Feel the bliss, don’t miss Thursday’s partial solar eclipse

The solar crescents show how much Sun will be covered at maximum for various locations across the U.S. and Canada during the October 23rd (Thursday) partial solar eclipse. Credit: Jay Anderson

Doing anything Thursday afternoon? Have a few minutes to spareThere’s a partial eclipse of the Sun visible across much of North America and of Mexico you might like to catch. For observers in the U.S. and Canadian West the whole event begins and ends in the afternoon before sunset. Those living east of the Great Plains will see the Sun set while still in eclipse.

During a solar eclipse, the orbiting Moon passes between the Sun and Earth, completely blocking the Sun from view as shown here. In Thursday’s eclipse, the moon will pass a little north of a line connecting the three orbs, leaving a portion of the Sun uncovered. To view a partial solar eclipse, a safe solar filter is necessary. Credit: Wikipedia

Solar eclipses occur when the Moon glides between the Earth and the Sun, temporarily blocking it from view. Total solar eclipses get most of the attention because the Earth- Moon-Sun alignment is perfect. Like a snug lid on a pot, the Moon blanks out the Sun completely to create a dramatic spectacle of a black, fire-rimmed disk set in a plush solar corona.

Partial eclipses happen because the Moon’s orbit is tipped a few degrees to the Sun-Earth line. Most months, it passes north or south of the Sun and misses it completely. But during a partial eclipse, the Moon’s close enough to that line to partially block the Sun from view. Unlike a total eclipse, all phases of a partial eclipse are unsafe to view unless you use a safe solar filter or view it indirectly via projection.

Map showing times and percentage of the Sun covered during Thursday’s partial solar eclipse. Times are Pacific Daylight – add 1 hour for MDT, 2 hours for CDT and 3 hours for EDT. Interpolate between the lines to find your approximate viewing time. The arc marked A shows where the eclipse begins at sunset; B = Maximum eclipse at sunset and C = Eclipse ends at sunset. Credit: NASA, F. Espenak,with additions by Bob King

As you can see from the map, nowhere will this eclipse be total. Maximum coverage will happen in Nunavut Territory in northern Canada where the musk oxen might catch sight of a fat solar crescent 81% covered by the moon at sunset. The farther north you live in the U.S. or Canada, the deeper the eclipse. Northern U.S. states will see around 60% covered compared to 40% in the deep south.

In Duluth, Minn. for example, the eclipse begins at 4:21 p.m., reaches a maximum of about 65% at 5:33 p.m. and continues into sunset at 6:06 p.m. Since the sun will be low in the western sky from many locations, be sure to get a spot with a wide open view in that direction.To find out times and coverage for your city, use these links:

* U.S. Cities
* Cities in Canada and Mexico 

Some of the different kinds of safe solar filters available. They work by reflecting or absorbing most of the light from the Sun, allowing only a fraction through to the eyes. NEVER LOOK DIRECTLY AT THE SUN without one. Click photos for a supplier of eclipse glasses. Credit: Bob King

Solar filters come in a variety of styles from inexpensive eclipse glasses that use an optical polymer to glass welder’s filters to caps you place over the front end of a telescope. It’s important to use the correct kind – don’t stack a bunch of sunglasses and figure “it’ll do” or look through smoked glass. They still allow dangerous UV and infrared light to pass through and will mess up your retinas for life.

Because we’re on the heels of the eclipse, if you don’t already have a pair of eclipse glasses I recommend a #14 welder’s glass. It’s my favorite actually because it’s easy to stuff in a pocket and heavy-duty enough to take a few dings. You can pick one up for a few dollars at a welding supply shop. Only buy a #14 – lower numbers won’t cut it.

A piece of aluminum foil, a pin and a cardboard box are all you need to build a pinhole projector. The tiny hole creates a small image of the eclipsed Sun inside the darkened box which you place over your head.

Projection provides a fine alternative to using a filter. You can mount a pair of binoculars (or small telescope) on a tripod and project the Sun’s image on a sheet of white paper or build your own pinhole projector using the instructions above.

You can mount binoculars on a tripod, cover one lens with a lenscap and project the sun’s image safely onto a sheet of white cardboard. Credit: Bob King

If leaves still cling to your trees this season, the narrow spaces between the leaves act like natural pinholes and will cast multiple images of the eclipsed Sun on the ground below.

You can even place one hand atop the other and let the sun shine through the gaps between your fingers to see the eclipse. Low tech as it gets, but works in a pinch.

Here are some other things to watch for during the eclipse:

* If you live where half or more of the sun will be covered, you may notice a change in the quality of daylight. To my eye, the light becomes “grayer”. What do you see?

* Telescope users will see the mountains and crater rims along the moon’s edge as tiny bumps and projections against the brilliant solar photosphere. You’ll also notice how much blacker moon is compared to sunspots. Guess what? We’ve got a huge sunspot out there right now – Region 2192. Perfect for comparison!

Partially eclipsed sun just before sunset seen from Island Lake north of Duluth in May 2012. Credit: Bob King

*  Those living where parts of the eclipse happen at sunset will get an extra special view of the sun with a big bite out of it right sitting atop the southwestern horizon.

I wish you excellent weather – good luck!

 

Monster sunspot could stir up auroras

The sun photographed this morning by NASA’s Solar Dynamics Telescope at 11:30 a.m. CDT this morning October 18. Credit: NASA

Not today and not tomorrow, but a monster sunspot group rounding the eastern limb of the sun could spunk up the fall aurora season. Active region 2192 harbors a Jupiter-sized sunspot that’s just now visible with the naked eye using a safe solar mylar filter or #14 welder’s glass. I spotted it very close to the southeastern edge of the sun today. In the coming days, it will rotate into better view, making for an easy catch with the naked eye or small telescope. I can’t emphasize enough the importance of a safe filter. You can purchase one HERE for naked eye viewing or HERE for your telescope.

Coronal mass ejection shot out by flare activity in new sunspot group 2192 on October 14 before it even rounded the sun’s limb. Image from the SOHO coronagraph. Click for video. Credit: NASA/ESA

Even before the behemoth came into view, it spawned a brilliant coronal mass ejection on October 14 and several M-class medium strength flares. If we assume that the giant spot stays potent, the sun will rotate it around to face Earth in about 6 days. Flaring and other activity would then stream in our direction.

It will also spice up the partial solar eclipse next Thursday afternoon. Watch for the black limb of the moon to not only eclipse the sun but this sunspot too!

Update: Sunspot group 2192 unleashed an strong X-1 class flare around midnight Oct. 18-19. Any material it may have launched into space would have missed Earth by a wide margin because of the group’s position near the sun’s edge.

Nearby red dwarf star unleashes X100,000 superflare

The largest flare ever recorded on the sun, an X 45 event in November 2003, pales in comparison to the estimated X 100,000 flare seen on the red dwarf star DG CVn on April 23 by NASA’s Swift satellite. The sun image is an actual photo; the dwarf star flare an artist’s view. Credit: NASA

Sometimes big things come in small packages. Last April, DG CVn, a red dwarf star only one-third the size of the sun, cut loose with a flare 10,000 times more powerful than any solar flare ever recorded. The sun’s grandest was an X 45 on November 4, 2003 which happily was directed off its western limb away from Earth. Had it happened closer to the center of the solar disk, damage to satellite electronics and power grids on the ground might have been substantial.

NASA’s Swift mission detected a record-setting series of X-ray flares unleashed by DG CVn, a nearby binary consisting of two red dwarf stars, illustrated here. At its peak, the initial flare was brighter in X-rays than the combined light from both stars at all wavelengths under normal conditions. Credit: NASA’s Goddard Space Flight Center/S. Wiessinger

The superflare erupted from one or the other of two closely-orbiting red dwarfs in the constellation of Canes Venatici (abbreviated CVn) located beneath the handle of the Big Dipper. While only 60 light years from Earth, the two stars orbit each other only three times Earth’s distance from the sun which is too close for the Swift satellite to know which one did the deed.

At its peak the flare shot up to 360 million degrees F (200 million C) or 12 times hotter than the center of the sun. Despite its magnitude, the star is too far away to pose any harm to Earth. As to how a smaller, cooler dwarf could unleash such an energetic blast, we have two important leads.

The sun still has a lot pep left. This M7.3 (medium class) flare erupted along the sun’s western edge on October 2 as seen by the Solar Dynamics Observatory. It was not Earth-directed. Credit: NASA

Astronomers estimate DG CVn was born about 30 million years ago, which makes it less than 0.7% the age of the solar system. Like children, youthful stars are blessed with energy and show it through rapid rotation – DG completes one spin in just under a day or 30 times faster than the sun. The sun also rotated faster in its youth and may well have produced a few of its own superflares. Now it spins once every 27 days, fast enough to amplify magnetic fields to X-class strength but no match for the younger set.

Magnetic energy gets concentrated around sunspots or starspots in the case of DG CVn. In the turbulent environment, opposite polarities (north and south poles) can snap together and reconnect, releasing gobs of stored energy as a flare.

Flares are classified according to their energy output. The weakest – A,B and C-class – have almost no effect on Earth. M-class or medium flares accompanied by blasts of solar particles can cause radio blackouts and fire up northern and southern lights. The strongest are the X-class, which can lead to long-lasting radiation storms and nights-long auroral displays.

Aftermath of the X 45 flare in November 2003 clearly shows loops of solar gases outlining the powerful magnetic field rising above the sunspot group (not visible) below. Credit: NASA

At 5:07 p.m. EDT on April 23, the rising tide of X-rays from DG CVn’s superflare triggered Swift’s Burst Alert Telescope (BAT).

“For about three minutes after the BAT trigger, the superflare’s X-ray brightness was greater than the combined luminosity of both stars at all wavelengths under normal conditions,” noted Goddard’s Adam Kowalski, who is leading a detailed study on the event. “Flares this large from red dwarfs are exceedingly rare.”

Three hours later the system exploded with another weaker flare. More flares continued in a series for the next 11 days like aftershocks from an earthquake. Astronomers have observed the same phenomenon with the sun called “sympathetic flaring” where one explosion triggers another.

Stars delight the eye and make the Earth an abode for life, but don’t get too close. They’re scary.

 

How long would it take to drive to the sun?

My old Subaru achieved lunar orbit when the odometer hit 238,000 miles several years back. Credit: Bob King

I spend way too much time in the car, mostly on the job as a photojournalist. Every day, there are places to be at this time and that. Like many who drive around for a living,  I’ve accumulated a few miles on my vehicles.

Once, in an older Subaru, I achieved a one-time dream of reaching the moon. The odometer rolled past the 238,000 mile mark – just under the average lunar distance but easily within perigee range. I would have pushed the vehicle further, but the brakes seized up and soon after I sold the car. I recall it leaving the driveway on a flatbed like a patient being wheeled away to the emergency room.

The sun is some 387 times farther from Earth than the moon. Credit: Bob King

The years of driving it took to “get to the moon” got me wondering how long it would take to drive to the sun, which lies some 93 million miles (150 million km) from Earth or 387 times farther away than the moon.  According to the Guinness Book of World Records, the record vehicle mileage goes to a 1966 Volvo P-1800S with more than  2,850,000 miles (4,586,630 km). Owned by Irvin Gordon of East Patchogue, New York, the car is still driven daily.

A commercial jet flying at 550 mph would need 19 years to reach the sun. Credit: Bob King

While that trashes my record, it’s still only 3% of the way to the sun, a nice start but barely there. Instead, let’s drive non-stop at 60 mph (97 kph). How long would it take before we would complete our journey? An amazingly long time – 177 years. Strange, isn’t it? The sun seems so close because we can feel its warmth and watch it ripen our tomatoes. But it’s out there, w-a-y out there.

Even in a commercial jet flying at 550 mph (885 kph) it would still take 19 years. I’m afraid I just don’t have that kind of time or patience. Even the 5-hour trip to Hawaii from Los Angeles made me twitchy. The Helios probes, the fastest moving space vehicles ever, reached speeds of 157,000 mph as they orbited around the sun sensing the solar wind. At that rate, the sun could be reached in just 24.7 days.


Bill Nye demonstrates the distances between the planets.

How about a planet? Let’s choose picturesque Saturn, now low in the southwestern sky at dusk. Its average distance from the sun is 891 million miles (1.4 billion km) or 1,695 years in a car. That means if we started driving in 320 A.D. when ancient Rome still dominated the western world, we’d finally arrive today. Aw heck, I’d rather take a plane and get there in just 185 years.

Maps showing the planets and layout of the solar system give a false impression of sizes and distances. But you can hardly blame the creators. There’s just too much empty space between the planets compared to their tiny sizes to squeeze it all a useful diagram. Credit: NASA

Even in the solar system, never mind the stars, distances are so immense we can hardly comprehend them. If we reduced the sun to the size of a grapefruit, Earth would be a poppy seed 35 feet (10.7 m) away, Saturn a pea at 335 feet (102 m) and the nearest star system, Alpha Centauri, a pair of grapefruits 1,800 miles (2,900 km) away. There’s so much emptiness and so little stuff, it’s mind-boggling.

Twin solar storms may stoke auroras tonight Sept. 11-12

A CME or coronal mass ejection from the sun on September 9 is expected to pass Earth later today and possibly spark auroras tonight. Credit: NASA/ESA

(Click HERE for updates))

Two bursts of solar particles propelled by flares on September 9th and 10th are expected to arrive starting tonight and possibly touch off a moderate G2 geomagnetic storm. Translation: auroras may bloom in the next few nights!

A moderate M4 flare occurred early on September 9th followed by a more powerful X1.6 yesterday afternoon. Provided the magnetic field the particles come packaged in points in the right direction – south – these bursts have good potential for creating auroras tonight and again over the weekend.

A second, Earth-directed CME leaves the sun in the wake of the X1.6 flare on September 10th. Credit: NASA/ESA

The timing is good because the moon is past full and won’t be too bright. During a moderate storm, auroras are often seen across the northern tier of states and Canada. According to the latest NOAA space weather forecast, activity should kick up but remain shy of storm level from 9 p.m.-midnight Central Daylight Time tonight September 11th.

The brunt of the storm is expected from 1-4 a.m. tomorrow morning the 12th with effects lasting until 7 a.m.

This may only be the start of an even stronger storm anticipated Friday night and continuing into the weekend beginning from yesterday’s flare. That one blasted material directly toward Earth. Always a good omen for auroras.

Earth’s magnetic bubble, generated by motions within its iron-nickel core and shaped by the solar wind, is called the magnetosphere. It extends some 40,000 miles forward of the planet and more than 3.9 million miles in the tailward direction. Credit: NASA

As always with northern lights, keep in mind they’re fickle. Most of the time, Earth’s magnetic defense – a humongous, teardrop-shaped bubble of magnetism called the magnetosphere –  acts as a bulwark against strong solar winds, letting them slide by harmlessly. We’ll see what happens on this round, but I’m optimistic.

The Earth weather forecast for my locale is mostly clear tonight, so I’ll be monitoring the sky. Stop back later for an update.

* UPDATE 9 p.m. CDT: Quiet so far. Auroras still holed up in Hudson Bay and Quebec. The magnetic field direction of the arriving wind from the sun shows a lot of variation (see ACE satellite plot, topmost graph showing Bz) rising and falling from positive to negative. Negative is good! A prolonged stay at -10 or lower increase the chance of seeing the aurora.

Hole-y auroras possible tonight Aug. 30-31 / Jupiter returns

The dark opening at the center of the sun’s disk, seen here in ultraviolet light, is a coronal hole photographed on August 28 by the Solar Dynamics Observatory. Holes are ports through which high speed particles from the sun can pour freely into space unconstrained by solar magnetic fields. Credit: NASA

Sometimes it doesn’t take a big solar storm to incite an aurora. Often enough, a hole will do. Midweek, a blizzard of electrons and protons called a coronal mass ejection arrived in Earth’s vicinity, snuck past our magnetic defenses and painted northern skies for several nights in a row with glowing curtains and rays.

Yesterday night, a coronal hole did the same. Coronal holes are openings in the sun’s otherwise ‘locked down’ magnetic canopy. In the photo above, swirls of magnetism form closed loops over most of the sun’s lower atmosphere, keeping the bubbling sea of solar plasma (charged particles) at bay.

Enhancements in the solar wind either from solar storms (CMEs) and coronal holes send a thin soup of electrons and protons into space. If a batch happens to have a southward-pointing magnetic field, it can open a crack in Earth’s northward-pointing field and stimulate oxgen atoms and nitrogen molecules to glow in the upper atmosphere. The aurora is concentrated in two ovals, one hovering over each magnetic pole. Credit: Todd Salat

The sun’s so hot that it energizes and accelerates bits and pieces of itself – electrons and protons – to speeds high enough to escape its gravitational pull. Astronomers call the gust of departing particles the solar wind. Typical speeds hover around 250 miles per second (400 km/sec), but winds leave coronal holes unchecked and can blast into space at up to 500 miles per second (800 km/sec).

When the tempest arrives at Earth and harbors south-pointing magnetism, it links into Earth’s north-pointing magnetic field, sending electrons and protons at high speed down the planet’s magnetic field lines into the upper atmosphere to spark auroras.

Coronal holes are holes where the sun’s magnetic field where the solar wind can escape at high speed. Credit: NASA

NOAA space weather forecasters expect the effects of coronal holes to continue tonight and linger through Monday. Peak possibility for northern lights tonight happens between 10 p.m. and 1 a.m. CDT. Sometimes a particular hole can persist for several solar rotations causing repeat auroras every 27 days.

Stay tuned to Ovation aurora to see if any auroras are dropping south toward your region tonight.  I’ll be in touch.

Jupiter (top) and Venus in bright twilight on August 27, 2014. Credit: Bob King

The other morning while watching aurora I was happy to see that Jupiter had jumped back into the sky. It cleared the trees during twilight and was followed a half hour later by Venus. Low elevation and wiggly air currents meant I couldn’t magnify it much, but at 64x but north and south equatorial belts were unmistakeable.

I always look forward to that first view of Jupiter after conjunction with the sun. We last saw the planet in June, quite a while back. Jupiter’s weather and cloud patterns constantly change. One never knows what to expect when it’s out of sight for a couple months – sometimes an entire equatorial belt can disappear! I’m hear to report that both are still intact.

Brief aurora Weds. Aug. 20-21 – maybe more overnight?

A low arc and dim green rays were topped by a red border in this photo taken around 11 p.m. CDT Wednesday night Aug. 20. Details: ISO 3200, f/2.8, 20mm lens. Credit: Bob King

Scandinavians were the lucky ones yesterday when auroras broke out during their nighttime. Here in the U.S. it was still afternoon. Auroras are mighty scarce in sunshine.

Tonight to my surprise, we had a brief display around 11 p.m. CDT.  An arc rose above Boulder Lake north of Duluth, Minn., where a group of naturalists and I spent the night at the telescope under a starry sky. At the sight of a few needle-thin rays, one in our group jumped in a canoe and paddled out into the lake for a better view.

More rays taken a few minutes after the first photo. The display was fairly quiet and reached to about 10 degrees above the northern horizon. Credit: Bob King

Not 15 minutes after it began, the arc and rays faded away, leaving only a faint, diffuse glow until fog settled in around midnight. The Kp index rose slightly during the evening, and the ACE satellite plot has shown a southward pointing Bz or solar magnetic field in Earth’s vicinity for many hours. This is often a good indicator of auroral activity on the way.

The show was subtle but no one was disappointed. Auroras are always welcome around here.

Aurora alert tonight Aug. 19-20 for northern U.S.

“Unbelievable,” says Reid Wiseman on seeing a spectacular auroral display from a window on the International Space Station this evening. This photo was tweeted out at 6 p.m. CDT. Credit: NASA/Reid Wiseman

The astronauts are seeing it from the space station. You and I just might too. A G2 moderate auroral storm kicked up this afternoon and early evening, and according to NOAA space weather experts, is expected to continue into the night.

Another shot of the aurora from orbit. “Never in my wildest dreams did I imagine this,” said Wiseman.

A coronal mass ejection (CME) caused by a filament or plume of hydrogen gas ejected a few days ago caused the sudden surge. The Kp index, a reliable indicator of magnetic activity in Earth’s upper atmosphere hit 6 earlier this evening. Should it ‘stick’ there, skywatchers in Canada and across the northern U.S. stand a good chance of seeing auroras tonight. Look to the north at the onset of night. I’ll keep you posted.

* Update 11 p.m. CDT: The Kp has plummeted to 2! That’s not good. It’s always possible that activity will shoot up again overnight. If you’re out tonight, take a look before going to bed.

Aurora alert tonight Aug. 2 / Rosetta comet update – striking new details!

A CME or coronal mass ejection erupting on July 30 may lead to a small display of northern lights tonight. Jupiter at right in this photo made with the coronagraph on the Solar and Heliospheric Observatory. Credit: NASA/ESA

Minor auroras might visit skies across the northern U.S. and southern Canada tonight, the result of a coronal mass ejection from an erupting filament on July 30. Filaments are clouds of hot hydrogen gas suspended in the sun’s lower atmosphere. They often stay put for days, but a little magnetic instability can launch one into space.

Material from the filament is expected to begin arriving this afternoon and continue into the evening hours. I’ll have an update later if auroras materialize. Meanwhile, keep an eye on the northern horizon when it gets dark tonight. Fortunately, the moon will only be a half and not wash out the sky.

Comet 67P/Churyumov-Gerasimenko at 621 miles (1,000 km) on August 1. Wow! Look at that richly-textured surface. This photo has higher resolution than previous images because it was taken with Rosetta’s narrow angle camera. The black spot is an artifact. Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

Rosetta sent two new pictures of Comet 67P/C-G from 621 miles (1,000 km) away that show striking new details including new artifacts. I’ve done some digging around and discovered that the dome-like features and ‘craters’ seen on the past couple photos are really artifacts due to image processing.

Wider-angle and lower resolution navigation camera photo of the comet. More artifacts are seen including what look like bumps or boulders. Credit: ESA

You’ll see a black spot (artifact) in the narrow-angle camera and another dome artifact in the Navcam photo. They’re generally pairs of bad pixels that get smoothed out in processing to look like real features on the comet’s surface. Those should go away once the spacecraft is close enough for the comet to fill the field of view.

Fire haze turns sun into big red ball

A towering cumulus cloud partially eclipses the setting sun Monday evening seen from Duluth. Haze from Canadian forest fires has returned to the region making for deep red suns around sunrise and sunset. Credit: Bob King

Smoke from fires in the Canada’s Northwest Territories continues to funnel down across Manitoba and into the U.S. Upper Midwest creating an artificial overcast of smoky haze. We’ve lost the blue clarity of our daytime sky; at night stars look much dimmer seem more distant.

If you’re a skywatcher, everything in the nighttime sky looks noticeably fainter, especially objects within 20° of the horizon. I feel as if I’m looking through gauze. The unusually pallid appearance of the sky from dinnertime onward might make you think the sun has already set until you realize it’s still out there in the west looking little brighter than the full moon.

Funny. Yesterday, when I took this picture, someone pulled up alongside my car and remarked at how amazing the moon looked. The strangely faint sun had thrown him off!

The full sun shortly before setting yesterday July 28, 2014. You might see three small sunspot groups – two to the right of center and a third a short distance within the sun’s left limb. Credit: Bob King

Fire smoke generally scatters away nearly all light from the setting sun except deep oranges and reds.

The haze is both good and bad when it comes to observing. We like a big red sun, but it’s tough sacrificing otherwise clear nights.

I shouldn’t complain. People farther north, where the smoke is heavier, have to breath it.

Keep watch on the moon the next few nights as it waxes from crescent to half. If you live where there’s forest fire smoke, chances are you’re in for some red moons too.