful photograph was assembled by an amateur astronomer, Robert Gendler, a doctor living on the East Coast, who has made astronomical photography his hobby and his passion.  It's quite a coup to have his photograph used and released by the Hubble scientists.  For more of Dr. Gendler's photos, see his web site at: http://www.robgendlerastropics.com/

If you want to learn some basic information about black holes, you can check out a little video of a 6-minute talk I gave about them at the SETI Institute: http://www.youtube.com/watch?v=7DX_cc-IjpY 

Amateur astrophotographer R. Jay Gabany also contributed to the image.  You can see his image (with less detail) but showing the whole galaxy and really emphasizing the gas excited by the black hole at:
http://apod.nasa.gov/apod/image/1103/lrg_ngc4258gabany.jpg