New Hubble Image of Jupiter's Red Spot

Astronomers are eagerly awaiting new information about the Great Red Spot, the largest and most colorful storm in the atmosphere of the giant planet Jupiter. The Juno spacecraft just flew as close as 5600 miles over the Red Spot, and the information is coming slowly back to Earth. This giant storm is currently about 10,000 miles wide -- larger than the entire planet Earth -- although it is smaller than when the Voyager spacecraft flew by in the 1970's. Why it has been shrinking and why it's color is so vivid are mysteries planetary scientists are trying to solve. 

In the meantime please enjoy the attached Hubble Space Telescope image of Jupiter, taken on April 3, when the Earth was closest to Jupiter in its yearly orbit. The Red Spot is vividly clear on this wonderfully detailed image, taken from just a few hundred miles above our planet's surface.  (Click on the image to see it bigger.)

New Views of the Planet Jupiter

The first results are in from the Juno mission exploring the giant planet Jupiter, and there are many surprises.

Look at the beautiful image here (click on it to see it bigger), showing the first detailed views of Jupiter's south pole region. The colors are a bit exaggerated, but the structures are real. You are seeing giant cyclones and anti-cyclones, as large as 600 miles across! That's extreme weather the 11 o'clock news team doesn't even dream about.

I'll remind you that Jupiter is not a solid planet -- most of it is made of gas and liquid. Yet there is enough material inside the giant planet to make 318 Earths. Scientists did not know whether at its very center it might have a small solid core or not. Heat from within rises and various molecules move up and down, producing complex bands, zones, and storms in the upper atmosphere.

Additional Juno discoveries include that Jupiter has a bigger core than expected, but that it has a fuzzy-looking structure, as if it were not sharply defined. The giant magnet inside Jupiter that surrounds it with the most powerful magnetic zone of any planet was also found to be stronger than anticipated.

Furthermore, the northern and southern lights on Jupiter are excited not only by charged particles captured from space (as we have on Earth) but also, unexpectedly, from charged particles coming from inside Jupiter.

As usual, when we get better instruments focused on a world or process in astronomy, we find that some of our old assumptions or ideas will need to be revised. That's what makes astronomy so much fun.

Below is an image showing 14 days of the Juno spacecraft approaching and then moving further away from Jupiter's cloudy atmosphere. (Click on it to make it bigger.)

A Weird-looking Moon in a Gap in Saturn's Rings

Since 2004, the sophisticated Cassini spacecraft has been orbiting Saturn, sending back remarkable pictures of the planet, its rings, and its moons.   Now, with its fuel running out, the little spacecraft is being directed closer to Saturn’s rings, to get us even better views of this spectacular region (before Cassini does a Kamikaze dive into Saturn Sept. 15th.)

The image above is a fantastic close-up of one of the strangest moons we have ever seen.  The small moon Pan orbits inside the Encke Gap, an emptier region in Saturn’s bright A ring (Saturn’s different rings are given letter names.)  Pan looks like a “flying saucer” – with a set of high ridges around its equator.  It's about 22 miles across at its widest point.

Astronomers think that Pan formed inside Saturn’s ring and, as it grew, its gravity helped clear out the material in the gap which it now rules.  But there was enough material still in the flat ring neighborhood that it fell onto Pan’s equator and made the giant ridges that make Pan so distinctive.

Over the next few months, as scientist program Cassini to dive again and again into the space between Saturn’s and its rings, we will continue to get better images of “things in the rings” (sounds like Dr. Seuss) than we ever have before.  It’s a fitting finale for a spectacular space mission.

The image below shows you the neighborhood.  You can see Pan, its shadow, the Encke gap, and the A ring.  

A Tight Little Planet System, Dancing to the Tune of Gravity

Careful measurements using information from the Kepler planet-hunting spacecraft has allowed astronomers to figure out one of the tightest and most synchronized planet systems ever found.

Kepler 80 is a dim star in the constellation of Cygnus the swan, 1100 light years away, that has five planets orbiting it. That by itself is not unusual -- astronomers have now discovered a number of stars with 7, 6, or 5 planets around them and more are likely to be discovered as time goes by. What IS unusual is how tightly these five planets all hug their star.

The five planets take one, three, four, seven and nine earth days to orbit the star. (Think about that, their year is 1, 3, 4, 7, or 9 DAYS! If you lived on the inner planet, you would be 365 of its years old after one Earth year had gone by.)

Even more interesting, the outer 4 planets have orbits that are synchronized -- they are in tune, you might say. They return to the same arrangement of their positions around their star every 27 days. This is called a gravitational resonance and it's something gravity prefers to do when bodies can exchange energy.

Think of gravity like your uncle who is careful with his money -- they both prefer arrangements that are cheap! For example, gravity, when it can, tries to make bodies round, because then the pull on every point on the surface is the same -- which is the arrangement that takes the least energy.

When objects in space move around or with each other in a synchronized way, where one orbit is related to the other with numbers like 1 to 2 or 2 to 3, this requires less energy too. Pluto, for example, shows an extreme example of such resonances: Pluto takes 6.4 Earth days to spin and Pluto's big moon Charon takes 6.4 days to orbit the dwarf planet. So Pluto's day and month are the same length. Charon also takes 6.4 days to spin, so we have a 1 to 1 to 1 resonance of these motions.

Calculations show that the planets dancing in resonance around Kepler 80 are rocky world like our own Earth, although at least some of its planets are 4 to 6 times Earth's size. Imagine these giant Earths whipping around that little star in Cygnus in 1 to 9 days, year in and year out, lining up every 27 days in a kind of cosmic dance. Nature seems to permit so many odd and wonderful line-ups of planets out there -- science fiction is having trouble catching up to science fact.

(Just for comparison, the innermost planet in our own planetary system, Mercury, takes 88 days to orbit the Sun, and it is much smaller than Earth. So we have no large planets tightly hugging our star -- but a number of other stars besides Kepler 80 show such tight arrangements.)

Pluto Has a Crazy Tumbling Moon (Great Video)

Pluto has five moons around it and one of them, it was reported today, spins 89 times for each orbit it makes around Pluto. Hydra, the outermost of Pluto's four tiny moons, takes 38 Earth days to go once around the dwarf planet. During that time, it rotates 89 times.

For a hypnotic video of the motion of all the moons, see:http://www.seti.org/…/defau…/files/dps-slides-showalter1.mp4

(Note that on the video, the moons are not to scale. In real life, the outer 4 moons are much much smaller than Pluto and the giant inner moon Charon, which is about half of Pluto's size. But the motion you see on the video is real.)

Hydra is the purple object on the video. The moon colored yellow, called Nix, spins almost fourteen times during one of its orbits. (The colors mean nothing on the video; they just help our eyes tell the moons apart.)

Astronomer Mark Showalter of the SETI Institute, who discovered two of the moons, is part of a team that suspects that the tumbling of the moons is caused by the extra pull that the giant moon Charon adds to the pull of Pluto in this system.

Another interesting fact about the motions in the Pluto system is that Pluto's day is equal to Charon's month.  In other words, Pluto rotates at the same rate as its giant moon orbits it.  That means Pluto and Charon are synchronized -- one side of Pluto always has Charon above it as it turns, and the other side of Pluto never sees Charon.  

By the way, it also appears from the New Horizons data coming back to Earth that Hydra and Kerberos (the green colored moon) are each made of two smaller chunks of ice that "merged" into one close system early in Pluto's history. Perhaps all four of the small moons are the result of such mergers. So here are two chunks of cosmic material living together intimately for billions of years. Perhaps the Tea Party fundamentalists and Supreme Court Justice Scalia might not approve of such a "marriage" between icy chunks, but I think it's pretty cool.

My First Science Fiction Story Published

As some of you know, I have long enjoyed science fiction, both as fascinating reading and also as a nice addition to my introductory astronomy classes. For 30 years, I also kept a diary of science fiction ideas that occurred to me, and might make the basis of good stories.

In the last year or two, I have joined a writing group and am trying to create some SF short stories of my own. I have a full bulletin board of eloquent rejection slips from some of the finest science fiction magazines in print (as, I gather, all beginning writers must collect,) But now, one of my stories has been published, in a Mars-theme anthology called "Building Red," from a small independent press in St. Louis called Walrus Publishing (and the book is available on Amazon: http://www.amazon.com/Mission-Mars-Building-Ja…/…/1940442079 )

The story, based on a real discovery about Mars, takes place in part inside a cave on the flanks of one of the four giant volcanoes on Mars' equatorial bulge. Instead of the sanitized, squeaky-clean NASA version of a future Mars colony, I tried to imagine one that's crowded, smelly, and has its share of loners and misfits.

The story is entitled "The Cave in Arsia Mons" and it appears together with Mars stories by a number of writers, some of whom have a longer publishing record in SF than I do.

More generally, for a topical index to science fiction stories that have good astronomy in them, see my web page at: 

http://www.astrosociety.org/scifi 

Blue Skies on Pluto

The New Horizons team just released a great new image of Pluto in front of the Sun. If Pluto had no atmosphere, it would just have blocked the Sun's light for the camera. But Pluto's thin (but significant) atmosphere scatters blue light more than red, just like Earth's air does, and so we can glimpse blue skies (or at least blue haze) around Pluto in the picture.

The haze layers in Pluto's atmosphere (seen more clearly in the black and white photo below) are made of slightly larger particles than Earth's haze layers, a kind of alien soot.

The lower image, showing Pluto at sunset, shows how the haze has several layers in it. The atmosphere is a thin mixture of nitrogen, carbon monoxide, and methane. Not a place where you want to (or can) take a deep breath! Astronomers think the atmosphere of Pluto is a bit thicker when it's closer to the Sun in its 250-year orbit, and then freezes out when it moves away from the distant sun for most of its plutonian year.

Also on the lower image, you can see the contrast between the mountainous higher lands on Pluto, and then in the middle of the picture, the smoother frozen plains that interrupt them. Only about 10% of the images and data have been sent back by New Horizons so far, so we have much more to learn about the little planet we visited briefly in July.

(As always, click on the photos, to see more detailed versions. Feel free to pass the pictures and information on, if you like them.)

New Pluto Images Reveal Glaciers Flowing from the Heart

New images released from the New Horizons spacecraft's encounter with Pluto reveal a reddish world, where water is as hard as rock, and substances that are gas on Earth have become ice glaciers. The beautiful color picture with this post shows you a section of Pluto that includes the heart-shaped feature named after Clyde Tombaugh, Pluto's discoverer. The left lobe (section) of the heart is being called the "Sputnik region," after the first satellite humanity ever sent into outer space.

Why is Pluto reddish? The team's first thought is that ultra-violet light from the Sun acts on the gases in the thin Pluto atmosphere -- methane (natural gas) in particular -- and breaks them apart and reforms them into more complicated combinations of hydrogen and carbon. Eventually, the molecules get so complex and heavy, they fall out of the air and coat the surface. Such hydrocarbons tend to be reddish when we see them on other worlds.

The New Horizons craft has only returned about 5% of the data it has stored in its memory, but even first results show haze layers in the Pluto atmosphere that support the notion of the air having chemical reactions going on, despite the cold.

If you look at the Heart in the picture, you can see that the left Sputnik region (which is about the size of Texas) has a thicker covering of ice than the right half of the Heart. Our black-and-white image shows a close-up about 250 miles wide in the northern part of Sputnik. At the top you see some of the older, cratered terrain that is above the Heart. But below that, the Heart itself is smooth and young-looking (no craters, which are a sign of age.)

The smooth ice we see is made of nitrogen, methane, and carbon monoxide, its top layers freezing out of the air when Pluto gets further from the Sun. (Pluto was closest to the Sun in its almost 250-year orbit in 1989, so we are just moving away from the time that Pluto is warmest.)

At Pluto temperatures, an ice made of nitrogen will very slowly flow, like a glacier flows across the landscape on Earth. The arrows on our black-and-white image show the direction scientists think the ice is flowing in Sputnik. At Friday's press conference, the experts said that their impression of Sputnik is that it's a very young region (geologically speaking) -- perhaps only tens of millions of years old. (For comparison, we think Pluto, like the rest of the solar system, is 4600 million years old.) Its glaciers have moved into any available regions next to Sputnik, and have filled valleys and craters on all sides.

Look also at the intriguing "polygon" patterns (many-sided figures) in the ice of Sputnik on our picture. They look like huge, geometric cells in the ice, perhaps half a mile or more deep. One possibility is that in these cells, hotter material from deeper inside is slowly rising, a process called "convection."

These images and ideas are just the (pardon the expression when discussing Pluto), just the tip of the iceberg. It will take 16 months for the full set of pictures and data to be sent back from New Horizons. Better images are expected in September, for example. Stay tuned.

In this last image, you see Pluto (left) and its large moon Charon in realistic color.  Such a dramatic pair at the outskirts of our solar system!

Getting Close-up with Pluto's Moon Charon

One of the most intriguing things about Pluto is that it is more of a double planet than a planet with moons. One of Pluto's moons, Charon (pronounced like Sharon or Karen; both are used) is half the size of Pluto. No other moon we know is this big compared to the planet it orbits -- just another way that the Pluto system operates outside the usual rulebooks.

The diameter of Charon has been measured to be 751 miles, about the size of Texas. Charon has settled into the most comfortable orbit around Pluto that nature permits. It rotates and revolves in 6.4 Earth days, which is also the rate at which Pluto turns. This means that the day on Pluto is the same length as the Charon month, which hurts your head if you try to think too much about it.

Now the New Horizons craft is starting to send back images of Charon as well, and again, we are surprised. Our photo shows a black and white global picture of Charon that has been tinted with actual color information from one of the other instruments. The New Horizons team is informally referring to the striking dark spot near the top of the image as "Mordor," much to the delight of fans of the Lord of the Rings trilogy.

But the inset in our picture is the most interesting. It shows an area of about 240 miles across (from top to bottom) and you can see some of the trenches and canyons that we are finding on Charon. Craters are also visible. Near the top left, we see a giant ice mountain sticking out of a trench. The NASA news release says: “This is a feature that has geologists stunned and stumped.” How did the mountain get or grow in there? It's those kind of odd mysteries that scientists live for.

(By the way, if you were asking yourself why the big moon has two different ways of pronouncing its name, it's a romantic story. The proper pronunciation from Greek mythology is like "Karen". But James Christy, the astronomer who discovered the big moon in 1978, secretly wanted the name to also remind people of his wife Charlene. So he likes making the name sound more like "Sharon." Astronomers (like most people) love romantic stories, so many use the pronunciation that Christy likes.

And Pluto itself has a name with a secret -- the astronomers at the Lowell observatory wanted to name it after their patron and founder, Percival Lowell, but we don't name planets after real people. So when a schoolgirl in England suggested the name Pluto to them, they jumped at it, since the first two letters are Lowell's initials.)

First Close-up Peek at Pluto's Surface

Here is the first detailed image of the surface of Pluto, released today, and it's already providing surprises. The yellow bar gives you a sense of scale; Pluto's diameter is 1473 miles (just measured by New Horizons), so we are seeing only a small part of it here.

The angular structures in the top half of the picture are mountains, the tallest being about 2 miles high. Most likely these mountains are made of frozen water -- it's so cold on Pluto that water becomes harder than rock. In fact, it is likely to be layers of "hard frozen water" that make up much of the surface of this distant world.

The biggest surprise is that the surface shows no craters, large or small. Craters are made on every world when chunks of rock or ice hit and carve out a circular depression. Since every world is regularly being hit by pieces of cosmic debris that fly through our solar system, any world without craters must have a way of erasing them pretty quickly after they form. Scientists are estimating that the absence of craters means that the surface of Pluto is being refreshed by some process, and can't be more than a hundred millions years old -- which is very YOUNG compared to the 4600 million year age of the solar system. What keeps the surface of this little world refreshed and erased is the first challenge Pluto has thrown in the face of the scientists eager to study it.

Where Would Bill Gates' Great Granddaughter Go for Her Honeymoon?

Imagine a future when space travel is common-place and you can visit the planets.  What will be the top tourist sights in our solar system?  (This is an activity I like to have my students think about as they get near the end of my introduction to the planets class.)

If you are an astronomy fan, play the game yourself. What would you pick for those once-in-a-lifetime sights that future travelers may want to visit and photograph on a honeymoon trip or graduation journey?  

For those of you who happen to be in Northern California on Saturday evening, June 20th, I will be revealing my favorites in a free public talk on Mt. Tamalpais just north of San Francisco.  (My first-ever outdoor lecture with slides!)

For those elsewhere, I'll give you a sample.  Some of my favorite stops include the 4,000-mile lava channel on Venus (always a good planet for a hot time), the towering Mount Olympus volcano on Mars (three times the height of Mount Everest), the awesome Verona Cliffs on the moon Miranda (which are the tallest “lover’s leap” in the solar system), and the recently discovered steam geysers on Saturn’s intriguing moon Enceladus (nicknamed “Cold Faithful.”)

After the lecture, there will be a laser-guided tour of the night sky by Paul Salazar and stargazing through the telescopes of the San Francisco Amateur Astronomers. This is an OUTDOOR venue, so we ask that people dress appropriately (it can get cold), and bring a flashlight to help find your way to and from the parking lots.

For more details, see: http://wonderfest.org/tourist-in-solar-system/ 

Admission is free, but seating is on a first-come, first-served basis. 

For maps and directions, see: http://friendsofmttam.org/astronomy/directions-and-contact-information.html

If it looks like rain, please call the Mt. Tam hotline at 415-455-5370, after 4 pm.  Since this is an outdoor event, it gets canceled if it is raining.

Our photo shows Saturn casting a shadow on its own sunlit rings in a view from the Cassini spacecraft.

Wonderful New Image of Comet We Are Flying Along With

The Rosetta spacecraft is continuing to circle Comet 67P (also known as Comet C-G) and send back amazing images. The picture accompanying this post was taken on Feb. 6 at a distance of 75 miles from the comet.

Rosetta, a mission by the European Space Agency, is flying along the icy chunk that is the comet, accompanying it on its long voyage to whip around the Sun. As we get closer, the ice of the comet will evaporate more and more, and great jets of gas will be seen coming from the comet. (Ice turns directly into gas in the vacuum of space.) You can see the beginning of this activity on our photo.

For the sake of honesty, we should mention that this 6-second image was processed to make the faint jets appear brighter and more easily visible.

We now know that the comet consists of two sections (called lobes, likes the two parts of your brain) connected by a slender neck. The bigger lobe is about 2.5 miles across, while the smaller one is about 1.5 miles wide. The jets seem to be coming from the neck region, which has been named Hapi, after the god in Egyptian mythology who makes the Nile River flood every year.

As the comet continues toward the Sun for its August closest approach, we expect many more spectacular jets to erupt on its surface. Stay tuned for wonderful images!

To see a first map of the regions on Comet 67P and what Egyptian gods the ESA scientists have named them after, see: http://sci.esa.int/rosetta/55297-comet-regional-maps/

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!]

Close-up View of a Comet

Today the Rosetta spacecraft closed in on Comet 67P (the P stands for periodic comet, meaning it comes around again and again every six and a half years. ) It's also known as Comet Churyumov–Gerasimenko (C-G). Look at the amazing image our cameras sent back, taken from a distance of only 177 miles.

The comet and the spacecraft are currently still about half way between the orbit of Jupiter and the orbit of Mars.  In this exciting rendezvous, Rosetta will match course with the icy comet and then stay with it as it gets closer and closer to the Sun and its ice begins to "sublimate" (turn from ice directly to a vapor in the vacuum of space.) 

We hope to stay with the comet for a year, as it goes inward and then swings back outward again, watching the Sun's light and heat playing with the comet all the while. In November, part of Rosetta will actually land on the icy surface of Comet 67P.

But for now, just enjoy the weird and wonderful image.   The comet's shape is definitely not symmetrical.  Is it two ice pieces that stuck together in an ancient collision?  Have past encounters with the Sun's heat resulted in this odd shape?

The comet is 2.5 miles wide, and you can see details as small as 17 feet (5.3 meters) across on our picture.   Can you see the individual "boulders" or "ice rocks" sitting on the comet's surface?

If you'll pardon the expression, what a cool picture!

By the way, click on the photo to see it bigger and with more detail.

A Wonderfully Scientific Science Fiction Film

Last night, thanks to the Wonderfest organization in San Francisco, I got a chance to see a science fiction film that was in theaters for so short a time that if you blinked, you probably missed it. It's called "Europa Report" and it is the story of a crewed expedition to Jupiter's intriguing moon Europa. This world, one of the four large moons of Jupiter discovered by Galileo, is an ice-covered ball that may well have a large liquid ocean under its surface.

You can see Europa's cracked surface on the picture I have posted above. (This is actually a montage of images from NASA's Galileo spacecraft, with additional image processing by Professor Ted Stryk to bring out more detail.) One possibility is that the dark cracks we see are places where material from deeper inside the Moon (perhaps even from the liquid ocean) is seeping up toward the surface.

In the movie (see the poster below), future astronauts (from a private space company) go to Europa to search for evidence of life. The complex story is told by interweaving the view from cameras in their suits and in their cabins, with footage they recorded for sending back to Earth and interviews with the mission controllers, who eventually lose contact with the ship. What the surviving astronauts eventually find is far more than the micro-organisms scientists currently hope might exist deep under the ice of Europa.

The film, by Ecuadorian director Sebastian Cordero, is now available on DVD and various internet film services. If you enjoy somewhat complicated but scientifically reasonable space stories, I commend it to your attention. If not, spend a little time Googling other images of Europa and check out one of the strangest worlds with which we have the pleasure of sharing the solar system.

Water Found on Largest Asteroid

Astronomers working with the Herschel space observatory have discovered water vapor coming from the largest asteroid in the asteroid belt, the one called Ceres (pronounced like "series"). By strict definition, Ceres is so big and round that it is no longer considered an asteroid, but is now designated dwarf planet number one (having been discovered on Jan. 1, 1801, long before Pluto).

Ceres is about 600 miles across and takes 4.6 years to orbit the Sun (Mars takes 1.9 years, while Jupiter takes 12 years.) The Hubble Space Telescope images of it (see one attached here) show lighter and darker areas. The water vapor is not evenly distributed around Ceres and there is more of it when Ceres is closer to the Sun, so there may be some ice that is sublimating (going from frozen form to vapor) in parts of Ceres.

At Ceres' distance from the Sun, ice on the surface would have all sublimated long ago, so this must be vapor coming from a deeper (frozen) layer, which was a surprise. Some astronomers think there may be enough water ice under the surface of Ceres to make an ocean. This is the first time water vapor has been detected in the asteroid belt, although we have seen it coming from a moon of Jupiter's and a moon of Saturn's. There may be plumes or "geysers" of water vapor coming from parts of Ceres, perhaps like the ones on Saturn's satellite Enceladus.

We will know a lot more about conditions on Ceres next March and April, when the Dawn spacecraft arrives for a rendezvous with Ceres and provides images with unprecedented detail of this intriguing member of our solar system. (Dawn gave us lots of great information about Vesta, the second largest asteroid, before it departed for Ceres in 2012.) Isn't it great how nature continues to surprise and delight us as we explore our cosmic neighborhood?

Billions of Earth-like Planets

This week, the University of California, Berkeley and NASA's Kepler Telescope project jointly announced that the ongoing discovery of planets around other stars had yielded some exciting statistics: It now appears that one out of five Sun-like stars has an Earth-like planet!

One out of five! This means there are likely to be BILLIONS of earth-sized planets orbiting at comfortable distances from BILLIONS of stars in our Milky Way Galaxy. All of us involved with SETI -- the Search for Extra-Terrestrial Intelligence -- are, of course, thrilled to hear this news. Our hope is that among all those planets, there are some where intelligent creatures with an interest in astronomy have developed and perhaps enjoy their own blogs with astronomy news like we do.

The latest stats about known planets around other stars are also record-breaking.  As of early November 2013, we have found 1039 planets around 787 stars beyond our solar system! (There are 173 stars so far where we have discovered more than one planet in the same system.)  In addition, the Kepler mission (which is searching for such planets from space) already has over 3000 candidate planets which are still being checked out!  And they still have a whole year's worth of data to go through.

I was interviewed on KQED, the San Francisco Bay Area public radio station, by Michael Krasny, the host of the Forum program, about all this -- and we were joined by the Berkeley graduate student who had done the basic work of making the estimates. If you want to hear the interview, it is available at:
http://www.kqed.org/a/forum/R201311060930 

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