Why the sun’s atmosphere is hotter than its surface
Why the sun’s atmosphere is hotter than its surface.
Why the sun’s atmosphere is hotter than its surface.
Why the sun’s atmosphere is hotter than its surface.
Amateur astronomer Thierry Legault traveled to Oman to not only photograph the Moon as it eclipsed the Sun on January 4, but also capture the International Space Station at the same moment. The image he took of both as they crossed in front of the Sun is amazing.
The monthly update of the Sun’s developing sunspot cycle was published tonight by NOAA’s Space Weather Prediction Center. You can see the newest graph below, which shows the slow rise in sunspots (blue/black lines) in comparison with the consensis prediction made by the solar science community in May 2009 (red line).
Not only does the Sun’s generally quiet trend continue, its activity took an additional plunge in December, dropping significantly from the previous month. This drop is probably due to the seven days of no sunspots that took place in mid-December.
All in all, we continue to head for the weakest maximum in two hundred years (see the graph on this page), which in the past meant very cold weather. Though scientists do not yet understand why the Sun does this or how these changes in solar activity influence the climate as much as they do, that this in now happening at a time when we have the technology to truly study it is an opportunity that must not be missed.

Though I have been saying that the Sun’s lack of sunspots the last two years suggests the possibility of that we might be facing an extended period without solar activity, I am not a solar scientist. Today, in a paper published today on the Los Alamos astro-ph website, a solar scientist says just that. Key quote:
One method that has yielded predictions consistently in the right range during the past few solar cycles is that of K. Schatten et al., whose approach is mainly based on the polar field precursor. The incipient cycle 24 [on-going right now] will probably mark the end of the Modern Maximum, with the Sun switching to a state of less strong activity.
After six blank days, the Sun is once again showing spots. As I have mentioned several times in 2010, this might be the last time the Sun is blank for years to come as it ramps up to solar maximum. However, don’t bet on it, as the Sun’s activity has been way below all predictions. The upcoming solar maximum might very well be the first in centuries with blank days interspersed throughout.
The SOHO spacecraft, in space monitoring the Sun since 1995, has discovered its 2000th comet!
Recent monitoring of the Sun’s brightness as it went from maximum to minimum in its solar cycle has found that, surprisingly, the changes in brightness across different wavelengths do not necessarily vary in lockstep. Key quote:
SIM suggests that ultraviolet irradiance fell far more than expected between 2004 and 2007 — by ten times as much as the total irradiance did — while irradiance in certain visible and infrared wavelengths surprisingly increased, even as solar activity wound down overall. The steep decrease in the ultraviolet, coupled with the increase in the visible and infrared, does even out to about the same total irradiance change as measured by the TIM during that period, according to the SIM measurements.
The stratosphere absorbs most of the shorter wavelengths of ultraviolet light, but some of the longest ultraviolet rays (UV-A), as well as much of the visible and infrared portions of the spectrum, directly heat Earth’s lower atmosphere and can have a significant impact on the climate. [emphasis mine]
How close to the Sun could we get?
Apropos my post yesterday on the sunspot cycle: A Dalton Minimum repeat is shaping up.
For the first time since October 10, and only the third time since August, the Earth-facing side of the Sun is blank, showing no sunspots. All told, 2010 has only been blank 13% of the time, for a total of 46 blank days, with only 12 days left in the year. These numbers contrast sharply with 2009, when the Sun was blank 71% of the time, or 260 out of 365 days.
It is very clear that the solar minimum is now over, and that the Sun ramping up to its next maximum. Blank days should soon cease (today might very well be the last for years), and the number of sunspots should continue to increase through approximately 2013, when astronomers now expect the maximum to peak.
It will be a weak maximum, however, likely accompanied with cold weather. At least, this has been the pattern for the last ten centuries, based on the best data that scientists have. When the Sun produces sunspots, the Sun gets hotter, and though that increase in radiation appears slight, it seems enough to warm the Earth’s climate. This is what appears to have happened around the year 1000, during what climate scientists call the Medieval Warm Period.
And when the Sun goes blank, or produces fewer sunspots, the Sun dims, and the Earth’s climate cools. This is what happened in the 1600s and 1700s, when the Little Ice Age gripped much of the Earth. It also happened in the first two decades of the 1800s, the last time the Sun produced as few sunspots as it is now, and when at least one year was called “the year without a summer”. Interestingly, that cold period at the beginning of the 1800s was also a period of intense volcanic activity, which threw a lot of dust and material into the atmosphere and thus helped contribute to the cooling of the Earth.
The last half of the 20th century, however, has not seen that much volcanic activity, which has made the atmosphere today clearer than any time in the past five decades. It has also been a time of increased solar activity, with most of the solar maximums peaking at generally higher numbers. No wonder scientists have detected evidence of a slight warming in the climate.
However, that warming appears to be ending, and it is doing so at the same time the Sun is going spotless. Though we don’t yet fully understand the mechanics of how these two events are linked, it behooves us to pay close attention. No climate prediction or computer model will mean anything if it does not.
Meanwhile, solar scientists remain unclear about the causes behind the solar cycle’s ebbs and flows. They have a reasonable idea that the cycle is caused by the Sun’s magnetic dynamo as it flips from one polarity to another. But why this happens is still subject to debate.
More importantly, it remains a complete unknown how long the next sunspot minimum will be. The Sun could spring back to life, as it did in the 1850s, producing lots of sunspots. Or sunspots might fade out for a few additional decades, as they did in the 1600s.
Sadly, based on the state of our science today, this is a question that probably no one will be able to answer — until we actually see it happen.
NOAA’s Space Weather Prediction Center today published its monthly update of the Sun’s developing sunspot cycle (see below). The graph shows the slow rise in sunspots (blue/black lines) in comparison with the consensis prediction made by the solar science community in May 2009 (red line).

As I noted last month, the rise in sunspots as we ramp up to the next solar maximum has definitely slowed, which indicates clearly that we are heading towards the weakest solar maximum in more than two centuries. And as I have noted repeatedly on this website as well as on the John Batchelor Show, that means very cold weather!
Progress! The University of Colorado and the Goddard Space Flight Center are forming a collaborative research center to study the Sun’s effect on the Earth’s Climate.
Then again, this is taking land ownership a bit too far: Spanish woman claims ownership of the Sun.
A do-it-yourself photo of the Sun that looks as good as any taken from space. And it’s art too!
NOAA’s Space Weather Prediction Center today published its monthly update of the Sun’s developing sunspot cycle, showing the slow rise in sunspots in comparison with the consensis prediction made by the solar science community in May 2009.

Unlike October graph, which showed a clear jump in sunspot activity, this November update shows that the rise in sunspot numbers has once again slowed down. As I’ve noted repeatedly, these numbers suggest that we are heading for the weakest solar maximum in two hundred years, far below predictions. And when that last happened, around 1810, it was called the Dalton minimum and the Earth experienced one of its coldest periods in many many decades.
After a three day stretch of blankness, a new sunspot has appeared on the Sun. The question remains: Have we now seen the last blank day for the just ending solar minimum?
The science is settled? According to one scientist’s data, the Sun actually brightened in visible wavelengths during the ramp down from solar maximum to minimum in 2004-2007 — the exact opposite to what was expected — while dropping in the ultraviolet four times more than predicted.
Yesterday NOAA’s Space Weather Prediction Center published its October monthly graph, showing the sun’s developing sunspot cycle in comparison with the consensis prediction made by the solar science community in May 2009.

Sunspot activity in September clearly jumped, though it still remains far below predictions. Prepare for the weakest solar maximum since the 1810s!
Note also that today the Sun is blank, with no sunspots, the first time this has happened since August. At that time I speculated that this might “be the last time the Sun will be blank for years as it continues to ramp up to its next solar maximum.” Obviously not. The question now is whether today will be the finale in blankness for this minimum.
Time to update the state of the Sun, as seen by satellite data (the last update was in July). The graph below, posted today by Physikalisch- Meteorologisches Observatorium Davos (PMOD), shows the variation in the Sun’s Total Solar Irradiance since 1978. I have added a blue horizontal line to show that even now, two years after the Sun reached the lowest point in its most recent solar minimum, it has still not brightened enough to equal the lowest point in the two previous minimums. (Note that if we included the minimum from 1976, the Sun would still be below that as well.)

Once again, the evidence is building that the Sun might be heading towards the weakest maximum seen to two centuries. And when that happened, things got very cold on Earth.

In a preprint [pdf] posted today on the astro-ph website, astronomers outline the discovery of a star more like a twin of the Sun than any previously discovered. The star is located in the galactic star cluster M67, 3000 light years away. The similarity is so close that the scientists even speculate that the Sun itself might have formed in this same cluster, 4.5 billion years ago. Key quote from paper:
The similarity of the age and overall composition of the Sun with the corresponding data of M67, and in particular the agreement of the detailed chemical composition of the Sun with that of M67-1194, could suggest that the Sun has formed in this very cluster. According to the numerical simulations by Hurley et al. (2005) the cluster has lost more than 80% of its stars by tidal interaction with the Galaxy, in particular when passing the Galactic plane, and the Sun might be one of those. We note that the orbit of the cluster encloses, within its apocentre and pericentre, the solar orbit. However, the cluster has an orbit extending to much higher Galactic latitudes, presently it is close to its vertical apex at z = 0.41 kpc (Davenport & Sandquist 2010), while the Sun does not reach beyond z = 80 pc (Innanen, Patrick & Duley 1978). Thus, in order for this hypothesis of an M67 origin of the Sun to be valid, it must have been dispersed from the cluster into an orbit precisely in the plane of the Galactic disk, which seems improbable.
The last sentences above refer to the different orbital inclinations of the galactic orbits of both the Sun and M67. M67’s orbital inclination is far steeper. While M67 is presently about 1350 light years (410 parsecs) above the galactic plane, the Sun’s orbit never takes it more than 261 light years above the plane.
One more point of interest: M67 is a well known object to amateur astronomers, located in the constellation Cancer.
Will wonders never cease? The sun actually does influence the climate, the powers-that-be admit at last.
Say goodbye to sunspots?
The Sun is spotless again. By this stage in the ramp up to solar maximum, such things should no longer be happening.
The Sun continues to show a reluctance to come out of its solar minimum. Today NOAA’s Space Weather Prediction Center published its monthly graph, showing the sun’s developing sunspot cycle in comparison with the consensis prediction made by the solar science community in May 2009. As you can see below, actual sunspot activity remains far below what was predicted by the red line.

As I noted when I posted the July and August graphs, the Sun’s ramp up to solar maximum continues to be far slower and weaker than predicted. After two hundred years of watching a vibrant and strong solar cycle, it appears increasingly likely that we are heading towards some quiet time on the Sun.
A preprint paper published today on the Los Alamos astro-ph website shows further evidence of the decline in the strength of the Sun’s magnetic field over the past ten years. Extrapolated into the future, this data also suggests that the next solar maximum will be the weakest in 200 years, and that the solar maximum after that will have no sunspots at all. You can download the paper here [pdf].
After a short four day stretch with no sunspots — the first time in months — two new sunspots appeared today. It is very possible that this will be the last time the Sun will be blank for years as it continues to ramp up to its next solar maximum.
For the first time in months, the Sun is blank, with no sunspots. This lull should be very temporary, and might very well be the last time we see the Sun so quiet for a long time, as it ramps up to its next solar maximum (even if that solar maximum is very weak).
Speaking of the Sun, on August 14 it unleashed the first solar radiation storm of new solar cycle 24.