Jupiter-moon conjunction / Space station expecting guests / Hello Mars!

Tomorrow morning September 20th the crescent moon will be lined up in conjunction with the planet Jupiter ahead of the Sickle of Leo. This view shows the sky a little more than an hour before sunrise. Stellarium

Getting a little extra sleep these September mornings? That benefit comes from later sunrises as we approach the fall equinox. I don’t know about you, but I sleep better in a darkened bedroom.

The rate of change has really picked up in the past few weeks with the sun now rising around 7 o’clock, a far cry from late June’s 5:15.

Later sunrises also mean a chance to catch an early morning sky event. Many of us are active around 6 a.m. prepping for work or getting your children ready for school. If you can find a few minutes to spare, tomorrow morning offers up two fine sights.

Look east in the brightening dawn and you’ll see a slender crescent moon in conjunction with the brightest of the planets, Jupiter. The two will just 5º apart meaning you’ll be able to squeeze three fingers held at arm’s length between them. Then, between 5:30-6:15 a.m. now through at least next week, the International Space Station (ISS) will be making regular passes across the northern sky from many locations across the U.S., Canada and Europe.

To find out exactly when and where to look, key in your zip code at Spaceweather’s Satellite Flybys site or select your city at Heavens Above. The ISS looks like the brightest “star” in the sky and travels from west to east. A typical complete pass takes about 5 minutes.

An earlier SpaceX Dragon capsule docking with the space station in March 2013. Astronauts will use the grapple arm to grab the capsule Monday morning Sept. 22 at around 6:30 a.m. CDT. Berthing begins around 8:45. Click to enlarge. Credit: NASA

The three current astronauts aboard the space station await the arrival of the other half of their crew next week. NASA astronaut Barry Wilmore, Soyuz Commander Alexander Samokutyaev and Flight Engineer Elena Serova will launch aboard their Soyuz spacecraft from the Baikonur Cosmodrome in Kazakhstan on Sept. 25 to begin a six-hour, four-orbit trek to the orbiting complex.

Before that, SpaceX’s unmanned Dragon ship will launch tomorrow morning Sept. 20 at 1:14 a.m. Central time to deliver cargo and crew supplies to the ISS early Monday morning Sept. 22nd.

Among the items are the first 3D printer in space, the ISS-RapidScat instrument to monitor ocean winds for climate research and weather forecasting and a commercial experiment designed to make a better golf club. The printer will allow astronauts to make their own tools and replacement parts that would otherwise cost a lot of money to ship up from Earth.

Fruit flies such as these spent one month aboard the International Space Station during an earlier study. More are on the way. Credit: NASA / Dominic Hart

20 female mice and 30 fruit flies will also go along for the ride. The mice will be housed in the new Rodent Research habitat, where they’ll be studied for the effects of spaceflight on the human body. In space, rodents don’t spend their time floating around. They’re very physically active but tend to hold onto the walls.

Fruit flies will be monitored for the effects of oxidative stress changes which happen in organisms ranging from fruit flies to humans. Oxidative stress involves a build up of harmful molecules inside cells that can cause cell damage, and it’s associated with infections and disease.

Artist view of India’s Mars orbiter at Mars. Arrival and orbit insertion is expected for Sept. 24. Credit: ISRO

There’s much more in the works for space mission news as Mars welcomes two new emissaries from Earth. NASA will insert the MAVEN spacecraft into orbit around Mars Sunday night, and India’s Mars Orbiter Mission (MOM) will arrive at the planet only three days later on Sept. 24.

The MAVEN mission will study Mars’ climate present and past as scientists try to figure out how the planet evolved from a warmer, wetter past to the current dry, cold desert. MOM is India’s first-ever mission to another planet. While primarily a demonstration and testing of that country’s technology, MOM will also photograph the Red Planet and study its mineral makeup from orbit.

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

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

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

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

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

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

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

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

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

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

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

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

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

Know your planet and eat it too

A Jupiter cake made by Rhiannon, who writes the Cakecrumbs blog, shows the giant planet’s layered atmosphere and interior in a fun and realistic way. Click for recipe. Credit: Rhiannon

I had no idea Jupiter had a mud cake core surrounded by almond butter cake and enveloped with a blue-tinted vanilla Madeira sponge. Topped off with vanilla buttercream and marshmallow icing, it’s the first planet that’s ever made my mouth water.

The Great Red Spot inspired Rhiannon to pick Jupiter for her cake. The iconic feature is instantly recognizable. She used ivory, brown and maroon edible ink to dry brush the Spot and other atmospheric features like belts and vortices on the outer layer of marshmallow fondant (icing). Credit: Rhiannon /cakecrumbs.me

Rhiannon, who writes the Cakecrumbs blog, had two passions as a child, animals and the solar system. A self-taught cook and cake decorator, she recently created what she calls her “Jupiter Structural Layer Cake” based on current knowledge of the planet’s atmosphere and interior.

Why Jupiter? It wouldn’t surprise you to know that the Great Red Spot – that huge storm more than twice the size of Earth that’s been whirling around up there the past few hundred years – has always been one of her favorite outer space personalities.

Jupiter concentric layer cake tutorial

Painting on the Red Spot and many other atmospheric details, all based on photos of the planet over many years, took 8 hours, just 2 hours shy of one complete rotation of the real Jupiter. That’s dedication.

You’ll have to watch the video to appreciate the details (three baking steps were required), but to create the sphere, she joined two cake hemispheres with buttercream.

The non-cake Jupiter spans nearly 87,000 miles across and is striped with jet-stream like belts of ammonia ice clouds. Earth is shown for comparison. Credit: NASA

Rhiannon cautions that her cake is “totally not to scale”, but she’s got the details down. Jupiter’s marshmallow cream atmosphere is mostly hydrogen and helium with clouds made of ammonia ice and even water ice further down. All those lovely yellows, reds and oranges so lovingly applied with tiny brushstrokes of food coloring are likely trace amounts of compounds of sulfur, carbon and phosphorus in real life.

Below the clouds, Jupiter just gets weird. Its atmosphere reaches down for thousands of miles. In December 1995, NASA’s Galileo spacecraft released an Entry Probe toward the planet. As the craft descended into the maelstrom of Jovian clouds, it transmitted data back to the orbiter for just 58 minutes. At a depth of 373 miles (600 km), transmissions stopped as the machine was presumably crushed by the extreme atmospheric pressure. Pressures at the base of Jupiter’s atmosphere are 4 million times what we experience on Earth.

Cutaway showing both the cloudtops and the interior of Jupiter. About 75% of the planet’s weight is taken up by fluid metallic hydrogen. Jupiter’s composition is very similar to the sun’s, and like the sun, it’s very hot in the center, but not hot enough to ignite hydrogen and burn as a star.

It only gets more intense as you approach the core. At a certain depth, airy hydrogen is compressed by the vast amount of material above it into liquid molecular hydrogen (the blue cake layer). Below that we arrive at a truly exotic form of matter, liquid metallic hydrogen (white cake).

Under the extreme pressures and heat near the core, ordinary hydrogen gets squeezed so tightly, its electrons depart and move about just like they do in metals. And just as metals conduct electricity, so too this bizarre hydrogen cousin. If you could somehow touch it – impossible because it can’t be created on Earth – it would resemble liquid mercury.

Don’t care for Jupiter? How about a slice of Earth? This is one of Rhiannon’s earlier cakes. The slice shows the crust, mantle (red), outer core (yellow) and inner core. Credit: Rhiannon / cakecrumbs.me

Jupiter’s intense magnetic field is thought to arise from the rapid spinning of this electric liquid. Deeper down, we meet a putative core of rock (mud cake), something like the Earth in composition, but 10-15 times more massive.

Have you had enough cake yet?


Miss the conjunction? Here’s your consolation prize

Clear skies prevailed over Königswinter, Germany for a great view of Venus and Jupiter just 0.2° apart at dawn this morning August 18. Credit: Daniel Fischer

Those killers of all things astronomical – clouds – were back again this morning, so no Venus-Jupiter conjunction here. Looks like I’ll pin my hopes on the one scheduled for next June 30 in Leo at dusk. I’m grateful for the flatness of the solar system, which guarantees that every few years we get repeat planet pairings.

Look east this coming Saturday morning for a sweet pairing of the bright planets and wiry crescent moon. This view shows the sky about 45 minutes before sunrise. Stellarium

I hope some of you got to see the conjunction from your home or on the way to work this morning. While Venus and Jupiter will now part ways, they’ll be one more blast of celestial awesomeness involving the duo and the crescent moon this weekend. Consider it a consolation prize. Who knows, this event might be even prettier than what passed this morning.

On Saturday morning, August 23rd about 30-45 minutes before sunrise, the thin, waning lunar crescent joins Jupiter and Venus in a stunning triangle of loveliness in the eastern sky.The threesome will all fit inside an 8° circle.

Now that I know this is coming I don’t feel so bad about missing the conjunction.

Two weeks of hell on Io

Last August, Jupiter’s moon Io experienced three massive volcanic eruptions within a two-week period. This Aug. 29, 2013 outburst on Io was among the largest ever observed. This image was taken in near-infrared light which shows the hot lava flows as bright blobs. Credit: Katherine de Kleer/UC Berkeley/Gemini Observatory

Little Io is the most volcanically active body in the solar system. Last August it made sure we were all aware of that fact with three great outbursts spread over just two weeks.

Ever since the twin probes Voyagers I and II passed the Jupiter system in 1979, we’ve known that the planet’s innermost large moon is literally bubbling with activity in the form of volcanic eruptions, fire fountains and sheets of hot lava spilling across its surface.

Eruption of Io’s Tvashtar volcano photographed by the New Horizons spacecraft in 2007. The plume reached about 102 miles (165 km) high.

With over 400 active volcanoes activity never ceases, but massive outbursts typically happen every one or two years … or so it was thought. Last August, to astronomers’ surprise, three massive volcanic eruptions occurred on Jupiter’s moon Io within a two-week period.

Io up close, photographed by the Galileo probe, shows numerous volcanoes and lava flows. Dark spots mark sites of current volcanic activity. Lava on the little moon can be as hot as 2,400°F (1,300°C), hotter than Earth’s peak of 2,190°F. Credit: NASA

“We typically expect one huge outburst every one or two years, and they’re usually not this bright,” said Imke de Pater, professor and chair of astronomy at the University of California, Berkeley, and lead author of one of two papers describing the eruptions. “Here we had three extremely bright outbursts, which suggest that if we looked more frequently we might see many more of them on Io.”

These images show Jupiter’s moon Io obtained at different infrared wavelengths (in microns, μm, or millionths of a meter) with the Keck Observatory’s 10-meter Keck II telescope on Aug. 15, 2013 (a-c), and the Gemini North telescope on Aug. 29, 2013 (d). Credit: Imke de Pater and Katherine de Kleer/UC Berkeley/Gemini/Keck

Only on Io do volcanoes spew lavas as intensely hot- hotter actually – as those found on Earth. Because of the moon’s low gravity, rock shot out of Io’s volcanoes can reach as high as several hundred kilometers, much higher than Earth’s best efforts (60-70 km).

“The amount of energy being emitted by these eruptions implies lava fountains gushing out of fissures at a very large volume per second, forming lava flows that quickly spread over the surface of Io,”  said Ashley Davies, volcanologist and colleague of de Pater.

Katherine de Kleer, a UC Berkeley graduate student, determined the temperature of the lavas released in the massive eruptions as likely hotter than lavas on present-day Earth but similar to what’s believed to have covered our planet shortly after its formation 4.5 billion years ago. Study of Io’s lava flows may help us understand how the surfaces of Earth, Venus and the moon were formed.

In Tupan Patera on Io, an island of solid sulfates floats atop a lake of hot, black lava. The feature is 50 miles (80 km) across and surrounded by a 2,950 foot high cliff. (900 meters). Credit: NASA

With it crazy mix of yellows, oranges and reds, Io’s often likened to a pizza, which seems very fitting especially if you’ve been burned by molten cheese dripping from the edge of your slice. The ‘cheese’ or lava on Io is molten sulfur and its compounds which give the its spectacular color palette.

Io’s volcanic activity is the result of a combination of gravitational forces:  Jupiter’s powerful gravity pulls it toward the planet while the moons Europa, Ganymede and Callisto pull it in the opposite direction. The opposing forces squeeze and stretch the hapless moon, causing its crust to rise and fall by 300 feet (100 meters). The tremendous friction generated heats and melts interior rocks to form lava that find its way to the surface through fissures in the crust. You’ll have to look hard to find any craters on Io as the crust has been resurfaced time and again by flows of molten rock.

Only about as big as Earth’s moon, Io is a clearly a horse of a different color all because it finds itself under very different circumstances.

Shhh! Don’t wake the sun

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

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

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

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

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

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

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

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

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

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

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

Farewell Jupiter, hello moon!

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Jupiter’s Red Spot shrinks to smallest size ever – how long will it last?

In this comparison image the photo at the top was taken by the Hubble Space Telescope in 1995 and shows the spot at a diameter of just under 13,050 miles (21,000 km); the second down shows a 2009 photo of the spot at a diameter of just under 11,180 miles (18,000 km); and the lowest shows the newest image from taken in 2014 with the spot at its smallest yet, with diameter of just 9,940 miles (16,000 km). Credit: NASA/ESA

The Great Red Spot is arguably Jupiter’s most iconic feature. Mention the giant planet and most of us conjure up an image of striped gas ball with a big red beauty mark.

While the spot has been observed since the infancy of the telescope, we’ve come to accept it as a permanent part of the Jovian planet’s persona. Now it’s time to admit the truth. The Great Red Spot has been downsizing since the 1930s with particularly swift changes happening in just the last couple decades.

Ask any long-time amateur astronomer. Back in the 1960s the spot extended over a greater area and was more elongated or stretched out. In the past few years, its not only contracted thousands of miles but become more circular. Most of us have blamed the spot’s pale, watered-down color in recent years as the reason it’s become more difficult to see.

At left, photo of Jupiter’s enormous Great Red Spot in 1879 from Agnes Clerk’s Book ” A History of Astronomy in the 19th Century”. At right, Jupiter on Jan. 10, 2014. Credit: Damian Peach

But that’s only part of the problem. Since 1995 it’s downsized by over 3,000 miles. That’s nearly half an Earth diameter in 20 years! Since 2012 it’s been losing girth at the rate of 580 miles a year. 130 years ago the spot spanned about 25,000 miles (40,000 km) and looked like a giant blimp riding Jupiter’s cloud belts. Even in the small 2-3 inch refracting telescopes popular at the time it would have hard to miss. Now you need at least a 6-inch telescope to see it clearly.

“In our new observations it is apparent very small eddies are feeding into the storm,” said Simon. “We hypothesized these may be responsible for the accelerated change by altering the internal dynamics and energy of the Great Red Spot,” said Amy Simon of NASA’s Goddard Space Flight Center.

Reprocessed view by Bjorn Jonsson of the Great Red Spot made by Voyager 1 in 1979 reveals an incredible wealth of detail. The Spot is a vast, long-lived. hurricane-like storm located between opposing jet streams in Jupiter’s southern hemisphere. Click to enlarge. Credit: NASA

The not-so Great Red Spot (GRS) is a hurricane-like storm that rotates anticlockwise in Jupiter’s southern hemisphere immediately south of the prominent South Equatorial Belt. It takes its swirly appearance from winds blowing at several hundred miles an hour with the spot’s cloudtops reaching 5 miles (8 km) above Jupiter’s cloud deck.

Animation showing the rotation of the Great Red Spot made with images taken by NASA’s Voyager 1 spacecraft . Credit: NASA

The spot used to rotate once every 6 days, but smaller eddies or vortices feeding into the spot that may be responsible for its changing appearance have shortened that to about 4 days.

Red Spot Jr. on Feb. 1, 2014. It’s the first significant new red spot ever observed on Jupiter and located at longitude 332 degrees (Sys. II) The spot about half the width of the more familiar Great Red Spot. Credit: Christopher Go

What will become of the spot is anyone’s guess. It may continue to wither and disappear altogether. It is does go bye-bye, Red Spot Jr. waits in the wings. This new but considerably smaller red-tinted spot formed from the merger of three smaller oval vortices between 1998 and 2000. Or we could be completely surprised and see it revivified by the Jovian jet streams. Such is weather, whether here or on Jupiter, there will always be an element of unpredictability.

NASA’s Juno spacecraft is hurtling toward Jupiter now, due to reach the giant planet in July 2016.  Up close examination by the probe will hopefully fill in holes in our knowledge of the planet’s turbulent and fascinating atmosphere.

Saturn disappears, Mercury appears during ‘night of the planets’

Saturn covered and uncovered by the moon earlier today by Dave Herald, Murrumbateman, Australia

Enjoy the video. Dave Herald did a great job recording this morning’s Saturn occultation. The images are very sharp. I always find it remarkable how atmosphere-less the moon is. There’s not a hint of softness in the planet as it’s devoured by the lunar limb. If there were substantial air, the planet would gradually soften and fade.

For a moon or planet to be completely without air is next to impossible. The solar wind knocks atoms from minerals on the lunar surface and sends them reeling into the virtual vacuum above the surface. Studies have found potassium, sodium, helium and argon in the moon’s exosphere, the name given to the lunar atmosphere. Bombardment of the moon’s surface rocks by micrometeorites and the solar wind release potassium and sodium; helium and argon probably bubble up from radioactive decay of those same rocks. Helium may also arrive via the sun’s wind.

Glow from sodium in the lunar atmosphere. The light from the moon has been blocked by the telescope, but the size, position and phase of the Moon are shown by the superimposed image in the center. Rayleighs are a measure of brightness. Credit: NASA

At sea level on Earth, we breathe in an atmosphere where each cubic centimeter contains 10,000,000,000,000,000,000 (10 quintillion) molecules; by comparison, the lunar atmosphere has less than a million molecules in the same volume.

Comets and meteoroids striking the surface temporarily enhance the amounts of other atoms and molecules. But the sum total of all the sputtering and interacting is an atmosphere equal to the amount of air you’ll find 250 miles high where the space station plies it orbit. Not much.

Mercury stands all by itself low in the northwest in this photo taken about 50 minutes after sunset last night. Credit: Bob King

At my house, we saw no occultation of Saturn, but the two did stand together in the southeastern sky at dusk. On the opposite end of the heavens, Mercury made a fine naked eye appearance in the northwestern sky.

Jupiter glows over Amity Creek last night. Both the creek and the sky were lit by the light of the full moon. Credit: Bob King

I first caught it around 9:15 p.m. some 40 minutes after sunset and watched it for at least a half hour. Capella and Jupiter – both higher up in a darker sky – made for great sight lines to the planet.See yesterday’s map for details.

Jupiter in Gemini remains the most brilliant object in the western sky at dusk during early evening hours. I watched it from a nearby creek that rushed with water from snow melt and recent rains.

Mars stood between Jupiter and Saturn. This week the ‘boring’ hemisphere – the one with fewest dark markings – is turned toward western hemisphere observers.

The Moon, Mars (upper right), Saturn (lower left), Spica (immediate right of moon) and Arcturus (top) as seen from Dayton, Ohio on May 12. Credit: John Chumack
Dayton, Ohio

But there’s still much to see – enough to easily stay up past your bedtime. The north polar cap on Mars remains visible despite the seasonal summer ‘heat’, and white clouds topping the planet’s major volcanoes are visible along the planet’s western edge. Check it out.