Tuesday, August 28, 2012

Star Corpses Help Us Prove Einstein Right



One of the most intriguing predictions of Einstein's theory of relativity is that, just like there are light waves and sound waves, there should also be GRAVITY WAVES. When the arrangements of massive objects in the universe changes (like two stars orbiting each other), Einstein's theory predicts that waves of gravity energy should be be given off.

But gravity waves are very, very weak and hard to detect. We have gravity wave telescopes operating, but so far they have not succeeded in catching some big gravity change that would give off enough waves to be measurable. So astronomers are turning the idea around. If we could find two massive stars in the universe that are in orbit, they should be giving off these subtle gravity waves and should be losing energy. That means the two stars will -- as their motion energy is lost -- spiral inward toward each other, something they would not normally do. The more compressed the star, the bigger the effect. Dead stars, that have fallen inward -- gotten "squozen" in death (as I like to say) are excellent subjects for testing this prediction.

Two astronomers in the mid-1970's, including one of my undergraduate advisors, Dr. Joseph Taylor, discovered two star corpses (collapsed stars) that showed exactly this kind of behavior. There were the two dead stars, called neutron stars, minding their own business in space, lost in each other's gravity embrace. Yet, they were very slowly approaching each other in orbit. And the energy they lost was exactly what Einstein predicted. Taylor and Russell Hulse won the 1993 Nobel Prize in physics for their painstaking observations of this pair. But their measurements were done with radio waves, since that was the only way to see these particular star corpses.  

(For those of you who know a little astronomy, the precise story is that most neutron stars are only observable as "pulsars" -- objects that give off regularly pulsing radio waves.  As the two pulsars orbit, they lose energy and their pulses change as they get closer to each other.)

Now, a larger team of astronomers has just announced finding a different pair of dead stars (called white dwarfs) that show the same spiraling behavior, but shining in visible light. The nameless pair of star corpses is about 3,000 lightyears away. As they orbit close around each other (taking only 13 minutes for an orbit!), we see one eclipse the other. Between April 2011 and today, the eclipses have come 6 seconds earlier, as the two dead stars lose energy and approach. This is, again, exactly what we would expect if Einstein is right, and the pair is losing energy via gravity waves.

(Just as a lightbulb loses energy as it shines away light, and you have to pay the electric company to replace it, so it seems orbiting stars slowly lose energy as gravity waves. The difference is that there is no source of new energy, and so the stars simply fall slowly toward each other.)

How nice that Einstein's ideas, now almost 100 years old, are being confirmed in some of the strangest astronomical environments we can find. He'd be proud.






Wednesday, August 22, 2012

"Doomsday 2012" and Cosmophobia


Photo: "Doomsday 2012" and Our Schools

As students return to school this fall, the media and web hype about Doomsday 2012 (the end of the world because a planet will hit us, something will align in the sky, the Earth's rotation or axis will change, or just because the ancient Maya said so) promises to reach a final, fevered pitch.  Those of us in science and science education are preparing to respond to concerns from people (especially young people) who are genuinely worried or confused. 

Two new resources are now available for educators, parents, 
youth group leaders, to address fears that world-wide disaster is coming on Dec. 21, 2012.  Perhaps you can let your favorite teacher, school counselor, scout leader and other adult working with kids know about these. 

I have put together (with lots of help) a guide to accessible written and audio-visual materials on this topic (most of them freely available on the Web).  You can find it in the on-line publication "Astronomy Education Review" at:
http://dx.doi.org/10.3847/AER2012021 
(click on the "Download PDF" link under the author's name for
the easiest way to see the entire article).

And a video recording of a panel I had the privilege of leading on "Doomsday 2012 and Cosmophobia" at this summer's meeting of the Astronomical Society of the Pacific has now been posted by NASA's Lunar Science Institute at:
http://lunarscience.nasa.gov/articles/cosmophobia/

"Cosmophobia" is NASA astronomer David Morrison's name for the  unnecessary fear of celestial events and phenomena. When David and I were young, new discoveries in the sky were a source of awe and fascination.  Now, we are observing more and more people asking, as new things are discovered, "Should I be afraid?"  It's kind of sad, given that we live mostly in splendid cosmic isolation, and most things in the universe are really much too far away to hurt us.  

Please help spread the word that students will still have to take exams and we all still have to pay taxes in 2013.

As students return to school this fall, the media and web hype about Doomsday 2012 (the end of the world because a planet will hit us, something will align in the sky, the Earth's rotation or axis will change, or just because the ancient Maya said so) promises to reach a final, fevered pitch. Those of us in science and science education are preparing to respond to concerns from people (especially young people) who are genuinely worried or confused.

Two new resources are now available for educators, parents, youth group leaders, to address fears that world-wide disaster is coming on Dec. 21, 2012. Perhaps you can let your favorite teacher, school counselor, scout leader and other adult working with kids know about these.

I have put together (with lots of help) a guide to accessible written and audio-visual materials on this topic (most of them freely available on the Web). You can find it in the on-line publication "Astronomy Education Review" at:
http://dx.doi.org/10.3847/AER2012021
(click on the "Download PDF" link under the author's name for the easiest way to see the entire article).

And a video recording of a panel I had the privilege of leading on "Doomsday 2012 and Cosmophobia" at this summer's meeting of the Astronomical Society of the Pacific has now been posted by NASA's Lunar Science Institute at:
http://lunarscience.nasa.gov/articles/cosmophobia/

"Cosmophobia" is NASA astronomer David Morrison's name for the unnecessary fear of celestial events and phenomena. When David and I were young, new discoveries in the sky were a source of awe and fascination. Now, we are observing more and more people asking, as new things are discovered, "Should I be afraid?" It's kind of sad, given that we live mostly in splendid cosmic isolation, and most things in the universe are really much too far away to hurt us.

Please help spread the word that students will still have to take exams and we all still have to pay taxes in 2013. ·  · 

Sunday, August 19, 2012

Mars Update



In this beautiful picture, you can see what the NASA publicity team is calling the "Promised Land" on Mars. The slope of Mount Sharp beckons in the distance in this color image taken by the Curiosity Rover's mast camera. The Mars light, by the way, has been adjusted on this image to show you what the scene would look like in Earth sunlight.   You can see that they have added a white bar on the mountain which is 2 km, or about 1.2 miles, wide.

The highest point on Mt. Sharp rises about 3 miles above its base. Note that in the picture, the lower parts of the mountain are darker than the rest. It is this dark region that we believe was covered with water long ago and is expected to show us the chemical and mineral traces of having been long submerged.

Also check out the image below for a bird's eye view (or more precisely, a spacecraft's eye view) of where Curiosity is now (green dot), where it is going first (Glenelg blue dot), and where it will approach Mt. Sharp (the blue dot in the center). Note that the elevation rises as you move toward the bottom right in this picture. 










Today, Curiosity fired its laser beam for the first time at a rock on Mars, with 30 pulses over 10 seconds. This vaporizes the rock, so that Curiosity can measure very precisely what it is made of. Scientists using the ChemCam instrument were delighted with the information coming into their little "mini-telescope" from the flash of the vaporized rock.  For more information, see: 

Wednesday, August 15, 2012

A Huge and Distant Cluster of Galaxies (and a Movie)



I want to introduce you to a short, but truly mind-boggling movie and then share a piece of news with you. 

All stars are organized into giant islands called galaxies. We live in one 
such island, called the Milky Way Galaxy, and our telescopes show many billions of other galaxies all around the sky. Like explorers on an unknown continent, we have recently been trying to map the way all these galaxies are distributed through space. Perhaps the most impressive such mapping project is called the Sloan Digital Sky Survey, and they just released a short film allowing you to fly through 400,000 galaxies whose positions in three-dimensional space have now been measured. Here is the movie: 
http://www.youtube.com/watch?v=08LBltePDZw 

Note that each little object on your screen is a galaxy of billions of stars (stars like the Sun)! Also note that the galaxies are not evenly distributed. Just like stars, they tend to be "social" -- they collect into groups (or galaxy clusters). 

Just today, astronomers announced the discovery of one of the largest galaxy clusters ever seen, nicknamed the Phoenix Cluster. It contains enough material (in many many galaxies) to make more than 2 million billion Suns. And it is almost 6 billion light years away, which means the light we see tonight from this huge grouping of galaxies left on its way to us before the Sun and the Earth ever existed. Wow. 


What makes the Phoenix cluster of special interest to astronomers is that, at its center, the gas falling in from all over the cluster is leading to a huge rash of newly forming stars. 740 new stars form in the middle galaxy of the cluster EVERY SINGLE YEAR. Many such galaxy cluster have a core that is "red and dead" -- with little star formation going on in the central galaxy. But this cluster has a center that's "blue and new" -- with lots of new stars being born. 

You can just stop there if (like many people) your head now hurts from the movie and the huge numbers I am throwing around. Just let the feeling of the immensity of the cosmos overtake you. (It helps a lot when you can't stand the pettiness of presidential politics these days.) Or, for more on the Phoenix Cluster see:

http://chandra.harvard.edu/press/12_releases/press_081512.html
or
http://www.skyandtelescope.com/news/Heavyweight-Cluster-166282866.html

Thursday, August 9, 2012

Color Mars Panorama and Meteor Shower Saturday Night


The first color panorama looking around the landing site has been taken by the cameras on the mast of the Curiosity rover.  In the picture, we are seeing a late afternoon scene, with the dramatic shadow of the rover, the reddish martian sand, and the grey splotches made where the rocket exhaust disturbed the ground.  The set of stitched-together images shows the scene 360 degrees around the rover; as if we were right there with Curiosity. I love it.  Even better images are going to be taken, but this first look around is what the scientists have been waiting for to get their bearings.
See: http://www.nasa.gov/mission_pages/msl/multimedia/pia16029.html
for the version with NASA's caption.

Coming back down to Earth, this Saturday night and Sunday morning are the peak of the Perseid (pronounced Purr--see--ud) meteor shower for 2012.  What that means in English is that, if you go outside and away from city lights after about 11 pm Saturday evening or early Sunday morning, you will see more shooting stars than usual.  If you are patient, allow your eyes to get adapted to the dark, and find a spot where you have a good view of the whole sky, you should be rewarded -- over time -- with a good number of chunks of cosmic material burning up in our planet's atmosphere.

The chunks in this "shooting star" shower are left over from an old comet called Swift-Tuttle, which has passed our way many times over the eons, and left a lot of dust in its wake.  When the Earth intersects that stream of dust and dirt, we get a shooting star each time a piece burns up by air friction.

I recommend viewing the shower with someone with who you enjoy spending time in the dark.

For more, see the nice article from Sky & Telescope magazine at: http://www.skyandtelescope.com/about/pressreleases/Perseid-Meteors-in-Their-Prime-165482256.html

Thursday, August 2, 2012

Seven Minutes of Terror: Curiosity Rover to Land on Mars


If all goes well, and keep all your fingers crossed that it does, the most complex laboratory ever sent to another world will land on Mars next Sunday night. The Curiosity Mars Rover is slated for Ma
rs touchdown Sunday, August 5, at 10:31 PM Pacific time, in a never-before-tried rocket-powered sky-crane landing. To see, what's involved and why NASA's Mars scientists all have their nails bitten down to the fingertips, check out the video about the "Seven Minutes of Terror" after the craft reaches the top of Mars; thin atmosphere:

http://www.youtube.com/watch?v=Ki_Af_o9Q9s

 

 

 

Here is a great image from the Jet Propulsion Laboratory, which builds and manages so many of our robot probes to the planets. This show the three generations of Mars rovers, the little Sojourner at the front left, S
pirit/Opportunity to the left of the two technicians, and then big Curiosity (the one that we hope to land on Sunday) on the right. NASA says if Spirit and Opportunity were golf carts, then Curiosity is a car. It has 10 science instruments, weighs almost one ton, and requires too much power to use solar cells (as the previous generations of rovers did). It has a generator powered by radioactive plutonium dioxide on board. 

Among its tools is a microscope that can see things as small as the width of a human hair! And the microscope tool carries a small light so it can do night work. Its laser can vaporize rocks up to 23 feet away, and "smell" what they are made of from the vapor. Since (at the time of the landing) messages from Earth will take 14 minutes to get to Mars, the rover has artificial intelligence software for making any immediate decisions that are required. The question is, is Curiosity smarter than your little brother?