Black Hole at Center of the Milky Way is Found to be Cooking its Dinner

Astronomers working with the European Herschel Space Observatory have discovered really hot gas in the vicinity of the monster black hole at the center of our Galaxy. Over the years, many lines of evidence have shown us that there is a black hole with enough material to make 4 million Suns at the heart of the Milky Way. The new observations, made using infrared (or heat) rays, show that gases such as water vapor and carbon monoxide have been heated to about 1000 degrees Centigrade within a lightyear of the black hole.

While energy from nearby stars may also be heating this inner gas, the astronomers can't account for so much heat from stars alone. They think that great streamers of gas heading toward the black hole may be colliding and the shock waves from the collisions may be significant contributors to the heating. Some of the streamers of gas will someday be "eaten" by the black hole. In other words, like many a hungry diner, the black hole appears to be "cooking" its dinner in anticipation of eating it.

In fact, other observations have recently shown a cloud of gas weighing as much as several Earths, falling to its doom much closer to the black hole. This cloud may be consumed by the black hole as soon as the end of 2013. When such clouds actually spiral inward to their doom, they heat up a lot at the end. The last thing we observe from them before they fall into the black hole (and are no longer visible) is a "burp" of x-rays. Several x-ray telescopes in space are prepared to record such burps when they happen.

If you are cooking a barbecue this Memorial Day Weekend (a holiday in the U.S.), you can enjoy the idea that some serious cooking may also be going on at the center of our Galaxy. The center region is 26,000 lightyears away from us, so none of this poses the least danger to planet Earth and its cooks.

(By the way, to see one of the lines of evidence for the existence of the monster black hole, we recommend a great new movie made from observations by astronomer Andrea Ghez' group at UCLA. The movie shows the whirling orbits of stars very close to the black hole, being pulled around by the enormous gravity of the black hole. Check it out at:

http://www.astro.ucla.edu/~ghezgroup/gc/images/media/ghezGC_comp3-18_H264_864.mov

Note that each second of the movie shows two years of star motion. It's enough to make you dizzy.)

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

Third Closest Star to the Sun is Not A Star At All

The third closest star system has recently been found and it turns out to be a pair of faint "brown dwarfs" -- failed stars that just don't have what it takes to be a full-fledged sun. The new system -- known as Luhman 16, after its discoverer -- is 6.6 light years away. This means that light traveling from there to us would take a bit more than six and a half years to cross the distance between us. (The nearest star system is about 4.4 light years away, and the second nearest is 6 light years from us.)

I heard about this system from Dr. Gibor Basri, one of the discoverers of brown dwarfs, who gave a talk in the Silicon Valley Astronomy Lecture Series, which I have the privilege of organizing and moderating. Brown dwarfs were first named as part of her thesis by Jill Tarter, now the leading scientist searching for signs of extra-terrestrial intelligence, but then a graduate student getting her PhD at Berkeley. They are globes of hot gas that just don't have enough material to sustain the vast release of nuclear energy which powers ordinary stars.

It's the same in space as in Hollywood -- not everyone has what it takes to be a star. Just as many actors with ambitions to be in the movies wind up waiting on tables in Los Angeles, not every ball of hot material in space gets to be an on-going star. Some just glow briefly, especially with heat-rays (infra-red), but then slowly fade away. In fact, it was with the WISE infra-red telescope that astronomer Kevin Luhman discovered the brown dwarf system which now joins our list of intimate neighbors in space. (Its other name is WISE 1049-5319, which is a code that tells astronomers its location in the sky.)

In the picture with this article, you can see a later image of the system, taken with the giant Gemini telescope in Chile, that allowed astronomers to see that there were actually TWO brown dwarfs in the same star system, orbiting each other. We estimate they take about 25 years to go around. Interestingly, the Luhman 16 system is not only our third closest neighbor, but now appears to be the closest neighbor of our closest neighbor, the Alpha Centauri system. In other words, if you lived in the triple star system we call Alpha Centauri, and someone asked you, what's your closest neighbor in space, you would say Luhman 16. (Until recently, we thought WE were their closest neighbor, just like they were ours. But the brown dwarfs, which lie in the same rough direction as Alpha Centauri, but beyond them, now take our place as their closest neighbor.)

It's remarkable that something this close was just discovered. But that is a testament to how faint these failed stars really are. We are therefore able to find only the closer ones and many others that are further away remain undiscovered. The first brown dwarf was only found in 1995; today hundreds are known (thanks mostly to the WISE telescope.)

Dr. Basri's talk was videotaped and will eventually be up on our new YouTube Channel for the Silicon Valley Astronomy Lectures. You can go there now and see many other talks by noted astronomers: http://www.youtube.com/SVAstronomyLectures/

A Gorgeous New Hubble Image and News from Kepler

Scientists working with the Hubble Space Telescope have just released a magnificent new image of one my favorite astronomical objects -- the Horsehead Nebula, a great cloud of "cosmic dirt" in the constellation of Orion. What makes this image a little different from usual is that we are not seeing the tower of dust with visible light, but with heat-rays (what scientists call the "infra-red.") 

It is in such clouds of dust and gas that new stars and planets are being regularly born. Because dust can block regular light, infrared images like this allow us to peer deeper into these regions of star birth. This particular image is about 2.5 light years across (where each light year is about 6 thousand billion miles) -- so we are seeing a good-sized pillar of cosmic "raw material" here. (Yet the Horsehead is just a part of a much larger complex of gas and dust called the Orion Molecular Cloud, which is roughly 1500 light years away from us.)

You can see two recently born stars at the top ridge of dust in the Horsehead in this image, confirming that star birth is happening in this dusty clump. Note that the colors we see on this picture are not real (since these are rays our eyes are not sensitive to.) The colors were picked by Hubble scientists to give a sense of the dustiness of the Horsehead.

You can contrast this infrared picture with a visible-light Hubble image taken with the Hubble in 2000-2001:
http://hubblesite.org/newscenter/archive/releases/2001/12/image/a/

and with an image of a larger region around it taken with the Canada-France-Hawaii Telescope on the ground at:http://www.nasa.gov/multimedia/imagegallery/image_feature_89.html

Aren't they gorgeous images?

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In other news you may have read that the Kepler mission, photographing 150,000 stars regularly in its search for planets orbiting other stars, has found three more planets that are just a little larger than Earth and orbiting in the "habitable zone" of their stars -- where water could be warm enough to be liquid. 

For the full story, see: http://www.kepler.nasa.gov/news/index.cfm?FuseAction=ShowNews&NewsID=243

That page gives you access to the quick info, the paintings of what the planets might like, animation, etc. To get the story in a more organized way, scroll down toward the bottom and click on the link to the full NASA news release.

The gist of the discovery is that we are finding more and more planets that are roughly earth-like -- perhaps a bit bigger, not always around the same kind of star as our Sun -- but Earth-like in their temperatures and other conditions. The Kepler team said that the current discovery is just an appetizer. Many more such planets may be among the 2740 candidate planets Kepler found that they are still examining and not yet ready to confirm.

The Old Blogger Gets an Award

I'm humbled to tell you that the nation's science teachers have given me an award -- the 2013 Faraday Award for Science Communication. Given each year by the National Science Teachers' Association, this award recognizes "an individual who has inspired and elevated the public’s interest in science."

Among previous winners are Ira Flatow, the host of NPR's Science Friday show, and astronomy educator Dennis Schatz, my good friend and the Vice President of the Pacific Science Center in Seattle.

What's especially wonderful is that the award is named for Michael Faraday, the 19th-century British physicist who discovered the relationship between electricity and magnetism, and was one of the greatest communicators of science in history. That's his picture on a British bank-note. Faraday is someone I have admired for a long time (and I am not alone -- Einstein had a picture of him on the wall of his study!) Among other things, Faraday spoke out forcefully for the importance of science education in our lives and for skeptical thinking about paranormal and psychic claims. What an honor to be associated with his name.

I'm accepting the award Friday night at the annual conference of the National Science Teachers Association in Texas.

You can read the full story of the award here:http://www.foothill.edu/news/newsfmt.php?sr=2&rec_id=2999

Here is a favorite quote from Faraday: “[A] lecturer should give the audience full reason to believe that all his powers have been exerted for their pleasure and instruction.”

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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.