Ever seen a lunar eclipse from Mercury? Me neither … till now

Wednesday’s lunar eclipse photographed by NASA’s MESSENGER spacecraft at Mercury

As millions of us awoke at dawn and trundled outside to watch the total lunar eclipse this week another set of eyes was keeping tabs from afar. 66 million miles away, NASA’s MESSENGER spacecraft turned its camera toward Earth to capture several images of the moon disappearing into our planet’s shadow. Laced together, they make for a brief but fascinating glimpse of planetary bodies in motion.

Two of the still images showing Earth and moon before and during Wednesday morning’s total eclipse. Credit: NASA

The animation was constructed from 31 images taken two minutes apart from 5:18 to 6:18 a.m. EDT. The images start just before the Moon entered the umbra, the darkest part of the Earth’s shadow.

“From Mercury, the Earth and Moon normally appear as if they were two very bright stars,” noted Hari Nair, a planetary scientist at the Johns Hopkins University Applied Physics Laboratory, in Laurel, Md. “During a lunar eclipse, the Moon seems to disappear during its passage through the Earth’s shadow, as shown in the movie.”

MESSENGER photographed Earth and moon on May 6, 2010 from 114 million miles (183 million km) away. Credit: NASA

Because the moon is so much darker than Earth its brightness has been increased 25 times to show its disappearance more clearly. I’ve included another picture of the Earth and moon against the starry backdrop of deep space also photographed by MESSENGER. Sure puts things in perspective. While not as breathtaking as photos of Earth taken by the Apollo astronauts, seeing our tiny home floating in the void effectively communicates how improbable our existence is. Thank goodness life got a grip and kept it. After 3.5 billion years of evolution the double helix has proven itself a force with which to be reckoned.

The 133-mile-wide double ringed crater Vivaldi captured at sunrise. The low sun highlights valleys and chains of secondary impact craters radiating away from it. Credit: NASA

MESSENGER has been in orbit around Mercury since March 2011 studying the chemical composition of the surface, measuring planet’s magnetic field, mapping polar ices and of course taking pictures. Enjoy a few recent ones.

Hollows on the floor of an unnamed crater on Mercury. Hollows may be areas “eaten away” by the ceaseless bombardment of particles in the solar wind. Or they may form when heat from volcanic activity melts away softer rocks. No one knows for sure. Credit: NASA

Moon and illusion in the Hyades tonight

The waning gibbous moon moves across the Hyades star cluster tonight October 11. This map shows the view through binoculars around 10 p.m. CDT. Moon is to scale. Source: Stellarium

Now that the eclipse is behind us, the moon has trotted off to the east out of the limelight.

It’s in that lengthly phase called waning gibbous, a period of 6+ days between full moon and last quarter. Can I coax you out for another look?

Tonight the moon will cross the Hyades star cluster that forms the V-shaped face of Taurus the Bull. Merely having the moon in Taurus hints at how close we are to the start of winter. Two months hence, the Bull, along with Orion the Hunter, will dominate the southern sky at 10 o’clock.

Taurus the Bull from the 19th century star atlas Urania’s Mirror.

But tonight around 10, Taurus makes its appearance in the eastern sky. Because the moon is still fat and bright you’ll better appreciate its passage through the Hyades with binoculars. By happy circumstance, the entire cluster neatly fits into the field of view of most pairs.

Orange-red Aldebaran is Taurus’ brightest star and completes the cluster’s V with a flourish. Don’t be deceived. This star is an impostor that by chance lies in the same line of sight as the star cluster. The Hyades form a gravitationally bound group of stars 153 light years distant and were born from the same cloud of gas and dust 625 million years ago. Aldebaran? Only 65 light years away and as solitary as our sun.

The moon moves its own diameter every hour as it orbits the Earth. You can see that motion overnight tonight as the moon approaches and then conjuncts with Aldebaran tomorrow morning. The map shows the view from northern Minnesota / Wisconsin. Source: Stellarium

Over the course of the night, the moon will slowly work its way across the Bull’s face, occulting or covering a number of fainter cluster stars along the way. One such star is 63 Tauri shining at magnitude +5.6. A small telescope 4-inches or larger will show the moon creep up to the star and suddenly blank it from view around 10:10 p.m. Central Daylight Time. Depending on your location, the moon’s path across the Hyades will shift a little north or south, and you may see different stars occulted.

Aldebaran-Sun comparison. Aldebaran is an orange giant star 44 times the sun’s size. The sun will also puff out like Aldebaran several billion years in the future when it starts burning helium in its core as Aldebaran is today. Credit: Wikipedia

By 5 a.m. CDT tomorrow morning Oct. 12 the moon will be in conjunction with Aldebaran about 1º to its north. Here we see yet another of nature’s illusions. The moon not only outshines Aldebaran by 26,000 times, it’s huge in comparison. But make no mistake, Aldebaran’s the giant here. Next to it, the sun looks puny and faint.

With a diameter 44 times solar, Aldebaran’s searing orange photosphere would reach all the way to the planet Mercury if put in place of the sun and overall shine 500 times as bright.

Another noteworthy star to look for in your binoculars is the pair called Theta 1,2 Tauri. Both belong to the Hyades although small uncertainties in their distances make it unclear if they’re a physical double star or like Aldebaran, a chance alignment. Once the moon’s out of the way, this is a fun star to try and split with your naked eye. Like two tiny pearls in a starry brooch, they make for a pleasing sight.

Awestruck in the valley of the comet

As jets spray dust and icy vapors in the distance, tall cliffs rise up on either side of the boulder-strewn valley which forms part of the neck of comet 67P/C-G. I combined two separate Rosetta photos to provide a more panoramic view. The picture spans 0.9 miles (1.5 km). Credit: ESA/Rosetta/NAVCAM

Suit up! We’re going for a hike across one of the starkest and most beautiful valleys in the solar system. The Rosetta spacecraft took this photo of the neck region of Comet Churyumov-Gerasimenko on October 2 from a distance of only 11.8 miles (19 km). I can’t help but see it as an invitation to explore.

Imagine crunching through dust and pebbles as you pick your way along the boulder field. When you finally stop to rest and look up, craggy cliffs tower against a sky black as crows wings and crazy with stars. Then you notice the sparkles. They’re subtle like ice crystals catching sunlight on a bitter cold morning. And it dawns on you you’re seeing comet dust dancing in the sunlight as it slowly settles to the powdery ground beneath your feet.

Boulder Cheops, taken by Rosetta’s OSIRIS narrow-angle camera on September 19, 2014, from a distance of 17.7 miles (28.5 km). The boulder’s about 148 feet (45 m) across. Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

Along another part of the comet’s neck, Rosetta’s narrow angle OSIRIS camera photographed the largest boulder – named Cheops – in a different rocky landscape. It reminded the Rosetta scientists of the famous pyramids at Giza, the largest of which was built as the tomb for the Pharoah Cheops. Spanning a little more than three school buses in length, the boulder rests on a rocky,dusty plain. Look closely and you’ll see what appears to be the same darker dust / rock fragments filling cracks in the bright boulder’s surface.

Wider context showing the boulder field with Cheops just below center. Credit: ESA/Rosetta/NAVCAM

Boulders on the moon and other cratered asteroids, planets and moons are easy to explain as impact ejecta from meteorites and small asteroid impacts. But the origin of comet rocks isn’t so straightforward. Were they formed as exposed pieces of the comet’s crust as ices vaporized and the surface deflated or even collapsed? Or might they have tumbled down from the cliffs above?

Hopefully we’ll get an answer to their origin as the mission continues. This past week Rosetta has been orbiting 12.4 miles (20 km) from the comet, but the decision has now been made to dip down to just 6.2 miles (10 km) next Wednesday October 15. At that altitude, the spacecraft will orbit 67P/C-G about every 66 hours. It’ll also get an even sharper view of the Philae’s landing site in preparation for the November 11th touchdown.

MOM sees Mars in 3D

This 3D picture was made from multiple images by India’s Mars Orbiter on September 28, 2014. To see it in 3D, don a pair of red-blue glasses or follow the instructions below to make a pair of your own. Credit: ISRO

Not long after India’s Mars Orbiter Mission (MOM) successfully put itself in orbit about the Red Planet in late September, the spacecraft took this 3D image and tweeted:

Use this template to make a pair of 3D glasses for viewing the Mars photo and any other 3D image that use the red-blue combo to see in 3D. Click for larger version.

“What sorcery is this? Get your 3D glasses to look at Mars the way I do.” The photo is a combination of images taken on September 28 from an altitude of about 46,300 miles (74,500 km). If you don’t have 3D glasses, MOM provided instructions on making your own by using the cutout provided along with a couple pieces of cellophane and red and blue markers. Very innovative. If any of you make a pair, let us know how well it works.

The dark, comma-shaped feature below the center of the disk will be familiar to many telescopic observers of the planet. It’s comprised of the heavily-cratered highland region called Sinus Sabaeus and the flat, rock-free plain Sinus Meridiani (fat end). NASA’s Opportunity Rover landed in Sinus Meridiani (a.k.a. Meridiani Planum) on January 25, 2004 and still takes pictures and measurements to this day.

Regular 2D Mars showing the large dust storm in the planet’s northern hemisphere this fall. The southern ice cap is just visible along the bottom edge of the planet. Credit: ISRO

Both 2D and 3D photos show a significant dust storm blasting across Mars’ northern hemisphere and a pink-tinted southern polar ice cap. The color might come from dust in the atmosphere or rained out on the cap itself.

Another photo of Mars released on October 7 shows Mars from an altitude of 41,350 miles (66,543 km) and features the Elysian region rich in ancient volcanoes. Credit: ISRO
Dark region towards south of the cloud formation is Elysium – the second largest volcanic province on Mars. Credit: ISRO

MOM transmitted a more recent photo on October 7 taken of a different hemisphere of Mars showing the Elysium region known for its many ancient volcanoes. To help you appreciate how many volcanoes dot the area I’ve included a separate, color-coded image taken by NASA’s Mars Reconnaissance Orbiter.

Mars’ volcanoes – seen in white and brown tones here – range in age from more than 3.7 billion years to as young as 500 million. It may still be active today. This color-coded map shows the Elysium region and the location of the first spacecraft from Earth to successfully land on the Red Planet – NASA’s Viking 1 mission which touched down July 20, 1976. Credit: NASA

Total lunar eclipse – what a beauty!

The moon just coming out of eclipse over Spring Lake north of Duluth, Minn. this morning October 8. Details: 200mm telephoto, ISO 800, 1 second exposure. Credit: Bob King

I hope your sky was clear for the total lunar eclipse. It sure wasn’t here. A big bank of clouds moved in before totality. I was shocked when I looked at the window to see a clear sky in the east and not a single star – or moon – in the west. That’s why man invented the car.

Moon around mid-totality with the planet Uranus (left) for company. Credit: Bob King

25 miles north of town the burnt orange moon slid out from under the clouds. It was already mid-eclipse, but no matter. I pulled over to the side of the road to enjoy the sight as twilight crept up from behind.

In binoculars Uranus was plain to see near the lower edge of the moon where the color was deep, rich and red. Up along the lunar topside the color graded to a pale straw yellow.

The full moon departs Earth’s shadow over a spruce bog tinged with fall color north of Duluth Wednesday morning around 7 a.m. Credit: Bob King

Clouds threatened again sending me fleeing to a lake shore and finally another roadside. Around 6:30 a.m. traffic picked up. Everyone driving south or west on their way to work and school got the astronomical treat of their life – the moon emerging from total eclipse right out the front windshield. Sweet!

The partially eclipsed moon glows against Earth’s setting shadow (the purple band) this morning. Full moons are directly opposite the sun, setting around sunrise and rising at sunset. When you look at the moon during eclipse you’re staring directly down the shadow cone cast by the planet. Credit: Bob King

For a total lunar eclipse to happen, the moon must be full and lie in the same plane as Earth’s orbit. Since the moon’s orbit is tilted 5°, it normally misses Earth’s shadow at full, passing a few degrees above or below it.

The moon partially covered in Earth’s shadow seen from Dayton, Ohio this morning. At the moon’s distance, the planet’s shadow is surprisingly small – only big enough to cover the Seven Sisters (Pleiades) star cluster. Credit: John Chumack

The full moon orbits behind the Earth opposite the sun; as the sun rises the moon sets. At the moon’s distance of 240,000 miles, the Earth’s shadow, both penumbra and umbra, spans a little more than 2° or about the size of the Pleiades star cluster.

Seems pretty small, doesn’t it?

But viewed from the ground, Earth’s shadow reaches from one end of the western horizon to the other. In the evening, the shadow is equally broad but appears in the eastern sky. This morning we had the unique opportunity to see the partially eclipsed moon in Earth’s distant shadow at the same time as seeing the much bigger near-shadow of the planet. Wild thought.

Full sequence of this morning’s total lunar eclipse. Details: Canon 6D camera, 80mm refractor, 2-second exposure at ISO 6400. Credit: John Chumack

Lunar eclipse photo tips, times, live streams

On Wednesday morning October 8, Earth’s shadow will nibble away at the moon during the wee hours eclipsing it for the second time this year. Credit: Bob King

Ready for Wednesday’s morning lunar eclipse? Some people – and I envy them at times – treat an eclipse more casually. They enjoy the show with no desire to set up a telescope or take a photo. For those of us can’t part with our cameras, here’s a little guide to help you get better pictures.

As a photographer, I’m compelled to shoot at least a few photos of an event as rare as a total eclipse. Someday I’ll let it all go and just kick back in a lawn chair as the shutters clack around me. But until then the camera will be at my side.

From Philadelphia and other eastern U.S. cities the partial phases of the eclipse will take place with the moon well up in the western sky. By the start of totality, the moon will have dropped to within about 6º of the horizon as shown here. Source: Stellarium

If you’re also into photography and would like to grab a few shots, here are a few tips on what equipment you’ll need and camera settings. This eclipse offers unique opportunities especially for the eastern half of the country because the eclipsed moon will be low in the western sky near the start of and during morning twilight.

In the Midwest at the start of the hour-long totality, the red moon will be about 20º (two fists) above the western horizon. From the East Coast the moon slips into total eclipse only a half hour before sunrise 6-7º high. So if you live in the eastern half of the country, find a site with a good view to the west.

Seen from Denver, total eclipse begins with the moon 30º high (three fists). All of totality and all partial phases of the eclipse will be visible from western Midwest west to Hawaii and Alaska. Source: Stellarium

A low moon means easier framing with a pleasing foreground like a grove of fall trees, a church or distant line of mountain peaks. And the lower it drops, the longer the telephoto lens you can use to enlarge the moon relative to the foreground. When the moon is high in the sky it’s more difficult to find a suitable foreground.

Sometimes it’s nice to have a foreground object to add character to your eclipse photos. Last April’s totally eclipsed moon joins the old Central High School clock tower in downtown Duluth, Minn. Mars at upper right. Details: 80mm lens, f/5, 1.6-second exposure at ISO 400 on a tripod. Credit: Bob King

As the scene brightens during twilight, balancing the light of the moon, your photos will get even more interesting. Textures and details in foreground objects will stand out instead of appearing as silhouettes.

Use the table below to plan when to watch depending on your time zone. The blanks mean the moon will have set by the time of the event.

Eclipse Events                         EDT                 CDT                MDT                 PDT

Penumbra first visible 4:45 a.m. 3:45 a.m. 2:45 a.m. 1:45 a.m.
Partial eclipse begins 5:15 a.m. 4:15 a.m. 3:15 a.m. 2:15 a.m.
Total eclipse begins 6:25 a.m. 5:25 a.m. 4:25 a.m. 3:25 a.m.
Mid-eclipse 6:55 a.m. 5:55 a.m. 4:55 a.m. 3:55 a.m.
Total eclipse ends 7:24 a.m. 6:24 a.m. 5:24 a.m. 4:24 a.m.
Partial eclipse ends ——— 7:34 a.m. 6:34 a.m. 5:34 a.m.
Penumbra last visible ——— ——— 7:05 a.m. 6:05 a.m.

Exposures and lens settings

Partial phase during the April 14-15 eclipse this year. Details: Telescope (=1300mm telephoto lens) at f/11, 1/250 second at ISO 400. Credit: Bob King

The full moon and even the partially eclipsed moon (up to about half) are so bright you can shot a handheld photo without resorting to a tripod. Exposures at ISO 400 are in the neighborhood of f/8 at 1/250-1/500 second. Only thing is, all you’ll get is the moon surrounded by blackness. These exposures are so brief almost nothing will show in your foreground except for possibly moonlit clouds. That’s usually fine for the early partial phases.

To capture the encroaching shadow during partial phases you’ll need to overexpose the sunlit part of the moon. Details: f/11, 2-second exposure at ISO 400. Credit: Bob King

Once the moon is more than half smothered in shadow, open up the lens to a wider setting – f/2.8 to f/4 – or increase the exposure.

Let the back of the camera be your guide. If the images look too bright, dial back. If too dim, increase exposure or open the lens to a wider aperture.

While you can continue to shoot the partially eclipsed moon at f/8 from 1/30-1/125 second, you’ll miss the best part – the portion filling up with Earth’s red shadow. To capture that, break out the tripod, open your lens all the way up – f/2.8-f/4 – and expose at ISO 400 between 1/4 and 1 second. You can also shoot at ISO 800 and cut those times in half, important if you’re using a longish telephoto lens. Remember, Earth’s rotation means the moon’s on the move and will show trailing if you expose longer than a few seconds.

Wide scene from April’s total eclipse with Spica below the moon and Mars to the right. Details: 24mm lens at f/2.8, 8-second exposure at ISO 800. The moon was deliberately overexposed to show it in a field of stars. You can vary the exposure to your taste but the shorter it is,  the fewer stars. Longer exposures will show trailing. Credit: Bob King

During totality, expose anywhere from 1/2-5 seconds at f/2.8-4.5 at ISO 400. Let’s assume you want to include both a foreground and stars in the picture using a standard or wide angle lens. Dial up to ISO 800 with you lens wide open and exposure of 6-10 seconds. On the 6-second end you’ll catch only the brightest stars but the moon won’t show trailing; on the longer end you’ll get lots more stars with some overexposure of the eclipsed moon.

The partial lunar eclipse of June 4, 2012, pre-dawn at moonset, from home in southern Alberta. This is a single exposure with the Canon 60Da and 18-200mm Sigma lens at 115mm and at f/5.6 for 0.4 sec at ISO 160. Copyright: Alan Dyer

Where parts of the eclipse happen in twilight, even mobile phones may suffice. There should be enough light to capture a pretty scene with the moon just emerging from total eclipse and during the ensuing partial phases.

If you’re clouded out or on the wrong side of the planet for the eclipse, you can catch live webcasts from the following sites:

* Gianluca Masi’s Virtual Telescope
* Griffith Observatory in Los Angeles

Clear skies!

Poor Uranus – we won’t forget you, I promise

Uranus and Earth compared. Uranus has an atmosphere of hydrogen and helium with clouds of ammonia and methane. It’s the methane that gives the planet its characteristic aqua color. Although little more than a dot in the sky, the planet’s 4 times larger than Earth. Credit: NASA

Poor Uranus. So dim it barely gets noticed. A lost soul. But every year at opposition, it’s nice to give the 7th planet its due. Uranus will be closest to the Earth on Tuesday October 7 at “just” 1.8 billion miles (2.9 billion km) or 19 times the Earth’s distance from the sun.

Understandably, the naked eye planets get most of our attention. They’re brighter, closer and bigger. We can follow them without optical aid, and when viewed through a telescope, there’s usually cool stuff to see. Mars wows with polar caps and dust storms, Jupiter shows his stripes, Venus and Mercury’s phases look like miniature versions of the moon and Saturn spins a hula-hoop.

Shoot a line from Beta Pegasi (upper right) through Gamma Pegasi and continue about one fist to the lower left to Delta Piscium. Uranus is 3 degrees south-southeast of Delta to the left of a similarly bright star. Use the binocular map below for further help. Click map for a larger version. Source: Chris Mariott’s SkyMap

Uranus at magnitude +5.7 can be seen with the naked eye just like the others if you know exactly where to look. This season it tracks slowly across the middle of Pisces the Fish below the bright fall asterism, the Square of Pegasus. Finding and following this tiny blue orb will be easier than usual thanks to a lucky alignment.

Here’s the scene in a pair of 7×35 or 7×50 binoculars. The numbers next to stars are magnitudes. Uranus, at magnitude 5.7, will slowly glide south of a similarly bright star now through December, giving skywatchers lots of time to spot and track the planet. Source: Chris Marriott’s SkyMap

Draw a line from Beta Pegasi, the upper right star in the Square, diagonally to Gamma Pegasi and continue in that direction until you bump into Delta Piscium. Uranus lies about 3º to its south in the same binocular field of view. To pinpoint the planet, use the binocular map. Right now, the planet lies about a degree to the east of a 5.7 magnitude star, its twin in brightness. Using this star as a reference, you’ll easily see Uranus’ slow westward crawl over the next three months.

With a diameter of 31,518 miles (50,724 km) Uranus is the third largest planet in the solar system after Jupiter and Saturn. Being so far away it takes 84 years to revolve once around the sun, 4 years longer than the average life expectancy of a U.S. citizen. One of my goals in life is to celebrate one complete Uranian year. Maybe even a little more.

Uranus has 27 moons in all. These are its five largest which range from 980 miles (Titania) to 293 miles (Miranda) in diameter. They’re composed of roughly half water ice and half rock. Credit: NASA

Uranus has 27 moons named after characters from the works of William Shakespeare and Alexander Pope and 13 known rings, the first of which was discovered only in 1977. NASA’s Voyager 2 spacecraft visited the planet in January 1986 and discovered 10 new moons and two new rings. A day on Uranus lasts just 17 hours 14 minutes. But the planet’s oddest trait is that it rotates on its side.

Only after 84 years would a hypothetical Uranian citizen be able to celebrate their 1st birthday. Uranus rotates on its side unlike the other planets with each of its four seasons lasting 21 years. It will be fall in the planet’s northern hemisphere until the 2028 winter solstice. Credit: Nature of the Universe with additions by Bob King

All the other planets have tilted axes but they rotate right side-up generally perpendicular to the plane of the solar system. Not wayward Uranus. With an axis tilted at 98º, it rotates on its side like a bowling ball! This makes for curious seasons. Since Uranus takes 84 years to orbit the sun, each of the planet’s poles gets 42 years of continuous sunlight during the summer season followed by 42 years of winter darkness.

The sun seen from the equator of one of Uranus’ moons during the northern “summer years”. It would circle the north celestial pole every 17-plus hours. Credit: Kurdistan Planetarium

Seen from Uranus (its cloudtops at least – below that it’s permanently overcast), as northern spring progresses toward summer, you’d see the sun the move in ever tighter circles toward the planet’s north celestial pole. On the solstice, the sun would be just 8º from the celestial pole and circle it once every Uranian day (17-plus hours). Then the sun would spiral out from the pole over the next 21 years until it finally set, not to return to view for another 42 years. Bizarre.

Astronomers think that long ago Uranus was struck by an Earth-sized planet at an angle that effectively tipped it over on its side like a well-placed football tackle.

Any telescope magnifying 100x or higher will show the planet as a tiny pale blue disk. Because Uranus’ atmosphere is almost featureless, higher powers and larger telescopes reveal little more on the planet. Not so the moons. Four or five are visible in 10-inch and larger scopes with Titania and Oberon the easiest. Were it not for the glare of the planet, an 8-inch would suffice. If you’d like to give the moons a try, Sky and Telescope has a very nice Javascript utility Moons of Uranus to pinpoint them at any time.

Uranus will be a snap to see in binoculars just east of the totally eclipsed moon for much of the central U.S. Wednesday morning October 8. It will be even closer (just below the moon) for observers in the western states. This simulated binocular shows the pair around 5:30 a.m. CDT. Source: Stellarium

The best time to view Uranus is without a bright moon nearby. Since the moon is now near full, you’ll want to wait a few nights to make your first observation. But Wednesday morning’s total eclipse offers an exceptional opportunity.

Because the moon’s light will be quenched during total eclipse, you’ll be able to spot Uranus with ease in binoculars about a degree to the left or east of the moon.

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.


Rosetta’s comet grows feathers – see it in 3D

Jets of gas and dust are seen escaping comet 67P/C-G on September 26 in this four-image mosaic. Click to enlarge. Credit: ESA/Rosetta/NAVCAM

She’s gonna blow! These four separate images window-paned together were taken on September 26 by Rosetta as it orbited Comet 67P/Churyumov-Gerasimenko from a distance of 16 miles (26 km). They show jets of water vapor and dust erupting from several discrete locations beneath the surface along the neck region of the comet’s nucleus.

If you liked the first photo, you’ll go ga-ga for this 3D version created by Mattias Malmer. Grab your red-blue plastic glasses and place the red filter over the left eye and blue over the right. Malmer created the view by draping a navigation camera image over a 3D model of the comet and then photographing it from two slightly different perspectives. Click for large version. Credit: ESA/Rosetta/NAVCAM/processing by Mattias Malmer

The sun warms the comet’s coal-black surface, causing ices beneath to sublimate or change directly from solid to gas without becoming liquid. This is possible because of the near-zero atmospheric pressure at the comet. Pressure builds in the pockets of gas until they find escape through cracks or pores as plume-like jets. Comet dust born along with the gas fashions the coma and tail over time. Something similar happens when you shake up a bottle of champagne and then loosen the cork. Trapped carbon dioxide (what makes the “fizz”) blasts the cork across the room.

Comet Churyumov-Gerasimenko turning into the light. Don’t forget to hit the ‘full screen’ button at lower right. (Mattias Malmer) 

If you liked the still images, get ready for even more thrilling views created by 3D technical director Mattias Malmer. He used the same draping technique and then animated the stills. Be sure to check out his blog when you get a chance.

Comet Churyumov-Gerasimenko rotating in 3D (Mattias Malmer)

Heads up! (Mattias Malmer)

And now for the grand finale – what majesty!

3D rotation of Comet 67P/C-G with jets (Mattias Malmer)

Anticipating Wednesday’s awesome lunar eclipse

Watch for a ruddy moon in Pisces the Fish during the total lunar eclipse which happens Wednesday morning October 8th. The moon’s color can range from dark brown to coppery red depending on the transparency of the Earth’s atmosphere as described below. This map shows the view at the start of total eclipse as seen from the Midwest. Source: Stellarium

If you missed last April’s total lunar eclipse because of weather or commitments, you’ve got a second chance Wednesday morning October 8th. This is the final total lunar eclipse of 2014 and the second of four in a series called a tetrad – four consecutive total eclipses occurring at approximately six month intervals this year and next.

On Wednesday morning October 8, the moon will slide into Earth’s shadow and we’ll be treated to a total lunar eclipse. The outer shadow or penumbra only lightly shades the moon; for most of us the eclipse begins when the moon touches the inner, darker shadow called the umbra. Times are shown for each stage of the eclipse. Add one hour for EDT, subtract one hour for MDT and two hours for PDT. Credit: NASA / F. Espenak with additions by Bob King

“The most unique thing about the 2014-2015 tetrad is that all of them are visible for all or parts of the USA,” says longtime NASA eclipse expert Fred Espenak.

This eclipse happens during the early morning hours, so North American skywatchers will need to remember to set their alarm clocks. In the Midwest, partial eclipse begins at 4:15 a.m., when the moon’s eastern limb eases into Earth’s umbral shadow.

World map showing where the eclipse will be visible. Most of North America and much of Asia and Australia will see the event. Those living in the western half of the U.S. will see the eclipse from beginning to end. Farther east, the partially eclipsed moon sets at sunrise. Credit: NASA / F. Espenak

Earth’s shadow is composed of two nested components – the inner umbra, where the Earth completely blocks the sun from view, and an outer penumbra, where the planet only partially blocks the sun. Because the penumbra is a mix of shadow and sunlight, it’s nowhere near as dark as the umbra.

Animation showing the moon’s passage through the penumbra and umbra during the upcoming total eclipse. Credit: Tom Ruen

A lunar eclipse is divided into stages beginning with the moon’s entry into the penumbra. Most of us won’t notice any shading on the moon until it’s well inside the outer shadow about a half hour before partial eclipse begins. Look for a subtle darkening along its eastern edge.

During a lunar eclipse, the sun, Earth and moon are neatly lined up in space. For a few hours, the orbiting moon passes through Earth’s shadow and we experience a lunar eclipse. Credit: Starry Night

Because the Earth is a solid object, it casts a shadow in sunlight just like you and I. A lunar eclipse occurs when the sun, Earth and moon are precisely lined up in a row at the time of full moon, and the moon moves into Earth’s shadow.

Although the moon’s doing all the moving, it looks like the shadow is encroaching on the moon, slowly devouring it nibble by nibble. When the moon’s about half covered you’ll notice that the shadowed half is deep red or orange.

Artist view of Earth totally eclipsing the sun as viewed from the moon. Low angled sunlight filtered by our atmosphere is reddened in exactly the same way a setting sun is reddened. That red light bathes the moon’s surface which reflects a bit of it back toward Earth, giving us a red moon during totality.

Sunlight filtered and bent by Earth’s atmosphere spills into the umbral shadow and colors the moon a coppery red, burnt orange or rust. You can picture why this happens by pretending you’re standing on the moon looking back at Earth during total eclipse.

From your new perspective, the Earth passes in front of the sun, ringed by a glowing, red-orange atmosphere. Our atmosphere bends or refracts the light from all the sunrises and sunsets around the planet’s circumference into the umbra, adding color to the moon.

Depending on the amount of suspended particles called aerosols in Earth’s atmosphere at the time, the moon’s disk can glow a bright copper orange to deep brown-black. The more particles and haze, the greater the light absorption and darker the moon.

For the East Coast, totality begins during bright twilight with the moon low in the western sky. Skywatchers in the central U.S. will see all of totality and most of the final partial phases before moonset. If you live in the western U.S. you’ll get to watch the whole shebang in a dark sky.

Mid-eclipse is when the moon is deepest in Earth’s shadow. Since the top or northern end of the moon is closer to the shadow’s edge, it should appear noticeably lighter than the bottom half, which lies closer to the center.

The moon in mid-eclipse during the last total eclipse on April 14-15, 2014. You’ll notice a lot of variation of light and color across the disk. Credit: Bob King

After mid-eclipse, the moon slowly exits the Earth’s shadow and performs the whole show in reverse, transitioning back to partial eclipse and finally exiting the penumbra.

Besides the pleasure of seeing moon change color like a quickie version of fall, watch for the sky to darken as totality approaches. Eclipses begin with the sky flooded in bright moonlight nearly barren of stars. During totality, all the stars come back in a most breathtaking way. Be sure to sweep your gaze east to enjoy great views of the winter constellations including Orion.

A rare treat greets anyone with a pair of binoculars during next Wednesday morning’s total eclipse. The planet Uranus will sit a little more than one moon diameter to its southeast during totality. This view shows the scene from the U.S. Upper Midwest at 5;30 a.m. Source: Stellarium

By good fortune, the eclipsed moon will lie only about 1/2° west of the planet Uranus which should be easy to spot in binoculars during the hour of totality. Speaking of which, binoculars are a great way to enjoy the eclipsed moon. Somehow they give it a more three-dimensional look. Colors are richer and you’ll see the lunar disk suspended among the stars, a rare sight.

For your latest forecast, click HERE. I’ll have more information for you early next week including links for watching the eclipse on the web and photo tips. Stay tuned!