Giant Hurricane at Saturn's North Pole

Astronomers working with the Cassini spacecraft orbiting Saturn have taken a wonderful close-up picture in visible light of a giant storm at the exact North Pole of Saturn. On the FALSE COLOR image here, you can see the hurricane in red color right in the center. This giant storm is about 1250 miles wide (roughly 20 times the size of the eye of a typical earthly hurricane). Like sodas in the movie theaters, weather on the giant planets like Jupiter and Saturn comes only in super sizes .

(To be fair, this is not the first time we are seeing this storm. But now that summer sunlight is reaching the north pole of Saturn, we can actually see the storm in greater detail in visible light.)

Wind speeds at the edge of the storm are being measured at 330 miles per hour, so hold on to your hat if you intend to go windsurfing there.

Also on the current picture, in pale greenish color, you can see the mysterious hexagon of flowing gas that surrounds Saturn's north pole. This hexagon is about twice the size of planet Earth in diameter! The strange shape of this "jet-stream-like" feature is thought to be the result of complicated waves colliding in the upper atmosphere of the ringed planet.

Another storm is visible in teal color at the lower right, and -- in this false color view -- the rings of Saturn are an intense blue color in the upper right. (You can see the many ringlets that make up the rings. Bear in mind that each ringlet is composed of millions of chunks of ice, all staying in a regular traffic pattern around the equator of Saturn.)

Why is the image presented in false color? I think the Cassini astronomers themselves will be the first to tell you they make such images in part because they are beautiful. But also, in this case, color gives a sense of how high in the atmosphere you are looking. The reddish features are deeper down and the greenish ones float higher up.

Want to see the hurricane move? There is a wonderful short movie with good narration by astronomer Andrew Ingersoll that has been assembled at:http://photojournal.jpl.nasa.gov/archive/PIA14944_640.mov
(You will need the free Quicktime player on your computer to see it and a little time for it to load.)

For readers who are more technically oriented, a nice discussion of a possible explanation for why the jet stream takes the shape of a hexagon can be found in one of Emily Lakdawalla's columns at: http://www.planetary.org/blogs/emily-lakdawalla/2010/2471.html

New Hubble Image of Giant Star Nursery

The Hubble Space Telescope folks have just released a beautiful photo of a region where new stars are forming. Called by its catalog number, N11, this region of young stars and reddish glowing gas is in the Large Magellanic Cloud, one of the satellite galaxies that goes around our Milky Way. When you look at the image, bear in mind that the light we are seeing today from this galaxy left it 168,000 years ago. (In other words, the photo shows something 168,000 light years away.)

In the upper left corner, you can see the Rose Nebula, a tight round region in whose hidden center, new stars are being born right now. To give you a sense of scale, that little round gas cloud -- at the very top right -- is about 8 light years across.

In the middle of the image is the more extensive cloud of gas and young stars nicknamed the Bean Nebula (because of its shape.) Several generations of stars have been born in that cloudy region, and their adolescent energy has helped push the gas that gave birth to them into a larger and larger region.

Toward the bottom of the picture, you can see a jewel box of young bluish stars. Many are so hot they actually glow not just with blue and violet light, but with ultraviolet (what tanners call "black light.") Their energy has pushed for a while on any remaining gas from the cloud that gave them birth, so the neighborhood around them shows almost nothing of the reddish glow that signals warmer gas.

N11 is one of the largest nurseries for making stars we have ever observed. It's wonderful to have such a clear colorful image of the whole area, thanks to the remarkable instruments aboard the Hubble.

(And a personal note: the catalog number N11 is from a list of such glowing nebulae first put together in the 1950's by astronomer Karl Henize. Later in life, Henize became a Shuttle astronaut, and when it was his turn to go to space, he was a member of the Board of Directors of the Astronomical Society of the Pacific, where I was the Executive Director. He found that he had enough room in his personal kit to take a banner for the Society into space with him. We didn't have a banner, but when he offered, we of course made one up, real fast. He brought it back from space and presented it to me in a wonderful ceremony at the Society's headquarters (see photo below). It still has a place of pride on the walls of the Society's building in San Francisco.)