Vast Magnetic Canyon Opens up on the Sun — Choppy Space Weather Incoming?

As the sun dips into extremely low levels of activity before the current cycle’s “solar minimum”, a vast coronal hole has opened up in the sun’s lower atmosphere, sending a stream of fast-moving plasma our way.


To the untrained eye, this observation of the lower corona — the sun’s magnetically-dominated multi-million degree atmosphere — may look pretty dramatic. Like a vast rip in the sun’s disk, this particular coronal hole represents a huge region of “open” magnetic field lines reaching out into the solar system. Like a firehose, this open region is blasting the so-called fast solar wind in our direction and it could mean some choppy space weather is on the way.

As imaged by NASA’s Solar Dynamics Observatory today, this particular observation is sensitive to extreme ultraviolet radiation at a wavelength of 193 (19.3 nanometers) — the typical emission from a very ionized form of iron (iron-12, or FeXII) at a temperature of a million degrees Kelvin. In coronal holes, it looks as if there is little to no plasma at that temperature present, but that’s not the case; it’s just very rarefied as it’s traveling at tremendous speed and escaping into space.

The brighter regions represent closed field lines, basically big loops of magnetism that traps plasma at high density. Regions of close fieldlines cover the sun and coronal loops are known to contain hot plasma being energized by coronal heating processes.

When a coronal hole such as this rotates into view, we know that a stream of high-speed plasma is on the way and, in a few days, could have some interesting effects on Earth’s geomagnetic field. This same coronal hole made an appearance when it last rotated around the sun, generating some nice high-latitude auroras. predicts that the next stream will reach our planet on March 28th or 29th, potentially culminating in a “moderately strong” G2-class geomagnetic storm. The onset of geomagnetic storms can generate impressive auroral displays at high latitudes. Although not as dramatic as an Earth-directed coronal mass ejection or solar flare, the radiation environment in Earth orbit will no doubt increase.

The sun as seen by the SDO’s HMI instrument on Saturday, March 25. There is very little magnetic activity, apart from a small sunspot at the location of active region (AR) 2643 (NASA/SDO)

The sun is currently in a downward trend in activity and is expected to reach “solar minimum” by around 2019. As expected, sunspot numbers are decreasing steadily, meaning the internal magnetic dynamo of our nearest star is starting to ebb, reducing the likelihood of explosive events like flares and CMEs. This is all part of the natural 11-year cycle of our sun and, though activity is slowly ratcheting down its levels of activity, there’s still plenty of space weather action going on.


The magnetic loop containing hydrogen and nitrogen plasma evolves over 4 micro-seconds. Credit: Bellan & Stenson, 2012
The magnetic loop containing hydrogen and nitrogen plasma evolves over 4 micro-seconds. Credit: Bellan & Stenson, 2012

There’s no better method to understand how something works than to build it yourself. Although computer simulations can help you avoid blowing up a city block when trying to understand the physics behind a supernova, it’s sometimes just nice to physically model space phenomena in the lab.

So, two Caltech researchers have done just that in an attempt to understand a beautifully elegant, yet frightfully violent, solar phenomenon: coronal loops. These loops of magnetism and plasma dominate the lower corona and are particularly visible during periods of intense solar activity (like, now). Although they may look nice and decorative from a distance, these loops are wonderfully dynamic and are often the sites of some of the most energetic eruptions in our Solar System. Coronal loops spawn solar flares and solar flares can really mess with our hi-tech civilization.

A coronal loop as seen by NASA's Transition Region and Coronal Explorer (TRACE). Credit: NASA
A coronal loop as seen by NASA’s Transition Region and Coronal Explorer (TRACE). Credit: NASA

In an attempt to understand the large-scale dynamics of a coronal loop, Paul Bellan, professor of applied physics at Caltech, and graduate student Eve Stenson built a dinky “coronal loop” of their own (pictured top). Inside a vacuum chamber, the duo hooked up an electromagnet (to create the magnetic “loop”) and then injected hydrogen and nitrogen gas into the two “footpoints” of the loop. Then, they zapped the whole thing with a high-voltage current and voila! a plasma loop — a coronal loop analog — was born.

Although coronal loops on the sun can last hours or even days, this lab-made plasma loop lasted a fraction of a second. But by using a high-speed camera and color filters, the researchers were able to observe the rapid expansion of the magnetic loop and watch the plasma race from one footpoint to the other. Interestingly, the two types of plasma flowed in opposite directions, passing through each other.

The simulation was over in a flash, but they were able to deduce some of the physics behind their plasma loop: “One force expands the arch radius and so lengthens the loop while the other continuously injects plasma from both ends into the loop,” Bellan explained. “This latter force injects just the right amount of plasma to keep the density in the loop constant as it lengthens.” It is hoped that experiments like these will ultimately aid the development of space weather models — after all, it would be useful if we could deduce which coronal loops are ripe to erupt while others live out a quiescent existence.

It’s practical experiments like these that excite me. During my PhD research, my research group simulated steady-state coronal loops in the hope of explaining some of the characteristics of these fascinating solar structures. Of particular interest was to understand how magnetohydrodynamic waves interact with the plasma contained within the huge loops of magnetism. But all my research was based on lines of code to simulate our best ideas on the physical mechanisms at work inside these loops. Although modelling space phenomena is a critical component of science, it’s nice to compare results with experiments that aim to create analogs of large-scale phenomena.

The next test for Bellan and Stenson is to create two plasma loops inside their vacuum chamber to see how they interact. It would be awesome to see if they can initiate reconnection between the loops to see how the plasma contained within reacts. That is, after all, the fundamental trigger of explosive events on the Sun.

Read more in my Discovery News article: “Precursors to Solar Eruptions Created in the Lab

When Venus Transited the Sun

The Venus transit taken with my iPhone 3GS through a telescope eyepiece atop Mt. Wilson on June 5, 2012.
The Venus transit taken with my iPhone 3GS through a telescope eyepiece atop Mt. Wilson on June 5, 2012.

After the historic Venus transit and my involvement of the Astronomers Without Borders live webcast of the event from Mt. Wilson, I jetted off to Florida to give a talk at the 7×24 Exchange meeting in Orlando, so I had little time to post my transit photos on Now that my feet are (partially) back on the ground, I’ve found some time to upload them.

Interestingly, my favorite photos were taken using my trusty old iPhone 3GS through the eyepieces of random telescopes (pictured top), but here are some more from that awesome day.

For more, read my recent Discovery News articles based on the 2012 Venus transit:

Life on Mars? Only in The Sun.

In its haste to become the first newspaper to print the “NASA: Evidence of Life on Mars” headline, the UK’s Sun website caused a stir last week. Not only was this headline incorrect, it was a wee bit irresponsible.

For starters, no evidence for life has been found on the Red Planet. Second, NASA has not proclaimed such a discovery. In fact, The Sun riled the U.S. space agency so much, this headline prompted NASA spokesman Dwayne Brown to issue the following statement:

“This headline is extremely misleading. This makes it sound like we announced that we found life on Mars, and that is absolutely, positively false.”

So where did it all go so wrong?

This story stems from an astrobiology conference celebrating the 50th anniversary of the search for alien life. At this conference, findings by NASA’s Mars Exploration Rover Opportunity were reviewed. One of these findings was the tantalizing discovery of sulfates by the rover in 2004. Where there’s sulfates, water once existed. Where there’s water, life might have existed.

In an exciting twist to this discovery, scientists studying sulfate deposits on Earth (known as gypsum) were asked by scientists in the Mars Program to investigate terrestrial gypsum deposits more closely. Up until now, it was thought that gypsum contained no fossils, but on closer inspection it turns out that ancient gypsum deposits from the Mediterranean Sea (dated to about 6 million years old — when the sea was actually dry) are stuffed full of microscopic fossils of algae and phytoplanktons.

So, on Mars we have sulfates. On Earth we have sulfates (gypsum) full of fossils of aquatic microscopic life. If we know the terrestrial deposits of gypsum contain fossils of basic life forms, perhaps sulfate deposits on Mars would be a good place to start looking for basic ancient extraterrestrial life.

Of course, for the tabloid newspaper, these Martian sulfate deposits became “pond scum” and therefore “evidence” for life on Mars.

In actuality, the text of The Sun article wasn’t that misleading and actually did a good job of reporting the science (apart from the “pond scum” bit). Unfortunately, the title of the article let the rest of the article down, ultimately undermining the journalists’ work.

But, coming from the same publication that printed the silly “Pictures show life on Mars” article from 2008, the “Evidence for life on Mars” headline is pretty tame.

Now, time for the same news with a more appropriate headline by Irene Klotz on Discovery News: “Earth Fossil Find May Lead to Martian Discoveries

Thanks to reader Judy Mason for inspiring this post.