Follow this link to connect to the new blog.

See you there,

RC Davison

    Planetary nebula are the remains of a star like our Sun as it goes through the final stages of its life expanding and blowing off its outer layers.  The bright blobs embedded in the nebula are areas of gas that are energized by ultraviolet light from the star at the center.  The blue-green color of the nebula reflects the hydrogen and oxygen present, with red indicating nitrogen.  The Necklace Nebula lies about 15,000 light years from us and is located in the constellation Sagitta.

It’s interesting to compare this planetary nebula with the remains of the supernova 1987a:

     Another piece of cosmic jewelry, but one made from a very different process and from a star that was much larger than our Sun. The supernova is the foundry that produces all the heavy metals we have today, from the iron in the hemoglobin of your red blood cells to the gold and silver in the jewelry you may be wearing right now.

     Both of these nebulae are still evolving, and as time passes they will continue to evolve into new shapes, and eventually (10s to 100s of thousands of years) they will fade from view.  But, their remains will fuel the next generation of stars and planets in the cosmos.

Till next time,

RC Davison

     The end of the shuttle era came on Thursday, July 21 at 5:57:54 a.m. when Atlantis came to a full stop on the runway at the Kennedy Space Center.  The amazing image below is a fitting finish to an amazing program, regardless of any arguments about traveling to low Earth orbit versus going to the Moon or Mars.

Here’s a link to a larger image.

     Some statistics for Atlantis:  It has traveled 125,935,769 miles while it orbited the Earth 4848 times and spent a total of 307 days in space.  It’s good to have all the shuttles back safely on the ground.

On a Orbital Maneuvers related note: I’ve put up a video promo for the book on YouTube.

Till next time,

RC Davison

Also, the Kindle version is now $4.75 and for other digital formats, which you can find at Smashwords, it’s $4.99.

Till next time,

RC Davison

     I was initially going to talk about some fascinating images of sunspots showing their structure in a way never seen before, but the Sun made an announcement on Tuesday that took solar astronomers by surprise and has moved to the top of the list.

      On June 7^th there was a huge eruption on the surface of the Sun, very different from anything observed before.

      The above image shows this huge prominence. This gives you an idea of its size and how much of the Sun it covered, but check out the video below to see how dynamic this event was.

      The video shows the eruption as seen by the Solar Dynamics Observatory at two different energies. The second, or greenish-blue image is looking at shorter wavelengths, or higher energy emissions. The other images with the disk in the center (an instrument called a coronagraph) are from the Solar and Heliospheric Observatory’s (SOHO) LASCO coronagraph and STEREO’s (Solar Terrestrial Relations Observatory). If you watch the video closely you will see material falling back to the surface of the Sun creating ejecta as they land.  For more information and more complete videos with descriptions go to The Sun Today.

Now on to something more sedate – sunspots.

      The Sun is a very dynamic object, as evidenced by the images above, but from our place in the Solar System it seems pretty quiet and stable. The surface of the Sun is a frenzy of activity and this is no different when you approach the cooler sunspots that dot its surface.

     Work done by Göran B. Scharmer, Vasco M.J. Henriques, Dan Kiselman, (all from the Institute for Solar Physics of the Royal Swedish Academy of Sciences and the Department of Astronomy at Stockholm University), and Jaime de la Cruz Rodríguez (University of Oslo) has shown that the structure of the sunspot is a heaving mass of cells or filaments almost 1200 miles or about 2000 km long and about 90 miles (150 km) wide, which can be seen in the above image. The brighter, hotter filaments are areas of hot matter that is upwelling at speeds of 6,600 mph (10,800 kph), while the darker filaments are sinking at speeds of about 2,200 mph (3,600 kph).

      The image below shows the speed of the sunspot’s filaments as measured by Doppler shift. The red filaments are moving away, or sinking while the blue ones are rising and moving toward the surface.

For more information and images visit the Institute for Solar Physics

      These images should humble us, as they are indicative of how much we don’t know about the cosmos, let alone our nearest star.  There is so much to learn…

Till next time,

RC Davison

This discovery was made by using a technique called gravitational lensing or microlensing in this particular case.  According to Einstein’s General Theory of Relativity, the gravitational field of a massive object will bend light that passes through it.  This technique has been used to view distant galaxies that are behind an intervening large cluster of galaxies, which magnify and distort the image of the more distant objects.

In the case of gravitational microlensing, the intervening objects are these rogue planets and the distant objects are stars.  The alignment of the star, planet and Earth is almost perfect, such that when the planet passes in front of the star its gravitational field causes the star to brighten and dim in a predictable fashion.  This is a brief event and will not repeat itself.

These objects are similar in mass to Jupiter.  And, if they are truly planets or possibly brown dwarf stars (small stars that generate heat but are too small to trigger the fusion process to burn brightly), they may have been ejected from their solar system of birth through the normal dynamics that force a solar system into a stable state.  Interestingly, this challenges the definition of planet, which was decided upon by the International Astronomical Union (IAU) and led to Pluto’s demotion to dwarf planet, but that is a a discussion for another blog.

The objects detected are fairly massive, which begs the question: What about smaller Earth-like planets?  Can we see them and how many of them are there out there?  As usually happens in the world of astronomy, discoveries bring more questions than they answer.

The discovery of these objects challenges the current theories of planetary evolution and possibilities for life in the Universe.  More research in this area will be conducted when NASA’s Wide-Field Infrared Survey Telescope (WFIRST) is launched, allowing for the faster blips of light to be detected, indicative of Earth-mass type objects.

Till next time,

RC Davison

First:  The European Space Agency posted a very nice video showing the Andromeda Galaxy in light from X-rays to gamma rays.  About a third of the way into the video, one can see variable stars pulsing and other stars flashing as they go nova, thanks to the view from the XMM-Newton X-ray telescope. Check out “Andromeda’s coat of many colours“.  (Check out the post on 6, January 2011 under the galaxy category for more information about Andromeda.)

Second:  An image posted on the Astronomy Picture of the Day site by Juergen Michelberger shows in very unique detail how stars and planets are affected by Earth’s atmosphere.  Or, more appropriately, why stars twinkle and planets don’t.

     The star, being much further away from Earth than the planet Mars, presents an image that is much smaller in diameter than Mars.  This smaller point of light is affected by the variations of the Earth’s atmosphere due to temperature and moisture much more so than the larger source of light from the planet.  Consequently, the star’s image is randomly refracted, causing it to vary in color and brightness, while Mars shines on steadily over the ten second exposure.  The intricate image is due the camera being swung about.  Check out the link to APOD above for more information about this unique image.

Till next time,

RC Davison

 (Link to larger images)

     The blue “icing”at the top of the image are hot blue stars that have formed in the wake of the collision.  You can also see a region of new star formation in the center of the smaller galaxy, also most likely due to the collision.

     But, there are jewels strewn all about in this image: A small blue galaxy to the left of the larger UGC-1810 and a red spiral galaxy visible between its arms to the lower right.

   This clip will show you where the galaxies are and zoom in to them.  But, if you can, download the largest image possible, zoom in and explore this beautiful image.

    It is also noteworthy that this image commemorates Hubble’s 21st anniversary of operation in space.  It’s hard to imagine that is has been that long!

     A note about housekeeping on the site.  I’ve categorized the blog posts so it will be easier if you are looking for a particular post to search by category.  The categories used are listed at the bottom of the post and you can click on them to sort the blog.  They are also listed on the right side of the web page.

• Astronomy
• Cosmology
• Galaxy
• Humans in Space
• Orbital Maneuvers
• Solar System

Hopefully this will be of use to you in the future.

Till next time,

RC Davison

     The science of astronomy is fascinating in that it involves some of the most bizarre concepts in nature.   But, it can be one of the most frustrating fields of study because we must do everything at a distance.  We can’t touch a star.  We can’t see the evolution of most events in the cosmos because the time they take far exceeds our meager lifetimes. (That is, short of an event like a supernova.) Everything we know about the cosmos has been learned by observation via the electromagnetic spectrum, historically in the visible wavelengths and today we cover the entire electromagnetic spectrum.   It is with these observations, coupled with a basic understanding of physics and chemistry learned on Earth, along with theories developed by some very intelligent people that have led to new discoveries in the cosmos.

      It has been theorized that stars that orbit a black hole, (like the ones that move around the black hole at the center of our galaxy) may eventually be pulled into the black hole.   This unfortunate star would be ripped apart by the tidal forces exerted on it from the black hole, and its remains would be pulled past the event horizon into the waiting singularity.  This star stuff would release tremendous amounts of energy as it spiraled down into the black hole, moving faster and faster and approaching relativistic speeds.  This energy would be radiated away from the black hole in high energy jets that are perpendicular to the disk of debris falling into the black hole.   This is theory.  We haven’t actually seen this happen – yet.

      An event that was documented on March 28, 2011 by the Swift gamma-ray telescope (gamma-ray burst (GRB) 110328A), followed up in the visual part of the spectrum by the Hubble telescope and finally confirmed by the Chandra X-ray telescope may have identified such an event.   The object located in a galaxy 3.8 billion lightyears (ly) from us in the constellation of Draco, visible from the northern hemisphere.   This is what Swift, Hubble and finally Chandra saw as they hunted down the source of the gamma rays:

(HubbleSite.org)

       The Swift telescope picked up on a gamma-ray flash and documented a series of flashes, which instead of getting dimmer actually got more intense.   This is not typically seen. When a star goes supernova it emits an enormous burst of energy that fades over the a period of 3-4 weeks or more as indicated in the graph below.

      What Swift saw was this:

(HubbleSite.org)

      Distinctly different.   If the theory is correct then we are seeing these bursts of energy because the orientation of the black hole relative to Earth is such that these jets point our way.

      The proposed scenario that matches up with the observation is depicted in the image below:

(HubbleSite.org )

      Frustratingly, we can’t see this!  We can only surmise from the data that this is what is happening at the core of this galaxy 3.8 billion ly away.   But, imagine what it must have looked like to see this star in its final death throws as it passed the black hole for the last time…

Till next time,

RC Davison

     There are jewels in the night sky and some of them are more fanciful than others. The spiral galaxy NGC 4921 is a case in point. Please click on the following links in the article for much higher resolution images. (Click for a larger image.)

      This beautiful barred-spiral galaxy resembles more a ghostly cosmic jelly fish than the typical spiral galaxy you may think of like the Whirlpool galaxy (M101) below:

     You’ll notice immediately that NGC 4921 is missing the well defined spiral arms seen in the Whirlpool. There is structure there, but it is much more subtle.  You do see a dark swirl of dust around the core, accented with bright blue stars that are forming along this band.  And, you can see the bar that extends across the nucleus of the galaxy as well as some spiral structure to the arms.

     To me, what is most remarkable about this galaxy is that the white gossamer cloud is not dust but stars – billions and billions of unresolved stars spread very uniformly around the galaxy.  In a well defined spiral galaxy we don’t get the same impression of the vast number of stars contained within because they are clumped together in the arms.  NGC 4921 and the Whirlpool galaxies are roughly the same size (about 200,000 lightyears verses 175,000 lightyears across), so comparing the two galaxies gives a good sense of how many stars are condensed into the arms.  It is interesting that this type of galaxy is termed an “anaemic spiral” because of the uniform distribution of stars.

      The galaxy is located about 320 million lightyears away in the galaxy cluster known as the Coma Cluster or alternatively Abell 1656 in the constellation Coma Berenices.  If you look closely at the image you will see thousands of galaxies scattered about NGC 4921 and even behind the nebulous galaxy.  Some are part of the Coma Cluster, while others extend much further beyond it.  This annotated image below (Click for a larger image.) shows highlights some of the details contained in this amazing image.

     Check out the Hubble website for more information, images and several short videos that will give you more in-depth information about this beautiful jewel of the night sky.   Enjoy the wonders of the Cosmos!

Till next time,

RC Davison