Shhh! Don’t wake the sun

Contrast these views of the nearly spotless sun on July 16-17, 2014 with a picture taken about two weeks earlier (below). Credit: Giorgio Rizzarelli

Who doesn’t enjoy a nap on a lazy summer afternoon? That’s what the sun’s been up to past few days. Instead of a steady parade of sunspots, it put its pencils away and went to sleep. For a time on July 17 not a singe magnetic blemish marred the entire Earth-facing hemisphere. The last time that happened was nearly 3 years ago on Aug. 14, 2011.

Ten groups including three visible with the naked eye dot the sun on July 8, 2014. Credit: NASA

The solar blank stare lasted but a day; by the 18th two small groups emerged. Today three little spot clusters have emerged but again, they’re on the small side.

I think the reason the sun looks so stark is that only two weeks ago nearly a dozen sunspot regions freckled the disk including three visible with the naked eye with a safe solar filter.

These ups and downs aren’t unusual unless this downturn continues for weeks. Expect more bubbles of magnetic energy to rise from beneath the glaring surface of the sun called the photosphere and spawn fresh groups soon. Because we now have eyes on the farside of the sun courtesy of the dual STEREO solar probes, we know the complete story. There are at least seven spotted regions in hiding there today.

Sunspot numbers are plotted for the last three solar cycles through the present. The double peak of the current cycle is shown. Credit: NASA

Sunspots and flares peak approximately every 11 years. We’re still riding the roller coaster near the top of the arc after the most recent solar maximum in late 2013. Some maxima are strong, others weak. The current max – Cycle 24 – is the weakest since Cycle 14 in February of 1906 and one of the wimpiest on record. Occasionally a cycle will have two peaks like the current one. The first peak occurred in Feb. 2012 and the second just this past June. What makes Cycle 24 even more unusual is that the second peak is higher than the first – the first time this has ever been recorded. Like people, every maximum has a personality of its own.

Doug Bieseker of the NOAA Space Weather Prediction Center has analyzed historical records of solar activity and he finds that most large events such as strong flares and significant geomagnetic storms typically occur in the declining phase of solar cycles—even weak ones, so don’t give up hope for some great auroral displays ahead.

A coronal mass ejection blew off on the farside of the sun early this morning July 20. It appears to envelop Jupiter, but the planet is 490 million miles in the background. SOHO uses an occulting disk to block the brilliant sun. Credit: NASA/ESA

The sun’s got a buddy this week – Jupiter! We can’t see the planet from the ground because it’s swamped by solar glare, but the Solar and Heliospheric Observatory (SOHO) has a great view from space. Watch the sun approach from the right and pass the planet over the next few days. After the 24th, Jupiter will move into the morning sky.

Huge sunspots scar the sun this week

Ten groups including three visible with the naked eye protected with a safe filter dot the sun today. Photo by the Solar Dynamics Observatory (SDO) taken at 8 a.m. CDT today July 9. Credit: NASA

A trio of impressive sunspot groups are parading across the sun’s face this week. Regions 2108, 2109 and 2110 are all closely-spaced and near the center of the disk today. All three require nothing more than a pair of eyes and a safe solar filter to view.

The sun seen through a standard 200mm telephoto lens and solar filter this morning gives you an idea of how the big sunspot groups look to the naked eye. Credit: Bob King

I took a look through my handy #14 welders glass this morning and saw 2110 distinctly; the other two groups blended into a single ‘spot’ at first. Looking closely I could barely split them into two separate dots. The view was spectacular at 30x in my little telescope with a total of ten sunspot groups and lots of fine detail in the three biggest.

Given high sunspot counts, the chance for flaring has been increasing in recent days. Today there’s a 75% chance for moderately strong M-class flares and 20% chance for the most powerful X-class variety.

Safe solar filters come in several varieties of optical / coated plastic and glass. Click to see ones you can purchase from Rainbow Symphony. Credit: Bob King

Curiously, none of the three biggies has shot off a large flare in the past day or two; they’re all currently stable. But the inconspicuous group 2113 fired off a beefy M6 flare only yesterday. It’s not expected to affect Earth, but because 2113 hides a complex magnetic field, future M-class or stronger blasts may be possible.

M6-class solar flare eruption from sunspot group 2113 captured July 8, 2014 at 11:24 a.m. by SDO. Credit: NASA

It seems like we’re due for aurora, so I’d be surprised if the current activity doesn’t lead to at least a minor storm soon. I’ll keep you updated.

Farewell Jupiter, hello moon!

The 2-day-old lunar crescent will shine low in the west-northwest tonight June 29, 2014. This view shows the moon about 30 minutes after sunset. Not far away – hidden by the tree – Jupiter makes its last stand. See below. Source: Stellarium

Tonight’s returning crescent moon will help us bid adieu to a planet that brought us through winter and spring to the doorstep of summer.

Jupiter’s put on a great show in Gemini this year. We’ve watched the nightly ballet of its four bright moons, pondered the shrinking of the Great Red Spot (how small it will get nobody knows) and witnessed the planet in many fine conjunctions with the crescent, quarter, gibbous and full moons.

That’s a lot of visual delight, but being one of the brightest planets, Jupiter rarely fails to please. Tonight you might see it for the last time this season using the moon as your guide. Face west-northwest about a half-hour after sunset. With binoculars, sweep the sky about 12 degrees to the right and below the crescent moon. Can you see it with your naked eye?

With a clear view to the west-northwest tonight, the moon will help you find Jupiter one last time. The map shows the sky 30 minutes after sunset from the central U.S. Jupiter lies about 12 degrees – a little more than a horizontally-held fist at arm’s length – to the right and below the moon. Use binoculars first and then see if you can spot it without optical aid. Source: Stellarium

No planet escapes the glare of the sun. The apparent movement of the sun across the sky caused by Earth’s revolution around it means that sooner or later our driven star catches up with the slower-orbiting planets that lie beyond the Earth. Indeed, the sun’s been gaining ground on Jupiter ever since January 5. On that date, the planet was at opposition, rising at sunset and remaining visible until the next morning’s sunrise. The very next day the sun gained 4 minutes on it and hasn’t stopped since.

Jupiter’s now (almost) hopelessly lost in bright evening twilight. It will still roast in the BBQ glow of the sunset until July 24 when it passes just a fraction of a degree north of the sun in conjunction. For several days before and after that date we’ll get to see it in SOHO’s coronagraph, an instrument that blocks out the sun to reveal the solar corona, background stars and occasional comet and planet crossings.

Wow! On Aug. 18, days after Jupiter returns to view in the morning sky, it will pass only 0.2 degrees (1/3 the diameter of the full moon) from Venus in the constellation Cancer. Source: Stellarium

As the sun passes and leaves Jupiter behind, the planet re-emerges in the east in morning twilight in early August. And what a grand entry it will be! On August 18 Jupiter passes just 0.2 degrees from Venus in one of the year’s most spectacular conjunctions.

If you recall, Jupiter spent most of this year in the constellation Gemini beneath the bright ‘twin stars’ Castor and Pollux. On its return in August you’ll be struck by how far the planet has moved east along the zodiac. Ceaselessly orbiting the sun, Jupiter will have abandoned Gemini for the faint constellation Cancer the Crab. And so it goes, round and round and round.

Chance for auroras tonight June 21-22 / Comet Jacques approaches the sun

A large cloud of hydrogen gas called a filament erupts from the sun on June 19, 2014. We normally see these fiery gas clouds along the sun’s limb as pink flames. Here it shows in silhouette.

Welcome to the first day of summer! The new season’s first night may just bring us a blush of northern lights. A filament – another name a solar prominence except seen in silhouette against the sun’s bright disk – erupted from the sun’s southern hemisphere Thursday. Flung into space because of some magnetic disturbance, most of the material shot off to the northeast, but some was Earth-directed. It should arrive overnight and possibly set off a minor aurora storm.

A portion of a CME / filament eruption Thursday may spark auroras tonight and tomorrow night. This photo was  made with the coronagraph on the Solar and Heliospheric Observatory. Credit: NASA/ESA

NOAA forecasters are calling for a 25% chance of a minor storm for mid-northern latitudes tonight and a 20% chance Sunday night.

The picture above showing the coronal mass ejection was taken with the Solar and Heliospheric Observatory’s coronagraph, a special camera with an occulting disk that blocks direct sunlight so astronomers can see what’s going on around the sun. Photos taken today with the instrument show a new visitor – Comet Jacques. You can watch it enter the field of view at lower left.

There are faint hints of a tail in these 24 consecutive images compiled into an animation by Rob Kaufman.

Amateur astronomer Rob Kaufman compiled multiple still photos into a video showing the ‘blip’ on the move. It’s currently around magnitude 7, but once it passes the sun and moves into the morning sky next month, it may be bright enough to spot in binoculars. More on that as the time approaches.

Another erupting filament photographed late Friday night June 20 with NASA’s Solar Dynamics telescope.

Boom! Boom! Boom! A solar flare triple crown

Three X-class flares erupted in sunspot group 2087 over a 24-hour period on June 10-11, 2014. A portion of the coronal mass ejections from the eruptions may brush the Earth in the next few days. Credit: NASA

Move over California Chrome.  After delivering three X-class flares in two days, sunspot group 2087 wins the triple crown for solar eruptions. And the fun’s not over yet.

The large, complex sunspot region 2087, pictured today June 12 at 8:30 a.m CDT, kicked off three powerful X-class flares on June 10 and 11. More flares are expected from the group in the coming days as it turns toward the Earth. Credit: NASA

Between it and two other spotted regions (2080, 2085) there’s a 60% chance for moderate M-class flares and 30% chance for more X-flares through Saturday. Plus, it turns out that part of the blast from 2087′s double-X flare is whooshing its way toward Earth right now.

Look at all the sunspots! Skywatchers with safe solar filters have a bounty of observing opportunities this week. Catch the big groups 2080 and 2085 (far right) before they rotate over to the sun’s other side. Credit: NASA

Most of the solar plasma blasted sideways off the sun after the eruptions but not all. NOAA space weather forecasters now predict a 20-25% chance of minor auroral storming overnight tonight through Saturday. With each day that passes, region 2087 inches closes to the center of the sun, where it will face Earth more directly, improving the outlook for auroras in the wake of new flares.

New sunspot group enters the stage with guns a-blazing

If ever an “X marked the spot”, this ‘x’ is it. It’s the first of a pair of x-ray flares that popped this morning at 6:42 a.m. CDT in sunspot region 2087. Photo taken in extreme ultraviolet light by NASA’s Solar Dynamics Observatory. Credit: NASA

Sunspot region 2087 announced its arrival on the sun’s southeastern limb today with a real show of firepower. Like a double-barreled shotgun, the group blasted off an X2.2 flare at 6:42 a.m. CDT followed 70 minutes later by an X1.5 at 7:52.

The second flare, an X1.5, peaked around 7:57 a.m. CDT today June 10. Credit: NASA

Although neither was directly in line with Earth, ultraviolet light from the explosions caused a wave of ionization in our planet’s upper atmosphere that affected radio propagation over Europe. Images from NASA’s STEREO solar spacecraft show a coronal mass ejection moving off to one side of the side. It’s not expected to affect the Earth.

The lively sunspot group 2087 has just rotated around the southeastern limb of the sun. 2080 and 2085 are both magnetically complex groups that could spawn M-class flares of their own. Photo taken this afternoon at 1:15 p.m. CDT. Credit: NASA / SDO

Interestingly, the ACE spacecraft, which measures changes in the direction of the magnetic field bundled with the solar wind, dipped south right around the time of the flares. While the two events may be unrelated, anytime the field tilts south, conditions are opportune for the sun’s particle wind to hook into Earth’s magnetic field and possibly fire up auroras.

A large coronal mass ejection, sparked by the double-flare photographed at 9:39 a.m. today by NASA’s STEREO-B spacecraft, expands away from the sun. Credit: NASA

Though it may not be related, the magnetic direction of the wind has been rapidly shifting from north and south all morning and afternoon. Solar astronomers had expected to see flares from sunspot regions 2080 and 2085. Both have complicated delta class magnetic fields ripe with the potential for sparking solar storms. Both also squarely face the Earth. Should an X-class flare erupt in either, the material ejected could wind up producing a geomagnetic storm and accompanying northern lights later this week. So far, they’ve been ‘quiet’ today.

There’s also a chance the plasma cloud released by the X-flare blasts could strike a glancing blow to Earth’s magnetic field; the new group may also continue to produce flares as it rotates into a favorable, Earth-facing position on the sun’s disk.

Surprise aurora puts on Sunday morning show

Sallie Carlson of Lutsen, Minn. took this photo this morning June 8, 2014. She reported aurora visible overhead and rays bright enough to overtake the light of the gibbous moon. Copyright: Sallie Carlson

Ouch! Missed a great aurora this morning. The potential was there late yesterday afternoon when the magnetic field bundled with the solar wind tilted south and hooked into Earth’s magnetic domain. Activity increased but nothing was visible here in Duluth up till midnight. Moonlight may have washed out any early, low aurora present.

That all changed sometime around 1 a.m. right about the time I entered dreamland. Others who stayed up late reported lots of red rays visible even from moderately light-polluted locations:

“1:45 am. slight calm after 45 mins of intense displays with lots of red showing even in my semi-urban location,” said reader Paul Contant of Penticton, British Columbia, Canada.

Bar chart showing the jump in the Kp index overnight. A southward tip in the interplanetary magnetic field (which originates on the sun) and increase in the speed of the solar wind were responsible for the display. Activity is ramping down this morning but there’s still a chance for auroras tonight. Credit: NOAA

Auroras were seen all the way to the zenith throughout the morning hours as the Kp index, an indicator of magnetic activity high overhead, surged to ’6′ spawning a G2 moderate magnetic storm.

An all-sky aurora with green and purple curtains early starting up about 1:30 CDT and going until dawn as seen from southern Alberta, Canada. The Big Dipper is above the Barn. The purple color is from blue scattered sunlight hitting the red tops of the auroral curtains. Details: 16-35mm lens at f/3.2, 20 seconds at ISO 1600. Copyright: Alan Dyer

This morning’s aurora was a complete surprise. Mostly quiet conditions were expected and still are. NOAA’s space weather center calls for only a small chance for auroras tonight but you better believe I’ll be on the lookout. Let us know if you see anything, too.

Lunar crescent returns – Mercury and Jupiter follow mother sun into twilight

The crescent moon will be near Mercury tonight (May 30) and below Jupiter tomorrow night. The map shows the sky facing northwest about 40 minutes after sunset. Stellarium

Nice to see to moon back in the evening sky just in time for the weekend. The 2-day-old slender slip of a thing makes an appearance about 40 minutes after sunset about 7 degrees (not quite one outstretched fist) to the lower left of Mercury.

Keen-eyed observers with haze-free skies may spot the planet without optical aid, but I’m guessing it will take a pair of binoculars. Mercury has faded in the past few weeks and will soon disappear in the sunset glow not to return again for northern hemisphere skywatchers until mid-July before dawn.

You’ve probably noticed that Jupiter’s been dropping lower and lower in the west and now sets near the end of evening twilight. The hefty planet and skinny moon will line up for one last easily visible conjunction tomorrow evening. By next lunar crescent (June 29), Jupiter will be difficult to pick out from the twilight glow.

In this map I’ve removed the atmosphere and added the ecliptic, the path taken by the sun, moon and planets across the sky. The sun’s day-by-day travel to the east is a reflection of Earth’s revolution around the sun. Its movement outpaces that of the outer planets, so it gradually catches up and then passes them one after another. When near the sun, a planet can’t be seen, but when the sun has left it behind, the planet reappears to the right or west of the sun in the morning sky to start the cycle all over again. Stellarium

Because sun, planets and moon all follow the same general path across the sky called the ecliptic, they inevitably pass near the sun for at least a few weeks every year (more often for the inner planets Mercury, Venus and the moon). Solar glare renders them invisible for a time until they pop back into view in the morning sky at dawn and begin the next cycle of visibility.

Polka dots and sunbeams a solar observer’s dream

Sunspots speckle the sun like polka dots in this photo taken early this morning by NASA’s Solar Dynamics Telescope (SDO). The largest spot (right of center) belongs to sunspot group 2055. The view is very similar to that seen through a typical amateur telescope equipped with a safe solar filter. Sunspots are regions where magnetic energy is concentrated on the sun’s surface. Credit: NASA

For a change it was wonderful to show people a heavily speckled sun at Astronomy Day festivities yesterday. If it’s clear – rare enough in itself – sunspots are usually little more than crumb-sized and look like flecks of dirt or dust through the eyepiece.

Kids and adults eager to see sunspots queue up at Jim Schaff’s dual telescopes, which showed the sun in both visible light and deep red hydrogen-alpha. Schaff, of Duluth, is at left. Credit: Bob King

But this week the past few days, the sun’s been showing off a half dozen spots as large or larger than the planet you toil upon. There are currently at least 8 numbered sunspot groups. One of them, the leader spot in group 2055, was easily seen through a #14 welder’s glass this morning.

A C4-class flare in sunspot region 2055 early yesterday evening May 10 glares in this photo made in ultraviolet light by SDO. More flares up to M-class are possible from this region in the coming days. Credit: NASA

To be visible with the naked eye (with filter), a sunspot or sunspot group has to extend some 31,000 miles (50,000 km) or about 4 times the diameter of Earth. While enormous, about 2-3% of sunspots and sunspot groups or about 100 per 11-year solar cycle can be seen by a dedicated solar observer, proving you don’t need a telescope to follow the general trend of the 11-year sunspot cycle.

The first drawing of sunspots was made by English monk John of Worcester in 1128 A.D.

The first written records of sunspots come to us from the Chinese as long ago as 800 B.C. Court astrologers in China and Korea kept tracks of spots because they believed they foretold important events. The earliest known drawing of sunspots was made almost 500 years before the invention of the telescope by English monk and chronicler John of Worchester. On Dec. 8. 1128 A.D., Brother John wrote:

“…from morning to evening, appeared something like two black circles within the disk of the Sun, the one in the upper part being bigger, the other in the lower part smaller. As shown on the drawing.”

First photo of the sun using the daguerrotype process taken by Fizeau and Foucault on April 2, 1845. Though fuzzy, you can still make out sunspot groups and the basic dark umbra-lighter penumbra structure of the spots. Credit: ESA

His sighting was followed five days later by a red aurora recorded over Korea. The two may have been related.

As long as we’re talking firsts, the first successful photograph of the sun and sunspots was made on April 2, 1845 by French physicists Louis Fizeau and Leon Foucault on daguerrotype with an exposure of 1/60 of a second. It looks pretty rough but photography only improved from there.

Nowadays, anyone with a safe solar filter for either naked eye or telescope use can see what the sun’s up to. Solar telescopes in orbit and on the ground photograph the sun almost continuously. NASA’s dual STEREO orbiting solar probes even show us what’s happening the side facing away from Earth.

A prominence eruption blasted a CME or coronal mass ejection off the northeast side of the sun very early this morning. It’s not Earth-directed. This photo was taken by the Solar and Heliospheric Observatory (SOHO) which uses a disk to block direct sunlight. Credit: NASA/ESA

We not only want to learn more about how the sun works, but we’re justifiably concerned about its storms and how they affect our planet.

March monster flare gives NASA an eyeful

A up-close view of the March 29 X-1 flare taken by NASA’s IRIS spacecraft. Flares are colossal explosions that occur when strong magnetic fields – often over complex sunspot groups –  get twisted and then reconnect, releasing vast amounts of stored energy. Credit: NASA

On March 29 this year, sunspot group 2017 unleashed a powerful X1-class flare seen by more telescopes on Earth and in space than any other flare in history.

Four different NASA spacecraft and one ground-based observatory captured photos and data of the solar storm in multiple wavelengths of light. Fortuitously, three of them had been aimed on the group a day in advance in anticipation of a possible eruption.

Views of the flare in three different wavelengths of ultraviolet light made by NASA’s Solar Dynamics Observatory (SDO). The big spikes at left show that the flare was so intense it saturated the instrument’s detector. Credit: NASA

“This is the most comprehensive data set ever collected by NASA’s Heliophysics Systems Observatory,” said Jonathan Cirtain, project scientist for Hinode at NASA’s Marshall Space Flight Center.

Different telescopes shoot at different resolutions. SDO is optimized for taking full-disk photos of the sun. Enlarging the spot group where the flare occurred results in a blurry image (left). At right, the Dunn Solar Telescope provides a much more detailed view. The white patch is the flare in near-visible light. Credit: NASA (left) and NSO

“Some of the spacecraft observe the whole sun all the time,” added Cirtain, “but three of the observatories had coordinated in advance to focus on a specific active region of the sun. We need at least a day to program in observation time and the target – so it was extremely fortunate that we caught this X-class flare.”

In NASA’s RHESSI space telescope, which records extreme temperatures on the sun, the flare appears as a series of three hot spots (purple) superimposed on the IRIS image. The two at left are near the surface; the other high above. Credit: NASA

The battery of instruments involved included three NASA orbiting telescopes – the Interface Region Imaging Spectrograph (IRIS); Solar Dynamics Observatory (SDO); Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI); the Japanese Aerospace Exploration Agency’s Hinode; and the National Solar Observatory’s Dunn Solar Telescope located at Sacramento Peak in New Mexico.

A nice summary of observations made by all the telescopes of the March 29 flare

Instruments on the observatories are planned so that each shows a different aspect of the flare at a different heights above the sun’s surface and at different temperatures. Together they can provided a comprehensive 3D view of one of nature’s most powerful blasts.

The images and video record flare material extending from the solar surface called the photosphere (literally ‘sphere of light’) to more than 3,000 miles high (4,800 km) – well beyond the top of the chromosphere, the lowest level of the sun’s atmosphere.

Cutaway showing the different layers of the sun’s atmosphere. Credit: NASA

Chromosphere means ‘sphere of color’ and comprises the realm of the beautiful flaming red prominences see during total solar eclipses. Temperatures there are hotter than the sun’s 10,000-degree F surface, rising from 11,000 degrees to about 36,000 degrees. Hydrogen gas, what the sun’s mostly made of, glows a deep red at these toasty temps.

Once you reach about 1,250 miles (2,000 km) the chromosphere transitions to the much more extensive solar corona. It’s here that the solar wind originates, that stream of subatomic particles – electrons and protons – blown into space at many miles a second. The violence of solar flares can also blast material out of the corona as a coronal mass ejection.

Flares affect all layers of the sun’s atmosphere. With awesome amounts of data in hand from the March 29 solar storm, scientists are now hard at work teasing out a more detailed picture of how a flare gets started and where it goes from there.