Eclipse spectacle / Record-thin moon / Aurora redux?

A total solar eclipse is seen in Longyearbyen on Svalbard, Norway, March 20, 2015. REUTERS/Jon Olav Nesvold/NTB scanpix

A total solar eclipse is seen in Longyearbyen on Svalbard, Norway, March 20, 2015.  The black circle is the moon covering the Sun. The “collar” around the moon is the Sun’s atmosphere called the corona, which is invisible to the eye except during an eclipse. Credit: Reuters/Jon Olav Nesvold/NTB scanpix

I’m told weather was great at Svalbard in Norway for this morning’s total solar eclipse. Completely clear skies. The solar corona, only seen during an eclipse, looks fashionably punk with a head full of beautiful, magnetically-aligned spikes.

A girl uses a welding mask to view a partial solar eclipse from Bradgate Park in Newtown Linford, central England March 20, 2015. A solar eclipse swept across the Atlantic Ocean on Friday with the moon blocking out the sun for a few thousand sky gazers on remote islands with millions more in Europe, Africa and Asia getting a partial celestial show. Reuters / Darren Staples

A girl uses a welding mask to view a partial solar eclipse from Bradgate Park in Newtown Linford, England to watch the eclipse. Millions of skywatchers in Europe, Africa and Asia got to see the partial show. Credit: Reuters / Darren Staples

Because the corona is a million times fainter than the blazing surface of the Sun you can’t see it in the daytime. Only during a eclipse when the moon covers our star can we finally glimpse its hidden crown.

A student observes the partial eclipse cast onto white paper at the Astronomical Observatory in Bialystok, Poland March 20, 2015. Credit: Reuters / Agencja Gazeta

Clouds proved to be the ideal filter for photographing the partial solar eclipse from Trieste, Italy Friday morning. Details: 50mm lens, f/6, 1/100 second at ISO 100. Credit: Giorgio Rizzarelli

Clouds proved to be the ideal filter for photographing the partial solar eclipse from Trieste, Italy Friday morning. Details: 50mm lens, f/6, 1/100 second at ISO 100. Credit: Giorgio Rizzarelli

Every day, the orbiting Solar and Heliospheric Observatory uses a coronagraph to create and artificial eclipse as seen from space. It uses an opaque disk to block the brilliant solar surface called the photosphere, so astronomers can study the corona any time without the expense, time and uncertain weather that can make eclipses on Earth so touch-and-go.

A view from a plane during the so-called "Eclipse Flight" from the Russian city of Murmansk to observe the solar eclipse above the neutral waters of the Norwegian Sea, March 20, 2015. A partial eclipse was visible on Friday, the first day of northern spring, across parts of Africa, Europe and Asia. The total eclipse of the sun was only visable in the Faroe Islands and the Norwegian archipelago of Svalbard in the Arctic Ocean. REUTERS/Sergei Karpukhin

This is one way to guarantee a cloud-free view of a total eclipse. A view from a plane during an “Eclipse Flight” from the Russian city of Murmansk to observe the event high over the Norwegian Sea. Credit: Reuters / Sergei Karpukhin

While very dilute compared to the Sun itself, the corona is extremely hot, about a 1,800,000° F. During periods of high solar activity, especially during the peak of the 11-year sunspot cycle, the corona is evenly distributed around the solar disk. In “slow” times, it stretches out in long streamers from the Sun’s equator.

The corona’s shape is determined by magnetic fields that originate from within the Sun and extend outward for some 5 million miles. I’ve been fortunate enough to stand under the moon’s shadow during several eclipses, and it’s always the highlight. The Sun’s atmosphere, threaded with delicate loops and spikes, looks electric. Alive. If you’ve never seen a total solar eclipse, make sure to put it on your bucket list.

A very, very young lunar crescent might be viewable this evening just about 20 minutes after sunset nearly due west about 25 degrees (2.5 outstretched fists) below Venus. Source: Stellarium

A very, very young lunar crescent might be viewable this evening just about 20 minutes after sunset nearly due west about 25 degrees (2.5 outstretched fists) below Venus. Source: Stellarium

The moon, responsible for today’s spectacle, will put on a solo encore this evening when it will be just far enough from the Sun to glimpse shortly after sunset.

This truly is a “young” moon, just 14 hours old as seen from the East Coast, 15 from the Midwest, 16 from the mountain states and 17 from the West Coast.

Use the diagram to help you find it. The moon will be just 3° high 20 minutes after sunset. You’ll need a very open, clear sky and a pair of binoculars to attempt the challenge.

If you were out early this morning you might have seen a few rays of northern lights. Credit: Guy Sander

If you were out early this morning you might have seen a few rays of northern lights. Credit: Guy Sander

Ah, the aurora. Hard to believe, but it’s been glimmering in the north for four nights in a row as seen from the northern U.S. and southern Canada. Guy Sander of Duluth spotted it at 1:15 this morning and brought his camera along for the ride.

NOAA space weather forecasters are predicting a G1 or minor geomagnetic storm for this evening before activity tapers off for the weekend. Cause? Another one of those holes in the Sun’s corona that allows subatomic particles to flow as free as the spring breeze from there to here.

Speaking of spring, the vernal equinox begins this evening at 5:45 p.m. (CDT). That’s when the Sun crosses the celestial equator moving north. Day and night are an equal 12 hours apiece across the planet except for the North Pole where the Sun will be up 24 hours now through the first day of fall. The South Pole will see their last day of 24-hour sunlight; starting tomorrow 6 months of night commence.

New binocular nova discovered / Jupiter event tonight / Aurora update

Animation showing the star field before the nova appeared and after. It's currently bright enough to see from a dark sky site with the naked eye. Credit: Ernesto Guido and Nick Howes

Animation showing the star field before the nova appeared and after. It’s currently bright enough to see from a dark sky site with the naked eye. Credit: Ernesto Guido and Nick Howes

A star undergoing a massive thermonuclear explosion called a nova was discovered yesterday (March 15) in the constellation Sagittarius the Archer by Australian amateurJohn Seach. He found it in photos he took with a digital SLR camera and low-light 50mm lens.

It’s the second nova to whistle from the Teapot constellation this year. The first appeared in mid-February and became faintly visible in larger binoculars. Seach found nova #2 shining at magnitude +6, the naked eye limit. Other observers later confirmed the sighting at magnitude 5.3, dim but easily visible with the naked eye from a rural site, and 5.8.

This view shows the sky facing south-southeast just before the start of dawn in mid-March from the central U.S. The nova’s located squarely in the Teapot constellation. Source: Stellarium

This view shows the sky facing south-southeast around the start of dawn from the central U.S. at mid-month. The nova’s located almost in the center of of the Teapot constellation about 15° high. Source: Stellarium

Whether it brightens or begins to fade only time will tell, but any nova bright enough to see in binoculars is exciting news. I plan to be out looking at the next opportunity. I’ve included maps here you can use to point you to the “new star”.

Be aware that Sagittarius is rather low in the sky from mid-northern latitudes this time of year. To spot the nova you’ll need an open view toward the southeast. Start looking just before the start of dawn or about 1 hour 40 minutes before sunrise. Sagittarius is the next zodiac constellation to the east (left) of Scorpius.

Use this map along with a pair of binoculars to pinpoint the nova's location. Neighboring stars are numbered with their magnitudes (decimals omitted for clarity) to help you estimate the nova's brightness. Source: Stellarium

Use this map along with a pair of binoculars to pinpoint the nova’s location. Neighboring stars are numbered with their magnitudes (decimals omitted for clarity) to help you estimate the nova’s brightness. Source: Stellarium

Novae always occur in very close double stars, where one of the stars is a tiny but dense white dwarf and the other a more familiar sun-like star. The dwarf draws matter from the atmosphere of the normal star, which ultimately accumulates on its surface. There it’s heated to tens of thousands of degrees until igniting and burning explosively in a thermonuclear explosion.

Suddenly, a dim unnoticed star brightens 50,000-100,000 times in a matter of hours, luminous enough for someone back here on Earth to spot it in binoculars. Simply remarkable.

Material gets blasted into space at tremendous speeds – already astronomers have measured gas moving away from the nova at speeds of over 6.2 million mph (10 million kph)!

Jupiter's four brightness moons shown for tonight (March 16) around 9:50 p.m. CDT just before Ganymede eclipses Europa. Created with Stellarium

Jupiter’s four brightness moons shown for tonight (March 16) around 9:50 p.m. CDT just before Ganymede eclipses Europa. South is up like the view shown in many telescopes. Created with Stellarium

Things must heating up again in the sky. Not only do we have a bright nova but tonight Jupiter’s moon Ganymede eclipses Europa. The event will be one of the best of the Jupiter observing season and easily viewable in a small telescope.

The key to seeing an eclipse is for the moon to be covered in as much shadow as possible. The deeper a moon moves into another’s shadow, the fainter it gets and the more easily we can see its brightness plummet.  Tonight’s eclipse is the best remaining of the year for the Americas; when fully eclipsed by Ganymede, Europa’s light will fade by 2.4 magnitudes or 59%.

A weak display of aurora Saturday evening March 14. Credit: Bob King

Clouds finger a weak display of aurora Saturday evening March 14. Credit: Bob King

The eclipse is short! It begins at 9:51 p.m. (CDT) and ends at 9:55 p.m. just four minutes later. Set your scope up a half hour beforehand and let it cool down so your views will be sharp. Then about 5 minutes before eclipse start focus on Jupiter and get familiar with the uneclipsed appearance of Europa. Now just watch as Europa dims (in comparison to the other moons) and then re-brightens.

There was a lot of potential aurora in the forecast over the weekend, but skywatchers in the U.S. may have looked in vain for it.  But … we did see some. On Saturday evening around 10:30 p.m. a weak aurora raised its head low in the northern sky. Mike Sangster of Duluth, Minn. reported an hour later that a few bright rays appeared.

Guess what? Minor geomagnetic storms are back in the forecast for tomorrow night St. Patrick’s Day. Wouldn’t it be nice if the northern sky wore a little green for the occasion.

Watch Io snuff out Ganymede at Jupiter tonight

The moon kisses up to Aldebaran last night (Feb. 25) during evening twilight seen from Duluth, Minn. Credit: Clint Austin

The moon kisses up to Aldebaran last night (Feb. 25) during evening twilight seen from Duluth, Minn. Credit: Clint Austin

First, my apologies. I so wanted to alert you to the half moon’s pass of the bright star Aldebaran last night. But there were network problems with the blog, and I wasn’t able to post.

No doubt many of you noticed it all the same. A quick look up at the moon and you couldn’t help but see the star a little more than one lunar diameter to the southwest. The farther north you lived, the closer they drew together. In far northeastern Canada the moon occulted Aldebaran. Checking the moon several times overnight, it was amazing to see how quickly it departed Aldebaran, forced by its perpetual orbital motion to “go east, young moon, go east”.

Tonight our satellite moves a fist further east in Taurus the Bull and beams atop Orion the mighty hunter at nightfall. It’s 8 days past new phase and absolutely resplendent with craters. Sic your telescope on it and marvel at the ruggedness of all that ancient terrain bludgeoned by forgotten meteorites and asteroids.

The view through the telescope this evening just before Ganymede is eclipsed by Io's shadow. Created with Stellarium

The view through the telescope this evening just before Ganymede is eclipsed by Io’s shadow. The deepest part of the eclipse will occur around 9:35 p.m. Created with Stellarium

East of Orion you’ll find the blazingly bright planet Jupiter right along the border of Leo and Cancer. I’ve written before about this being a special season for Jupiter’s moons. Because Earth’s equator is aligned with Jupiter’s, and the brightest moons orbit above the planet’s equator, we can see them eclipse and occult one another in what astronomers call “mutual events”.

Tonight, little Io will cast its shadow on the largest Jovian moon, Ganymede. While not a total eclipse, it’s close, with a good deal of Ganymede in shadow at maximum (although not 97% as I wrote earlier). This should be easily visible in a small telescope at low to medium magnification. The eclipse begins at 9:31 p.m. CST (3:31 UT) and ends at 9:40 p.m. (3:40 UT). Jupiter will be very well placed for viewing across all of the Americas at the time.

Now here's something cool - a double mutual event. Europa eclipses then occults Io on January 28 captured by Theo Ramakers of Oxford, Georgia.

In this double mutual event, Europa eclipses then occults Io on January 28 captured by Theo Ramakers of Oxford, Georgia. The eclipse is quick in the time lapse, occurring about 1/2 second in. Look for the shadow passing across the top of Io.

Get that scope out at least a half hour beforehand and let it cool down if you’re in a cold climate otherwise Jupiter will look all mushy. Then start watching about five minutes before the eclipse begins, so you can get familiar with Ganymede’s normal brightness.

During the eclipse you won’t be able to see Io’s shadow with your eye, but Ganymede will fade by one magnitude and then re-brighten as the shadow first covers and then departs its 3,275-mile-wide globe.

Wishing you clear or at least partly cloudy skies tonight!

Jupiter doesn’t get any better than NOW

Jupiter shows off its north and south equatorial belts – the two thick stripes – and Great Red Spot in this picture taken on Feb. 6. Credit: Christopher Go

Brash Jupiter finally has its day. Big and bright, the planet’s been easing up in the east earlier and earlier each night this winter. I’ve been watching it through my car window while driving home from work at dusk.

Jupiter reached opposition yesterday, when it beamed directly opposite the Sun in the sky. Like the full moon, the planet rose at sunset and remained visible all night, setting at sunrise. Opposition occurs when Earth and Jupiter line up on the same side of the Sun putting them closer together than at any other time of the year.

Jupiter and Earth are lined up on the same side of the Sun at opposition and closest for the year. Now is the best time to observer the solar system’s largest planet in a telescope or pair of binoculars. Credit: Bob King

Skywatchers seize the time of opposition to regularly observe a planet; closeness equals greater brightness and also larger apparent size. And size is what we need to see the fascinating details that make these quivering disks come alive as real places.

This weekend, Jupiter’s chubby face will be 1.5 times larger than when viewed around solar conjunction on August 26th when the planet drops into the Sun’s glare in the western sky.

Jupiter straddles the border of Leo and Cancer not far from Leo’s brightest star Regulus. The inset shows how the planet and its four brightest moons will look in a small telescope this evening around 9 p.m. CST. North is at upper left in inset. Created with Stellarium

So what’s there to see? Lots! Jupiter is a meteorologist’s paradise, but you don’t have to be one to appreciate the planet’s changeable weather and balletic moons. Even binoculars will show a tiny disk, and if you look very closely, you’ll see up to four star-like points flanking either side of the planet. These are the four brightest moons – Io, Europa, Ganymede and Callisto in order of increasing distance from Jupiter.

Jupiter’s about 11 times larger than the Earth and has no solid surface. Its globe is covered in clouds of ammonia ice.

As they revolve about the planet, they create new arrangements every night. I’ve seen lots of eye-catching groupings with some of the most surprising symmetries over the years. And while I enjoy The Tonight Show, Jupiter’s moons are usually more entertaining. To find out where they are and what they’re up to any given night, check out Sky and Telescope’s Jupiter Moons Observing Tool.

Sometimes a moon will “disappear” when it passes in front of or behind the great planet. Other times, Jupiter’s shadow will eclipse a moon. This season, because Earth’s equator is aligned with Jupiter’s, we can even see the moons eclipse and occult one another in what astronomers call “mutual events”. For your observing pleasure, I’ve included a list of the best mutual events at the end of this article.

One of the most amazing discoveries I made some year back was that I could see Jupiter’s moons as actual disks, not just points. When the air is especially steady, power up to 150x or higher and look closely at each of the moons in a 6-inch or larger scope. In good seeing, each will show a minute disk with Ganymede clearly the largest of the four. One of them, Io, is colored orange from sulfur-laden lavas erupted from its interior that now coat the surface. Can you see the color?

With a small telescope and low magnification (40- 50x) two gray “tire tracks” rut the planet’s disk. These are the north and south equatorial belts, so called because they flank Jupiter’s equator. Higher power, steady air and a bit of stick-to-itiveness and you’ll also pick out the thinner stripes like the north and south temperate belts and the polar regions which look like gray beanie caps.

I’ve labeled the most prominent belts in this photo taken by Anthony Wesley on Feb. 6, 2015. Strong winds whip Jupiter’s clouds into alternating dark belts and bright zones. Sulfur and possibly phosphorus compounds may be responsible for the dark tone of the belts as well as the Great Red Spot. Credit: Anthony Wesley

Dark belts are separated by lighter zones and the whole works is streamed into stripes by narrow, high-speed winds called jets that border the zones and belts. Winds rip along at up to 400 mph (640 km/hr). Because Jupiter makes a complete spin on its axis at the amazing rate of just 9.9 hours, you can watch new features rotate into view by revisiting the planet in your telescope several times during the night.

Jupiter’s weather is as changeable as Earth’s. Belts narrow, widen, split in two or even disappear altogether for a couple years before reforming. The familiar Great Red Spot (GRS), a hurricane-like storm more than twice Earth’s diameter that’s raged for centuries, changes color from pale tan to brick red. This year it’s pink-colored and nestled in a pale “hollow”. You’ll need good seeing, a 4.5-inch or larger telescope and magnification of around 100x to spot it.

To know when to look for the GRS, click HERE and you’ll get dates and times when it’s front up and center on Jupiter. The times shown are Universal or Greenwich Time. Subtract 5 hours for Eastern, 6 for Central, 7 for Mountain and 8 for Pacific.

I can’t say enough about this planet. Mars shows lots of detail too, but it’s typically so small you have to work hard and consistently to appreciate its vague markings. Saturn of course is fantastic but features in its atmosphere are subtle and change slowly. Venus and Mercury show phases but precious little else. Only Jupiter happily gives away its secrets even to the beginning observer with a small telescope.

Now here’s something cool – a double mutual event. Europa eclipses then occults Io on January 28 captured by Theo Ramakers of Oxford, Georgia.

Below are times when the planet’s moons pass either fully or partially in front of one another (called an occultation) and eclipse each other.

During an occultation, you can watch the moons get closer and closer until they merge into a single object. Minutes later they separate and go their own way. To watch one, be sure to start observing at least 10 minutes before the times shown. Moons will fade in brightness when occulted but I’ve found this difficult in practice to see because they’re sitting atop one another and appear as one.

In an eclipse, the shadow of a moon will cause the other to fade for a few minutes and then re-brighten. If the fade is 50% or more, you can see the change in brightness through the scope. Really fun to watch. Bolded events are the best eclipses of the bunch.

Mutual events for Jupiter’s satellites in February – Times are CST:

Feb. 8 11:26-29 p.m. Io occults Europa (pair very close to Jupiter)
Feb. 8 11:32-34 p.m. Io eclipses Europa 2% shadowed (pair very close to Jupiter)
Feb. 14  6:20-28 p.m. Europa eclipses Io 85% (comfortable separation from planet; should be very easy to see fading)
Feb. 16 1:23-26 a.m. Io occults Europa
Feb. 16 1:44-47 a.m. Io eclipses Europa
Feb. 17 11:48-57 p.m Europa eclipses Callisto 44%
Feb. 19 6:34-43 p.m. Io eclipses Ganymede 84% (deep eclipse, very nice!)
Feb. 21 8:04-11 p.m. Europa occults Io
Feb. 23 7:42-47 p.m. Ganymede occults Io
Feb. 23 8:38-45 p.m. Ganymede eclipses Io 57% (pair very close to Jupiter)
Feb. 26 8:17-24 p.m. Io occults Ganymede 36%
Feb. 26 9:31-40 p.m. Io eclipses Ganymede 97% (Deepest and best eclipse event of the month)
Feb. 26 10:27-39 p.m. Callisto eclipses Ganymede 58%
Feb. 27 11:33-36 p.m. Europa eclipses Ganymede .2%
Feb. 28 10:09-16 p.m. Europa occults Io 59%
Feb. 28 11:01-11:08 p.m. Europa eclipses Io 90% (another excellent eclipse)

Saturn, meet Super Saturn … and try not to be jealous

Artist’s conception of the extrasolar ring system circling the young giant planet or brown dwarf J1407b. The rings are shown eclipsing the young sun-like star J1407, as they would have appeared in early 2007. Credit: Ron Miller

Saturn, you’ve got company. A planet orbiting the young, sun-like star J1407 in the southern constellation Centaurus has a ring system that makes yours look, well, microscopic. Not only is the planet they encircle much more massive than either Jupiter or Saturn, but the rings are 200 times as wide and packed with material. Discovered in 2012, it’s the first system of its kind to be found in another solar system.

Eric Mamajek (University of Rochester) and Matthew Kenworthy (Leiden Observatory) co-authored a recent paper detailing their discovery. The system consists of 37 rings with a total diameter of 74.5 million miles (120 million km). That’s 438 times the size of Saturn’s primary rings. If you plucked out the Sun and put J1407b in its place, its ring system would reach more than three-quarters of the way to Earth.

Let’s look at it another way. Step outside one of these winter mornings for a peek at Saturn in Scorpius. To your eye it looks exactly like a star. 10x binoculars begin to reveal an oval shape that hints at the planet’s rings. If we could replace Saturn with J1407b, the exoplanet’s rings would span 35° of sky or twice the length of the constellation Orion the Hunter. Can you imagine that?

Saturn and its primary ring system (top). Bottom view shows the planet at scale surrounded by the tilted Phoebe Ring. Saturn’s primary rings span 170,000 miles. Credit: NASA

Let me temper our excitement a teeny bit by saying we’re not including Saturn’s Phoebe Ring, an extremely faint and tenuous ring discovered in 2009 by NASA’s Spitzer SpaceTelescope. Tilted 27° to the main ring plane with a diameter up to 7.4 million miles it broadens Saturn’s domain considerably, but there’s hardly anything there compared to the massiveness of J1407b’s lovely loops.

Each of J1407b’s rings extends up to several tens of millions of miles in diameter; the mass of the entire system comes to around 100 million times that of Earth’s moon. That’s a lot of stuff to make moons out of and exactly what the researchers believe is happening. They’ve got evidence of it, too.

There are gaps in the system carved out by possible “exomoons” coalescing from the material like a miniature version of our own solar system which evolved from a similar though much larger cloud of dust and gas 4.6 billion years ago. One gap, located 41 million miles (61 million km) from the massive planet at the hub, has been cleared by a satellite with an estimated mass 45 that of Earth.

One of the SuperWASP 8-camera setups. Each is equipped with a fast Canon 200mm f/1.8 telephoto lens. Credit: Warwick University and Keele University.

Mamajek and Kenworthy discovered the rings while analyzing data from the SuperWASP (Wide Angle Search for Planets) program. SuperWASP employs eight cameras at each of two robotic observatories that operate year-round and cover the entire sky, both northern and southern hemispheres. Millions of stars are photographed simultaneously with the hope of catching one in the act of being eclipsed by an orbiting planet. During an eclipse, the star fades and then returns to its original brightness as the planet blocks the light and moves on.

The researchers studied a 12th magnitude orange dwarf star with the swanky name of 1SWASP J140747.93-394542.6 (full name for J1407) which underwent a series of deep eclipses lasting 56 days back in April-May 2007.

Simulation of the eclipse of the star J1407 by the ring system around its putative exoplanet J1407b. Each time a ring passed in front of the star, it dimmed. When entering a gap, the star brightened up again. Graphing the highs and lows, scientists created a profile of the ring system. See video below. Credits: Eric Mamajek, Matthew Kenworthy

“The eclipse lasted for several weeks, but you see rapid changes on time scales of tens of minutes as a result of fine structures in the rings,” said Kenworthy. Each ring caused a dip in the star’s light up to 95% implying that the rings are thick and massive. Lots of material there likely means lots of future moons.

Though J1407b is much too far away to observe the rings directly, they made a detailed model of the ring system based on the rapid brightness variations in the star light passing through it. The object at the center of this celestial pinwheel is almost certainly a planet but has yet to be seen. No surprise, as it’s so much smaller than the rings which surround it.

Besides finding another Saturn, a wonderful discovery in itself, we can now watch as a disk of dust around another planet gets its rings carved by exomoons. Sometimes the universe is simply … unbelievable.

Once-in-6-year-alignment makes Jupiter’s moons dance in shadows

Jupiter and his Great Red Spot photographed on January 3rd through a 14-inch telescope. Credit: Paul Maxson

Now that Jupiter’s up in the east by 9 o’clock local time, we have lots of opportunities to observe it before bedtime. That’s good because the Jupiter system is currently edge-on to the Earth and Sun, allowing us to see the planet’s brightest moons eclipse and occult one another now through August.

Io, Europa, Ganymede and Callisto all orbit very close to the plane of Jupiter’s equator. From our perspective on Earth, the moons usually pass a little above or below one another and escape each other’s shadows. But every six years or so, Earth and Sun cross the plane of the satellites’ orbits putting us “level” with Jupiter’s equator.

Instead of missing one another, the moons appear to merge into one during occultations and cast their shadows on one another during eclipses. This cyclic but relatively rare planetary alignment last happened in 2009 and won’t again until 2020.

The six varieties of eclipses and occultations possible among Jupiter’s four brightest moons now through August. Credit: Dave Dickinson

While you may not be able to resolve the four brightest moons in your telescope, you’ll have no difficulty watching them approach one another and meld into either an extremely close “double moon” or a single object during an occultation. Minutes later, the pair breaks apart as each moon follows its own track around the mothership.

Io eclipses Ganymede back on August 16, 2009. Credit: Christopher Go

During an eclipse, one moons will cast a shadow on another, causing it to fade the same way our moon dims when entering Earth’s shadow during a lunar eclipse. Assuming a fairly deep eclipse, you’ll be able to watch a Jovian moon fade and then re-brighten in a matter of minutes.

Again, you won’t see the shadow itself because the moons are so tiny, but the drop in brightness is clearly visible especially during deep eclipses.

With Jupiter coming to opposition on February 6th you’ll have lots of opportunities to catch at least one of each type of phenomenon. Not to mention, that all the moons cross over the Jupiter’s bright equatorial zone as they orbit the planet, making shadows they cast on the cloudtops easier than ever to see. Those are called shadow transits, and we’ll feature those soon, too.

Io eclipses Ganymede on Christmas night 2014. Credit: Paul Maxson

Below is a list of the best upcoming mutual events of the four brightest satellites for locations across North America. To view them, you’ll need at 3-inch or larger telescope.

A drop of 0.5 magnitude or larger during an eclipse or occultation should be apparent to the eye by carefully comparing before and after views. For occultations, you can also have the pleasure of seeing the moons in close embrace

Two for the price of one. Io occults and then eclipses Europa in this animation of still photographs taken on September 28, 2009. Credit: Brian Combs

For a customized table of events when Jupiter’s easily visible in a dark sky from your location, click over to this list of observatories, do a Control-F (Command-F on Mac) and type in the name of a larger city within a few hundred miles of your location. Next, copy the 3-digit code number and then paste it into the window on the IMCCE table creation page. Click enter and you’ll get a handy list of every event visible from your location through August.

To help you pick which eclipse events are worth your time, make sure the “Δm” (change in magnitude) is 0.5 or greater. Times listed in the table are Universal Time. Subtract 5 hours for EST, 6 for CDT, 7 for MST and 8 for PST. Also, each moon is listed by number rather than name. Io=1, Europa=2, Ganymede=3 and Callisto=4, so “2e4″ means Europa eclipses Callisto.

More event information and some great animations are available at SAF Planetary Observation Commission’s page.

Events – Times are CST:

Jan. 15 – Io eclipses Callisto starting 6:13 a.m., ending 6:39 a.m. Magnitude drop: 0.5
Jan. 18 – Ganymede occults Europa starting 8:31 p.m., ending 8:37 p.m. Mag. drop: 0.5
Jan. 23 – Callisto eclipses Ganymede starting 3:06 a.m., ending 3:20 a.m. Mag. drop 1.4!
Jan. 25 – Ganymede occults Europa starting 11:13 p.m., ending 11:19 p.m. Mag. drop 0.5
Jan. 28 – Europa eclipses Io starting starting 12:18 a.m., ending 12:27 a.m. Mag. drop 0.5
Jan. 29 – Io occults Europa starting  8:31 a.m., ending 8:35 a.m. Mag. drop 0.6

Nice sequence showing Io occulting Ganymede on December 21, 2014. The moons meet and part over 22 minutes. Credit: Paulo Casquinha

Bear in mind, these are the most easily observed events. There are many more! I’ll post a new list at the beginning of every month through the summer. Let us know if you get to see one of these. Good luck!

Biggest sunspot in 5 years may steal the show during today’s eclipse

Active region 2192 (AR 2192) is about the same size as the planet Jupiter or 87,000 miles end to end. This illustration is based on a photo of the  sunspot group taken October 22. Click for more information and animations. Credit: NASA/SDO/Alex Young

Wow, have you ever? Look at that sunspot group. If it seems bigger than any you’ve ever seen you’re right. At least in the last five years. Active region 2192 is the largest sunspot group recorded so far in Solar Cycle 24 which began in 2009. Solar cycles typically last about 11 years and chart the rise and decline of sunspots, flares and other solar activity.

The giant spot group 2192 faces Earth squarely today and should look spectacular during this afternoon’s partial solar eclipse.  Here we see many cooler, darker umbrae surrounded by the lighter penumbrae. The group has a magnetically complex beta-gamma-delta magnetic field ripe for flaring. Credit: NASA/SDO

Yesterday I grabbed my #14 welder’s glass and couldn’t believe how easy it was to see this behemoth. If you have a filter ready for today’s partial solar eclipse, use it to look at the sun anytime, and you’ll see what I mean.

Rarely do naked eye sunspots look like more than dark dots. Region 2192 stands apart. Look carefully through your filter and you’ll discern that the left side (eastern half) looks darker than the western side. That’s because most of the darker bits, called umbrae, are concentrated there.

The sun this morning Oct. 23 with our featured sunspot group facing toward Earth. Credit: NASA/SDO

Sunspots have two parts – a dark core (or cores) called an umbra surrounded by a pale, skirt-like penumbra. Each spot group marks a region on the sun’s fiery outer skin where magnetic energy is concentrated. The magnetic forces that permeate the Sun are the same as those that flow the magnets on your refrigerator but contain vastly more energy because they cover huge regions of the Sun’s surface or photosphere.

Strong magnetic fields within a sunspot group quell the turbulent churning of the photosphere, chilling the region by several thousand degrees. Sunspots appear dark against the Sun’s blazing disk because they’re cooler. If you could rip them away from the Sun and see them alone against the sky, they’d be glaringly bright.

The crazy big sunspot group unleashed an X-class flare around 9 a.m. October 22 seen in these photos taken in two “flavors” or far ultraviolet light by NASA’s Solar Dynamics Observatory. Credit: NASA/SDO

Twisty fields of magnetic energy looping above sunspots can become unstable in the hot, turbulent environment of the Sun’s surface, which bubbles and boils like overcooked oatmeal in a microwave oven, and release their pent-up power in violent explosions called solar flares.

2192 has been no stranger to flares. Harboring a complex beta-gamma-delta magnetic field where the magnetic “north poles” and “south poles” lie side by side, they practically beg to explosively reconnect. Since Monday, the spotted beast has spewed two X-class (most powerful) and 8 M-class (medium strength) flares. So far though, none has been directed toward the Earth.


Watch the big group rotate onto the sun’s face and grow in the 72-hour animation made with NASA’s Solar Dynamics Observatory

That’s likely to change very soon since the group is now squarely facing the planet. Already, NOAA’s space weather forecast calls for a 95% chance for more M-class and 55% chance for X-class flare in the next 24 hours. Space weather is expected to be strong during the same period. That might mean auroras coming around as soon as this evening. I’ll keep you posted.

Not only will the sun be eclipsed this afternoon but the planet Venus shines just 1.1 degrees to its north. Venus is very close to superior conjunction which occurs early Saturday. In the photo, the planet is in the background well behind the Sun. Don’t count on seeing Venus – too much glare! This photo was taken from space by NASA’s Solar and Heliospheric Observatory this afternoon using a coronagraph to block the Sun from view. Credit: NASA/ESA

Good luck with today’s eclipse. If you need more information including viewing times for your city, please see my earlier blog on the topic.

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. Remember to look at the projection of the sun on the inner wall of the box – not through the pinhole itself.

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!

 

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

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!