28. October 2010 by RC Davison.

      For those of you that celebrate, appreciate, or just tolerate Halloween, I offer you a cosmic witch to look out for!

      Catching some rays from Orion’s blue supergiant - Rigel, the witch is actually a reflection nebula (hence the bluish color) that is over 50 light-years long.   The Witch Head Nebula (IC 2118) is about 1000 light-years distant, so we have nothing to fear from this witch on Halloween!

Click the link for more information about, and a larger image of the Witch Head Nebula.

Till next time,

RC Davison

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27. October 2010 by RC Davison.

          When I look at a globular cluster like Omega Centauri I always imagined that the 10 million stars in the cluster rotated majestically about a central mass in an orderly fashion.         

Thanks to some new work by two astronomers from the Space Telescope Science Institute in Baltimore, Md, my peaceful, orderly vision of a globular cluster has been trashed!  

            Jay Anderson and Roeland van der Marel, using data from the Hubble Space Telescope, have measured the velocities of some of the stars at the heart of the cluster and their motion is far from peaceful!

             In the close-up image below, we see the brilliant blue and red stars that reside in the center of this ancient globular cluster.  The area in the rectangle is magnified and displayed below showing the relative velocities of the stars contained within.

Source: Hubblesite.org

        This motion was gleaned from images Hubble took in 2002 and 2006.  Its precise optics allowed the astronomers the ability to measure the relative motion of these stars over such a short period of time. 

         In the Hubble clip below, you will zoom into the heart of Omega Centauri and ultimately see the predicted motions for these stars over the next 10,000 years.  It is interesting to note that this random motion gives astronomers clues that may dispel the theory of a massive black hole at the center of globular clusters.  There may be a black hole present, but it would not be equivalent to the massive black holes found in the center of galaxies, like the one at the center of the Milky Way, which is about 4 million times the mass of our Sun.

Till next time,

RC Davison

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25. October 2010 by RC Davison.

“Inside The Milky Way” is a new production by the National Geographic Channel that aired Sunday night and will be broadcast again on Thursday, October 28th at 9 pm.  I saw most of the program and highly recommend it.

Stunning visuals, animations, and the latest hot topics in astronomy are intelligently discussed in this 2-hour program.  Black holes, dark matter, galactic superclusters, and the Andromeda/Milky Way collision (In about 2 billion years - don’t sweat it!) are some of the topics covered.  (Just ignore the sound effects for the supernova!)

Check out the web site for some videos and photos.  Enjoy!

Till next time,

RC Davison

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16. October 2010 by RC Davison.

     My post on August 21, 2010, “Do They Know We’re Here?” contains a bit of misinformation, which I hadn’t thought of until reading the latest Planetary Report from the Planetary Society.

While we’ve been experimenting and transmitting radio signal for over a 100 years, those early transmissions were low frequency, typically 1 MHz or less.  The ionized layer of our atmosphere - the ionosphere, reflects those signals back down to the surface, so they won’t escape the planet.

If any of you have listened to AM radio (Remember that?) at night, you find that you can pick up stations from 100s to 1000s of miles away, whereas you can’t hear them during the day.  This is because at night, the sunlight is no longer showering the atmosphere with UV radiation, which knocks electrons off the oxygen and nitrogen atoms charging them - ionizing them.  The lower layer of the ionosphere rapidly dissipates when the Sun sets, leaving the higher layers to reflect the AM transmissions, allowing them to reach much further.

We don’t see this with our FM radios,  because they operate at much higher frequencies (in the 10-100 MHz range) and don’t rely on the ionosphere to  reflect them to your radio.  For your radio to receive your favorite FM station, you have to be able to receive the signal directly from the transmitting antenna, this is why they are called “line-of-sight” transmissions.  These higher frequencies were used commercially for FM radio and early television in the early 1930s, and they blasted right through the ionosphere and out into space.

So, a long winded explanation to say that we’ve really been broadcasting to the cosmos for about 75 years, as opposed to the 100 years mentioned in the earlier post.

Comments always welcome!

Till next time,

RC Davison

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9. October 2010 by RC Davison.

     Initially, I was just going to put up a link to the European Southern Observatory’s list of top 100 images, which has enough pictures to keep any fan of the cosmos happy.  But, I made the mistake of checking out NASA’s Hubble site, which has a huge collection of images, and I compounded that mistake by looking at the European Space Agency’s (ESA) site for Hubble.  Wow!  I think I’ve overloaded my neural-net!

There is just way too much to look at on these sites!  As a tantalizing tidbit, take a look at this beautiful Hubble image of the spiral galaxy NGC 5866 seen edge on.

Click on the link above for larger images (down-loadable) where you can enjoy the exquisite detail Hubble captured of this galaxy.

One last thing.  ESO is running a contest - ESO’s Hidden Treasures for anyone that has an interest in creating a new image from their data archives.  They provide instructions on what you have to do to create the image, but hurry, the contest ends on November 30, 2010.

Till next time,

RC Davison

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8. September 2010 by RC Davison.

    My fascination with the cosmos is due in part to a wonderful series that ran on PBS in the 1980’s called Cosmos. I will forever be indebted to Carl Sagan for escorting me, and millions of others on a journey of the imagination to explore the Universe we live in.  I’ve never met Dr. Sagan, but for some strange reason I find myself missing him.  Maybe it is because he spoke to a future that included us exploring this amazing cosmos in which we live, and that our challenges came not from each other, but from trying to understand the Universe.

There is a web site called the Symphony of Science, which has a collection of songs and videos that feature Carl Sagan and other prominent scientists in a rather interesting mash-up of scientific dialog, acoustic and electronic music and effects.  The first to be produced is called “A Glorious Dawn” and you may already be aware of it.  I found it a very moving and uplifting song/video, and I’m not one for “auto-tuning”.  I’d strongly suggest you check them out if you have a chance, as they are pleasing on many levels, from the background musical, the visuals and especially the lyrics.

Lastly, I’d like to leave you with an image of a binary star system (LL Pegasi - also known as AFGL 3068) that the Hubble Space Telescope has taken, which I feel is the embodiment of the Cosmos Carl Sagan talks about.  It is visually beautiful, and as you understand how the structure was formed, it is even more fascinating.  I won’t go into details about it, you can check out the Space Telescope site, and Phil Plate’s Bad Astronomy Blog (which is really good!) for more details and discussions on how it formed.

Thank you, Carl…

Till next time.

RC Davison

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2. September 2010 by RC Davison.

It is way too easy to dismiss the Universe as a static entity that doesn’t change as we go about our daily activities.  We catch a glimpse of the night sky from time to time, but never stop and watch it night after night as our ancestors did.  Thanks to modern technology we can compress years into seconds, and see amazing things unfold that we would have missed otherwise.

A good example of this is the supernova 1987A (which occurred in 1987) in the Large Magellanic Cloud.  In this video you can see how the shock wave has propagated through space from 1994 to 2006. This image from Hubble (below) shows in even better detail the shock wave as it heats the gas and dust that were ejected from the star thousands of years before it went nova.
Source: Hubblesite.org

Another video that always amazes me is one from the European Southern Observatory (ESO) that shows the stars at the center of the Milky Way orbiting around a dark common point over a period of16 years.  This common point is undoubtedly a massive black hole.  It can not be seen in the images, but by the motion of the stars, the mass of the object has been calculated to be about 4 million times the mass of our Sun.  You can read more about this in an article I did: “Stellar Motion: Do Stars Really Move?”

Our Universe is constantly changing.  We just have to slow down enough to see it.

Till next time,

RC Davison

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24. July 2010 by RC Davison.

NASA’s Kepler mission was launched in March of 2009 with the purpose of simultaneously studying about a 100,000 stars located within a 10 degree field in the direction of the constellation Cygnus.  Kepler is looking for the dimming of the light from these stars to indicate a planet passing, or transiting in front of the star. To label a detection a possible planet, Kepler needs to see the transit at least 4 times.

Within a little over a year’s worth of operation, Kepler has found over 700 possible planets!  Since we’ve been turning telescopes to the sky we’ve only managed to find about 400 exoplanets, and these discoveries have only come in the last 5 -10 years!  But, just think about this for a moment.  Kepler only sees planets that pass between the stars and Earth (in our line of sight), and only those that have passed in front of the stars at least 4 times since it has been watching.  What about those planets that are orbiting perpendicular to our field of view, and what about those planets that have orbital periods of 3, 5, 10, or 20 years or more?

There are a lot more planets out there than we are seeing and I think a lot more that we may have ever imagined!  The more planets, the greater the chances of extraterrestrial life.  What wonders await us in the cosmos?!

(Check out Kepler’s web site for much more great info about this mission.)

Till next time

RC Davison

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