Of Sunspots and Solar Eruptions

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


Coronal Mass Ejection, June 7, 2011 - NASA SDO

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.


Sunspot with Earth reference.  Image courtesy of the Institute for Solar Physics

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.


Sunspot filaments showing relative velocities. - Image courtesy of the Institute for Solar Physics

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

Total Lunar Eclipse on December 20 – 21, 2010

Total Lunar Eclipse October 27, 2004 - Image by Fred Espenak

Look up!  Something to look forward to on the night of December 20 and into the early morning hours of the 21st.  The above image is the Moon in a total lunar eclipse as seen on October 27, 2004 from the United States.

      Lunar eclipses occur when the Earth, Sun and Moon are aligned with each other.  The Earth passes between the Sun and the Moon every month and that’s when we see a full Moon, but because the Moon’s orbit is tilted relative to the Earth, we only occasionally get eclipses.  Partial eclipses are more common as the Earth, Moon, and Sun are not quite aligned.  This eclipse on the 20th/21st will be a total eclipse as seen by people in the US.

       Check out Fred Espenak’s site for some great information on where and when the eclipse will be visible and what to expect.  Lunar eclipses are great to watch because you don’t have to worry about eye protection as you do when observing solar eclipses.  So sit back and enjoy!

       Here’s one more image from Forrest J. Egan at Digital Astro showing a time-lapse image of the lunar eclipse of October 2004. For more detailed information on this image go to the “Astronomy Picture of the Day” site.

Time-lapse image of the October 2004 lunar eclipse by Forrest J. Egan.

Till next time,

RC Davison

The Ever Active Sun

Take a look at this coronal mass ejection (CME) that the Sun set off on the 6th of December.

Filament breaking loose from the Sun - Image Courtesy of NASA

Be very happy that it wasn’t pointed in our general direction!  The filament extended over 435,000 miles (700,000 km). almost twice the distance between the Earth and Moon.

This video was taken by NASA’s Solar Dynamics Observatory (SDO)

Till next time.

RC Davison

Comet Hartley 2 and the International Space Station

Thanks to the efforts of Emily Lakdawalla of the Planetary Society, there is a really neat image that shows to scale the International Space Station next to the nucleus of comet Hartley 2.  (Note that this is a composite picture created using graphic manipulation software.)

Comet Hartley 2 and ISS - Image courtesy of NASA and Emily Lakdawalla

We have an appreciation for how big the space station is relative to the shuttle but seeing it next to the comet gives one a better sense of how big this small comet is.   Check out Emily’s blog, she does a great job posting the latest developments in planetary science.

Till next time,

RC Davison

The Heart of a Comet

NASA’s EPOXI mission, formerly the Deep Impact mission that launched an impactor into comet Temple 1 on July 4, 2005, has just sent back some amazing images of the nucleus of comet Hartley 2 as it flew by at a distance of about 700 km or about 420 miles.

Flyby views of Comet Hartley 2 - Image courtesy of NASA

You can easily see the jets of vapor being back-lit by the Sun at the ends of the nucleus, which is about 2 km, or about 1.2 miles long.  This is a great image that shows just where the large tail and coma, which surrounds the nucleus comes from.  Check out NASA’s site for EPOXI for more pictures and information.

This isn’t the first time we’ve gotten an image of a comet’s nucleus.  The picture below shows a nice comparison of the five comets we’ve peeked at.

5 Comets we've visited.  Image courtesy of NASA

Till next time,

RC Davison

The Pale Blue Dot

One more blog entry about Carl Sagan, or more precisely, the “Pale Blue Dot”.

The Pale Blue Dot - Image courtesy of NASAThe image on the left is the original “Pale Blue Dot” taken in 1990 by Voyager 1 as it headed out of the Solar System after its encounter with Saturn. NASA took this image in response to a request by Carl Sagan. It’s difficult to see the dot of Earth embedded in the ring of Saturn, but if you follow this link it is visible in the band on the right.

The image below on the left shows the Earth again from the vantage point of Saturn, this time taken by Cassini in 2006.  Lastly, the image on the right shows our home planet and moon as seen from Mars.  This image was taken by the Mars Global Surveyor in May of 2003.

Earth from Cassini - Image courtesy of NASAEarth from Mars - Image courtesy of NASA

The images are not all that impressive by themselves until you step back and realize just what you are looking at.  These are portraits of us—all of us—every human being, animal and plant living on this planet.  Everything that ever lived and died is contained on this blue orb.  We look a lot more fragile from these vantage points then we do when we go through our daily activities, don’t we?

With the recent anniversary of 9-11, it becomes more poignant, to me at least, that this is all we have.  There is no place we can go if things go from bad to worse here, be it global warming, asteroid impact, war or any of a hundred other things that could make Earth inhospitable.  We have no choice for long term survival but to work with each other to make it together on this “Pale Blue Dot”.  United, we can accomplish more for everyone than we can divided, at odds with each other, and the environment.

I think that this is the point Carl Sagan was trying to make with this beautifully simple image of our home planet.

Till next time,

RC Davison

New Bill To Study Asteroid Threat Is Now In Congress

Thanks to the efforts of California’s Representative, Dana Rohrabacher, a bill (H.R. 5587) has been introduced to Congress to study the threat of asteroid impacts on Earth.  The bill, titled: “To establish a United States Commission on Planetary Defense, and for other purposes.” is to spend not more than $2 million on establishing the commission for the purpose of:

    • (1) determine capabilities of United States Government entities, nongovernment organizations, foreign governments and entities, and international bodies to detect, characterize, and neutralize potentially dangerous Near Earth Objects (in this Act referred to as `NEOs’);
    • (2) identify and evaluate roles and responsibilities of United States Government entities to detect, characterize, and neutralize potentially dangerous NEOs;
    • (3) determine United States effectiveness in leading international efforts to detect, characterize, and neutralize potentially dangerous NEOs;
    • (4) build upon United States Government and foreign analyses, studies, and assessments, without duplicating efforts, to determine current and required NEO characterization and mitigation capabilities;
    • (5) identify and report on technology development required to provide effective planetary defense from dangerous NEOs; and
    • (6) investigate and report to the President and Congress on its findings, conclusions, and recommendations for corrective measures that can be taken to provide planetary defense.

While this is not funding for an actual search, it is funding that should allow us to understand what our capabilities are, what the threat is, and how to organize a united world-wide effort.  It’s a start!

The bill has been referred to the Committee on Science and Technology for review.   Check out the link above to view the complete bill, or this link for a more complete discussion.

Remember, every journey starts with one step…

Till next time,

RC Davison


Pan-STARRS, the Panoramic Survey Telescope & Rapid Response System, has begun operations with a working prototype – PS1 in Haleakala, Maui.  The final version of this effort – PS4 – will be four times as powerful as the prototype. A very impressive piece of hardware, indeed!  PS1 has a 1.8 meter primary mirror with a CCD array that has a total 1.4 gigapixels and covers a 3 degree field of view.  It will map over 6000 square degrees of the night sky each night!

The mission for PS1, besides being a proving ground for the complete system, is to monitor the Solar System for near Earth objects or NEOs.  These include asteroids and comets, and with Pan-STARRS’ ability to detect objects down to a magnitude of 24 (over 29 with some averaging of images taken over a few years) it is going to unveil an enormous number of NEOs — how about an estimated 100,000 asteroids/comets, along with 5 billion stars and 500 million galaxies over the next 3 years!

Pan-STARRS will also be doing active research in astronomy and cosmology in addition to scoping-out our local neighborhood – inside and outside our Solar System, where it will search for red and brown dwarf stars.   But, with regard to the search for Earth-crossing NEOs, Pan-STARRS will be our first line of defense in identifying threats.  We need to start developing plans to use this information should the worst case scenario occur.

For more details check out my article on Pan-STARRS on www.Brighthub.com.

Till next time,

RC Davison

Asteroid Watch

ORBITAL MANEUVERS is about a space shuttle’s crew’s struggle to survive a catastrophic asteroid impact on the Earth.  NASA has been monitoring near earth objects (NEO) for many years at varying levels of intensity and funding.  Recently though, it has come to light that with current funding levels available to NASA they will not meet the 2005 Congressional mandated goal of cataloging 90% of all NEO bigger than 460 feet across by 2020. They are on track with monitoring objects .6 miles across and have recorded over 11,000 objects of all sizes.

Consider that the size of Meteor Crater in Arizona is a mile wide, and was caused by an asteroid only 150 feet across – it would have wiped New York City off the face of the globe!  An object 460 feet across is going to be even more devastating – impact energy is 100 times more with a crater almost 2.5 miles in diameter.  The other disturbing statistic is that there are many more smaller asteroids out there than larger ones, so the odds of getting hit are that much greater.  Couple that with the fact that Jupiter just got hit by something big in July, which has the scientific community buzzing that statistically that should not have happened only 15 years after comet Shoemaker-Levy impacted the planet, and you should be getting the picture that there is a lot out there we don’t know about.  Limiting our search to objects 460 feet across can just give us a false sense of security, and leaning on statistics to determine how long we have before the next big one can be very misleading – and deadly.  What is the price tag going to be to pick up the pieces after an impact of a rock 300 feet across on a larger metropolitan center?  I’m sure it will be orders of magnitude larger than funding a comprehensive survey of all Earth crossing objects in our solar system down to the limit of our technology.  Which, I might add, should be an international effort.

With all that being said, NASA has a great site for learning about asteroids – Asteroid Watch.  Another related site that has a tremendous amount of information on NEO’s is the Near Earth Object Program from JPL/NASA.   Both of these sites are worth a look to help one understand just what might be out there and what we know about what has been cataloged.  Education is the key!

Till next time,

RC Davison