Spotless Sun: Blankest Year of the Space Age

Oct 01, 2008
Image: NASA

Astronomers who count sunspots have announced that 2008 is now the "blankest year" of the Space Age.

As of Sept. 27, 2008, the sun had been blank, i.e., had no visible sunspots, on 200 days of the year. To find a year with more blank suns, you have to go back to 1954, three years before the launch of Sputnik, when the sun was blank 241 times.

"Sunspot counts are at a 50-year low," says solar physicist David Hathaway of the NASA Marshall Space Flight Center. "We're experiencing a deep minimum of the solar cycle."

A spotless day looks like this (see image above).

The image, taken by the Solar and Heliospheric Observatory (SOHO) on Sept. 27, 2008, shows a solar disk completely unmarked by sunspots. For comparison, a SOHO image taken seven years earlier on Sept. 27, 2001, is peppered with colossal sunspots, all crackling with solar flares (right). The difference is the phase of the 11-year solar cycle. 2001 was a year of solar maximum, with lots of sunspots, solar flares and geomagnetic storms. 2008 is at the cycle's opposite extreme, solar minimum, a quiet time on the sun.

And it is a very quiet time. If solar activity continues as low as it has been, 2008 could rack up a whopping 290 spotless days by the end of December, making it a century-level year in terms of spotlessness.

Hathaway cautions that this development may sound more exciting than it actually is: "While the solar minimum of 2008 is shaping up to be the deepest of the Space Age, it is still unremarkable compared to the long and deep solar minima of the late 19th and early 20th centuries." Those earlier minima routinely racked up 200 to 300 spotless days per year.

Some solar physicists are welcoming the lull.

"This gives us a chance to study the sun without the complications of sunspots," says Dean Pesnell of the Goddard Space Flight Center. "Right now we have the best instrumentation in history looking at the sun. There is a whole fleet of spacecraft devoted to solar physics--SOHO, Hinode, ACE, STEREO and others. We're bound to learn new things during this long solar minimum."

As an example he offers helioseismology: "By monitoring the sun's vibrating surface, helioseismologists can probe the stellar interior in much the same way geologists use earthquakes to probe inside Earth. With sunspots out of the way, we gain a better view of the sun's subsurface winds and inner magnetic dynamo."

"There is also the matter of solar irradiance," adds Pesnell. "Researchers are now seeing the dimmest sun in their records. The change is small, just a fraction of a percent, but significant. Questions about effects on climate are natural if the sun continues to dim."

Pesnell is NASA's project scientist for the Solar Dynamics Observatory (SDO), a new spacecraft equipped to study both solar irradiance and helioseismic waves. Construction of SDO is complete, he says, and it has passed pre-launch vibration and thermal testing. "We are ready to launch! Solar minimum is a great time to go."

Coinciding with the string of blank suns is a 50-year record low in solar wind pressure, a recent discovery of the Ulysses spacecraft. The pressure drop began years before the current minimum, so it is unclear how the two phenomena are connected, if at all. This is another mystery for SDO and the others.

Who knew the blank sun could be so interesting? More to come...

Source: Science@NASA, by Dr. Tony Phillips

Explore further: India tests long-range missile from mobile launcher

add to favorites email to friend print save as pdf

Related Stories

Sun may determine lifespan at birth, study finds

Jan 07, 2015

Could the Sun be your lucky—or unlucky—star? In an unusual study published Wednesday, Norwegian scientists said people born during periods of solar calm may live longer, as much as five years on average, ...

Stars' spins reveal their ages

Jan 05, 2015

When you're a kid every birthday is cause for celebration, but as you get older they become a little less exciting. You might not want to admit just how old you are. And you might notice yourself slowing ...

Solar observatories face the prospect of being eclipsed

Dec 31, 2014

Motors whirred as a gleaming white dome slowly opened, allowing one of the premier solar telescopes in the world to track the magnetic fields and exploding flares of the sun. In a few hours, computers would translate that ...

Sun sizzles in high-energy X-rays

Dec 23, 2014

For the first time, a mission designed to set its eyes on black holes and other objects far from our solar system has turned its gaze back closer to home, capturing images of our sun. NASA's Nuclear Spectroscopic ...

Recommended for you

Going a long way to do a quick data collection

Jan 30, 2015

Like many a scientist before me, I have spent this week trying to grow a crystal. I wasn't fussy, it didn't have to be a single crystal – a smush of something would have done – just as long as it had ...

How are planets formed?

Jan 30, 2015

How did the Solar System's planets come to be? The leading theory is something known as the "protoplanet hypothesis", which essentially says that very small objects stuck to each other and grew bigger and ...

User comments : 2

Adjust slider to filter visible comments by rank

Display comments: newest first

Sirussinder
1 / 5 (3) Oct 02, 2008
The sunspots are on the other side of the sun.
Velanarris
not rated yet Oct 04, 2008
The sunspots are on the other side of the sun.


/facepalm

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.