Jupiter and the half moon invite you to look up tonight

Look for the half moon to the lower right of Jupiter tonight. Source: Stellarium

Look for the half moon to the lower right of Jupiter tonight. This map shows the sky around 9 p.m. local time looking high in the southwest. Besides the moon and Jupiter, other bright stars in the scene are Regulus in Leo the Lion, Pollux and Castor in Gemini the Twins and Procyon in Canis Minor (Small Dog). Source: Stellarium

As if to advertise that astronomy is as easy as looking up, the first quarter moon will be near Jupiter high in the southern sky at nightfall this evening. Take a look outside at dusk and let the exquisitely-cut lunar half-pie point you to Jupiter.

Jupiter and the four Galilean moons (named after Galileo, who first discovered them) around 9:30 p.m. tonight April 25. Source: Meridian

Jupiter and the four Galilean moons (named after Galileo, who first discovered them) around 9:30 p.m. CDT tonight April 25. South is up and east to the right as seen in many small scopes. Source: Meridian

Have telescope? Even a small glass will show all four of Jupiter’s brightest moons lined up in a neat row to the east of the planet around 9-10 p.m. 10x binoculars should easily show the two moons farthest from Jupiter tonight, Ganymede and Europa, as long as you can hold them steady.

The moon this evening. Dark seas or maria were once enormous craters  blasted in the lunar crust by asteroid impacts. Later, they filled with lava bubbling up from below. Spectacular craters blanket the white, ancient crust of the moon called the lunar highlands. Source: Virtual Lunar Atlas

The moon this evening. Dark seas or maria were once enormous craters blasted in the lunar crust by asteroid impacts. Later, they filled with lava bubbling up from below to become flat plains. Spectacular craters blanket the white, ancient crust of the moon called the lunar highlands. Source: Virtual Lunar Atlas

Want more? Take that scope or binoculars and point them at the moon. First quarter phase brings hundreds of impact-sculpted craters into view especially in the southern half of the lunar disk. I’ve labeled the dark “seas” or “maria” (the Latin term) and three prominent craters. Use a magnification of 40x or higher for the best views.

Hope you had a great Astronomy Day. If you weren’t able to attend an event, consider the moon and Jupiter your own private show.

How to find Hydra, the largest constellation in the sky

Hydra the Water Snake unfurls across the southern sky during late March and April evenings. The long constellation begins just below the bright planet Jupiter and coils toward the southeast, crossing the entire summer sky. Source: Stellarium

Hydra the Water Snake unfurls across the southern sky during late March and April evenings. The long constellation begins just below the bright planet Jupiter and coils toward the southeast, crossing the entire southern sky. The map shows the sky facing south around 11 p.m. local time in late March. Source: Stellarium

Hydra the Water Snake is not only the largest of the 88 constellations, it’s also the longest and one of the most ancient. This slender winding pattern of stars is named after the nine-headed serpent Hercules fought as part of his twelve labors. For every head he severed from the serpent, two more grew in its place. Some of us have days like that.

Hydra's coils are beautifully illustrated in Urania's Mirror, a star atlas made in 1825.

Hydra’s coils are beautifully illustrated in Urania’s Mirror, a star atlas made in 1825. Also shown are Crater the Cup, Sextans the Sextant and Corvus the Crow. Noctua the Owl (far left) and Felis the Cat (right) are defunct constellations no longer recognized.

You can get started in your quest to tame this sky snake by finding a place with a wide open view to the south. To see the entire constellation, you’ll need to be out around 11 o’clock in late March or 9:30 p.m. in mid-April. Start with the brilliant planet Jupiter due south at that hour. Not quite a fist below the planet you’ll spy the compact arrangement of five stars that form the snake’s head. From there, it’s an easy drop down to Alphard, Hydra’s solitary bright star, shining pale orange at second magnitude.

Photo showing the serpent on the rise below Jupiter and the constellation Leo. Credit: Bob King

Photo showing Hydra on the rise below Jupiter and the constellation Leo earlier this month. Credit: Bob King

The name Alphard comes from the Arabic al-fard meaning “the solitary one”. Appropriate considering it’s the only relatively bright star in a rather empty region of the sky. Alphard’s a orange giant three times as massive as the Sun and located about 177 light years from Earth.

Hydra is an ancient Greek constellation well known to Plato, Archimedes and their cohorts, but its roots dig deeper in time, all the way back to Babylon. The Mul.Apin tablets, compendium of Babylonian astrology and astronomy written about 1000 B.C., includes a serpent-like constellation called “Mush” that resembles our current Hydra.

Many people don’t care for snakes and water snakes in particular, but Hydra’s home to several fine galaxies and star clusters that we’ll get acquainted with as the ground softens and the first flowers appear later this spring.

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.

Lucky Friday the 13th for auroras? / Ganymede auroras hint at hidden ocean

Close-up of the complex sunspot group behind the recent CMEs arriving at Earth yesterday and today. Credit: NASA

Close-up of the complex sunspot group behind the recent CMEs arriving at Earth yesterday and today. Italian amateur spotted it with the naked eye using a safe solar filter today. Credit: NASA

Before we look in on Jupiter’s moon Ganymede to see what we can learn from its auroras, I wanted to update you on what’s going on with our own greeny lights here on Earth. The anticipated minor storm arrived late – around 5 a.m. Central time today but didn’t dip deeply enough into the U.S. for a good show.

Don’t give up hope yet. Activity from all the coronal mass ejections kicked out by sunspot group 2297 this week combined with streams of high speed particles from recent solar coronal holes should make for more storming tonight.  NOAA space weather forecasters are calling for a G1 (minor) geomagnetic storm which usually means skywatchers in the northern U.S. should be alert for northern lights. Maybe our luck will change – I can’t think of a better day for it to happen.

Meanwhile, 422 million miles away, a cyclical shift in the position of auroral ribbons on Jupiter’s largest moon Ganymede hint at a hidden ocean buried under 95-miles (150 km) of icy crust.

In this artist’s concept, the moon Ganymede orbits the giant planet Jupiter. NASA’s Hubble Space Telescope observed aurorae on the moon generated by Ganymede’s magnetic fields. A saline ocean under the moon’s icy crust best explains shifting in the auroral belts measured by Hubble. Credit: NASA/ESA

In this artist’s concept, the moon Ganymede orbits the giant planet Jupiter. NASA’s Hubble Space Telescope observed auroras on the moon generated by Ganymede’s magnetic fields. A salty ocean under the moon’s icy crust best explains shifting in the auroral belts measured by Hubble. Credit: NASA/ESA

Ganymede is the largest moon in the solar system and the only moon with its own magnetic field. The magnetic field causes aurorae, which are ribbons of glowing, hot electrified gas, in regions circling the north and south poles of the moon. Because Ganymede is close to Jupiter, it’s also embedded in Jupiter’s magnetic field. When Jupiter’s magnetic field changes, the auroras on Ganymede also change by “rocking” back and forth.

To generate a magnetic field a planet or moon must have material moving beneath its crust that’s able to conduct an electric current. On Earth that’s iron in our planet’s liquid outer core, on Ganymede it appears to be a salty subterranean ocean.

To see and photograph auroras you need an atmosphere. Incoming solar or Jovian energetic particles strike the air, excite the atoms and cause them to release light in response – this is what we see as the aurora.  Ganymede possesses a very thin atmosphere of oxygen.

NASA Hubble Space Telescope images of Ganymede's auroral belts (colored blue in this illustration) are overlaid on a Galileo orbiter image of the moon. The amount of rocking of the moon's magnetic field suggests that the moon has a subsurface saltwater ocean. Image Credit: NASA/ESA

Images of Ganymede’s auroral belts (colored blue in this illustration) are overlaid on a Galileo orbiter image of the moon. The amount of rocking of the moon’s magnetic field suggests that the moon has a subsurface saltwater ocean. The new observations were done in UV light, which can be seen by the Hubble in its orbit above Earth’s atmosphere. Credit: NASA/ESA

By watching the rocking motion of the two auroras, scientists were able to determine that a large amount of saltwater exists beneath Ganymede’s crust affecting its magnetic field.

Here’s how it works. If Ganymede DIDN’T have an ocean, changes in Jupiter’s magnetic field would cause the auroras to rock back and forth by 6°. But the conductive ocean fights Jupiter’s field so much, it reduces the rocking of the auroras to just 2°.

Jupiter’s magnetic field creates a secondary magnetic field within Ganymede’s soggy interior counter to the planet’s. Call it magnetic friction, but what a wonderfully imaginative way to probe a moon’s interior through study of its faint auroras.

Scientists studying how Ganymede's magnetic field (shown here as curved lines of magnetic force similar to iron filings around a magnet) NASA/European Space Agency

Scientists studying how Ganymede’s magnetic field (shown here as curved lines of magnetic force similar to iron filings around a magnet) interacts with Jupiter’s in the form of shifting auroras believe the moon harbors a large ocean. Credit: NASA/European Space Agency

“I was always brainstorming how we could use a telescope in other ways,” said Joachim Saur of the University of Cologne in Germany, who headed up the study using the Hubble Space Telescope. “Is there a way you could use a telescope to look inside a planetary body? Then I thought, the aurorae! Because aurorae are controlled by the magnetic field, if you observe the aurorae in an appropriate way, you learn something about the magnetic field. If you know the magnetic field, then you know something about the moon’s interior.”

“Brilliant!” as the Harry Potter character would say.

Scientists estimate the ocean is 60 miles (100 km) thick or 10 times deeper than Earth’s oceans. Now we can add Ganymede to the roster of extraterrestrial planets and moons – Mars, Europa and Enceladus – known to possess liquid water, one of life’s essential essences.

It’s double duo week: Moon-Jupiter and Venus-Uranus

The nearly full moon is in conjunction with Jupiter tonight. Their minimum separation of 5 happens around 10 p.m. (CST). Source: Stellarium

The nearly full moon is in conjunction with Jupiter tonight. Their minimum separation of 5° happens around 10 p.m. (CST). Source: Stellarium

I looked until around 11 p.m. last night but moonlight diluted any aurora that may have out. But the predicted storm did hit between about 2 a.m. and dawn this morning. While some readers might think I stay up all night, I really did sleep through this aurora. I know at least a few of you saw it. Tonight, there’s a chance for more minor storming.

There’s also an even better chance you’ll be struck by two very bright objects in the eastern sky at nightfall: a plump gibbous moon and the jolly giant planet Jupiter. They’ll be in conjunction tonight just ahead of Leo’s brightest star Regulus. Pairings like these make for great company and contemplation while walking the dog at night.

Venus and Uranus will be very close together on March 4th, an ideal time to find the fainter planet in binoculars. Source: Stellarium

Venus and Uranus will be very close together on March 4th, an ideal time to find the fainter planet in binoculars. Source: Stellarium

A planet-to-planet pairing occurs on Wednesday evening the 4th when Venus and Uranus will be just 1/3° apart. Like last month’s close graze with the crescent moon, this will provide yet another easy opportunity to see a planet that is too dim for most to see with the naked eye. Just point your binoculars at brilliant Venus in late twilight in the western sky and look for a tiny speck of light immediately below it.

I love how planets can appear so close and yet be so far from one another. Venus is a quick jaunt at 128 million miles from Earth compared to Uranus’ 1.9 billion miles, nearly 15 times farther away.

The stars in the constellation of Orion all look like they are at the same distance. Turn the constellation through 90 degrees and you can see the stars are actually at different distances. Two of the Belt stars plus the two bottom stars in the constellation are far from the sun but relatively near one another in space. Betelgeuse is much closer to us. Credit: ESA

The stars of Orion might be easily dismissed as all being at the same distance from us. That’s how they appear on the 2-D “surface” of the sky. Butturn the constellation through 90 degrees (look at it from the side) and you can see the true distances of each star. Notice that Betelgeuse is much closer to us than the Belt stars. Credit: ESA

When we see conjunctions and appreciate the real distances between objects in the sky, it’s helpful to remember the same applies to the constellations. We see familiar rectangular outline of Orion and the neat arrangement of his three belt stars by lucky chance. Looking back toward Orion’s stars from a different direction in space (a couple hundred light years beyond the solar system) Orion would be unrecognizable.

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)

Hubble snaps spectacular views of Jupiter triple transit

These new NASA/ESA Hubble Space Telescope images capture a rare occurrence as three of Jupiter’s largest moons parade across the giant gas planet’s banded face on January 23-24 this year. Credit: NASA/ESA/Hubble Heritage Team

Some of us saw the triple shadow transit last week and some battled clouds. The Hubble Space Telescope had a ringside seat 347 miles above the cloud deck. Wow, what a view!

At left, you can see all three shadows and two of the moons. The photo at right on the right shows the end of the event about 42 minutes later. Icy white Europa has entered Jupiter’s disk while Io’s shadow has moved off. Credit: NASA/ESA/Hubble Heritage Team

The photos are so sharp and detailed they hardly look real. Gorgeous stuff. Notice how sharply outlined each moon appears yet the shadows look fuzzy. Why? For the same reason your own shadow has a soft outline. The light source is the Sun, which even at Jupiter’s distance of over 400 million miles, still shows as a small disk and not a point.


Really cool time lapse of the triple shadow transit at Jupiter

Light from an extended disk creates shadows with blurred outlines because light from one side the disk or other “wraps around” around the edges of your body and partially tempers the darkness. Only a point source like Venus can create a shadow with a sharp border.

Io partially covers Callisto’s shadow, while at top is the shadow cast by Io. Credit: NASA/ESA/Hubble Heritage Team

Here’s one final image, a crop of the original. The colors and appearance look so unearthly.

 

 

 

 

 

Jupiter and the Full Moon make a lovely pair tonight

First, my apologies. Due to a system upgrade all the images from the blogs have been taken down temporarily, nor can I post any new ones. This hurts my soul but at least I can use these things called words.

In a nutshell,  there’s a really nice conjunction of Jupiter and the Full Snow Moon tonight. Just take a look out east when the sky gets dark and there they’ll be shining in tandem in Cancer the Crab. If you’d like to read a more complete explanation of the event and why it’s special beyond just looking plain beautiful, head over to Universe Today where you’ll find more information and some of the photos I’d hoped to use here. Thanks for hanging in there.

Triple shadow transit makes for triple the fun

Will Gator shot this excellent series of Jupiter portraits during different phases of the triple shadow transit last night and this morning with an 8-inch telescope. North is up and east to the left. In “D”, the top “dot” on the left side is the moon Callisto. The others are the shadows of (l-r) Europa, Callisto and Io. Credit: Will Gator

I had to dog last night’s triple shadow transit to see it but I’m glad I did. We had clouds nearly the entire time. But even with a crummy sky, Jupiter was bright enough to push through the ceiling at key times during the event.

Through the scope the planet drew a sharp profile with nice cloud belt detail. It was really fun to watch Io’s shadow catch up with and merge with Callisto’s shadow and then separate (panel C above). For a while the two looked like an headless ant or “negative double star”. Even more amazing was seeing the moon Io overlap Callisto’s shadow at 12:20 a.m.

For just a few minutes, Callisto’s black shadow turned a pale orange-gray, obviously lighter in tone than the neighboring shadow of Io. It simply looked wrong! Three minutes later Callisto returned as the biggest and most dominant shadow. Never seen anything like it.

When Europa squeezed onto the Jupiter’s disk at around 12:30 a.m. the show moved into high gear. It took a bit of concentration to see Europa as it casts the smallest shadow of the four Galilean moons. Just to its south, along the southern edge of the South Equatorial Belt, I could easily make out the moon Callisto. I managed about seven minutes of triple shadow viewing before the clouds became impenetrable.

After packing all the equipment away, I happily sat down and shared a glass of wine with my wife. Hope we’re all still around for 2032 when the next trifecta takes place.