Jupiter Archives

January 29, 2017January 30, 2017 by Bob King

A Proposal For Juno To Observe The Volcanoes Of Io

Io and volcanic plume. Credit: NASA/JPL-Caltech

To accomplish its science objectives, NASA’s **Juno spacecraft** orbits over Jupiter’s poles and passes repeatedly through hazardous radiation belts. Two Boston University researchers propose using Juno to probe the ever-changing flux of volcanic gases-turned-ions spewed by Io’s volcanoes. Credit: NASA/JPL-Caltech

Jupiter may be the largest planet in the Solar System with a diameter 11 times that of Earth, but it pales in comparison to its own magnetosphere. The planet’s magnetic domain extends sunward at least 3 million miles (5 million km) and on the back side all the way to Saturn for a total of 407 million miles or more than 400 times the size of the Sun.

Jupiter’s large magnetic field interacts with the solar wind to form an invisible magnetosphere. If we were able to see it, it would span at least several degrees of sky. It would show its greatest extent when viewing Jupiter from the side at quadrature, when the planet stands due south at sunrise or sunset.In the artist’s depiction, the planet would be located between the two “purple eyes” — too small to see at this scale. Credit: NASA.

If we had eyes adapted to see the Jovian magnetosphere at night, its teardrop-like shape would easily extend across several degrees of sky! No surprise then that Jove’s magnetic aura has been called one of the largest structures in the Solar System.

A 5-frame sequence taken by the New Horizons spacecraft in May 2007 shows a cloud of volcanic debris from Io’s **Tvashtar volcano**. The plume extends some 200 miles (330 km) above the moon’s surface. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

Io, Jupiter’s innermost of the planet’s four large moons, orbits deep within this giant bubble. Despite its small size — about 200 miles smaller than our own Moon — it doesn’t lack in superlatives. With an estimated 400 volcanoes, many of them still active, Io is the most volcanically active body in the Solar System. In the moon’s low gravity, volcanoes spew sulfur, sulfur dioxide gas and fragments of basaltic rock up to 310 miles (500 km) into space in beautiful, umbrella-shaped plumes.

This schematic of Jupiter’s magnetic environments shows the planets looping magnetic field lines (similar to those generated by a simple bar magnet), Io and its plasma torus and flux tube. Credit: John Spencer / Wikipedia CC-BY-SA3.0 with labels by the author

Once aloft, electrons whipped around by Jupiter’s powerful magnetic field strike the neutral gases and ionize them (strips off their electrons). Ionized atoms and molecules (ions) are no longer neutral but possess a positive or negative electric charge. Astronomers refer to swarms of ionized atoms as plasma.

Jupiter rotates rapidly, spinning once every 9.8 hours, dragging the whole magnetosphere with it. As it spins past Io, those volcanic ions get caught up and dragged along for the ride, rotating around the planet in a ring called the Io plasma torus. You can picture it as a giant donut with Jupiter in the “hole” and the tasty, ~8,000-mile-thick ring centered on Io’s orbit.

That’s not all. Jupiter’s magnetic field also couples Io’s atmosphere to the planet’s polar regions, pumping Ionian ions through two “pipelines” to the magnetic poles and generating a powerful electric current known as the Io flux tube. Like firefighters on fire poles, the ions follow the planet’s magnetic field lines into the upper atmosphere, where they strike and excite atoms, spawning an ultraviolet-bright patch of aurora within the planet’s overall aurora. Astronomers call it Io’s magnetic footprint. The process works in reverse, too, spawning auroras in Io’s tenuous atmosphere.

The tilt of Juno’s orbit relative to Jupiter changes over the course of the mission, sending the spacecraft increasingly deeper into the planet’s intense radiation belts. Orbits are numbered from early in the mission to late. Credit: NASA/JPL-Caltech

Io is the main supplier of particles to Jupiter’s magnetosphere. Some of the same electrons stripped from sulfur and oxygen atoms during an earlier eruption return to strike atoms shot out by later blasts. Round and round they go in a great cycle of microscopic bombardment! The constant flow of high-speed, charged particles in Io’s vicinity make the region a lethal environment not only for humans but also for spacecraft electronics, the reason NASA’s Juno probe gets the heck outta there after each perijove or closest approach to Jupiter.

Io’s flux tube directs ions down Jupiter’s magnetic field lines to create magnetic footprints of enhanced aurora in Jupiter’s polar regions. An electric current of 5 million amps flows along Io’s flux tube.Credit: NASA/J.Clarke/HST

But there’s much to glean from those plasma streams. Astronomy PhD student Phillip Phipps and assistant professor of astronomy Paul Withers of Boston University have hatched a plan to use the Juno spacecraft to probe Io’s plasma torus to indirectly study the timing and flow of material from Io’s volcanoes into Jupiter’s magnetosphere. In a paper published on Jan. 25, they propose using changes in the radio signal sent by Juno as it passes through different regions of the torus to measure how much stuff is there and how its density changes over time.

The technique is called a radio occultation. Radio waves are a form of light just like white light. And like white light, they get bent or refracted when passing through a medium like air (or plasma in the case of Io). Blue light is slowed more and experiences the most bending; red light is slowed less and refracted least, the reason red fringes a rainbow’s outer edge and blue its inner. In radio occultations, refraction results in changes in frequency caused by variations in the density of plasma in Io’s torus.

The best spacecraft for the attempt is one with a polar orbit around Jupiter, where it cuts a clean cross-section through different parts of the torus during each orbit. Guess what? With its polar orbit, Juno’s the probe for the job! Its main mission is to map Jupiter’s gravitational and magnetic fields, so an occultation experiment jives well with mission goals. Previous missions have netted just two radio occultations of the torus, but Juno could potentially slam dunk 24.

New Horizons took this photo of Io in infrared light. The Tvastar volcano is bright spot at top. At least 10 other volcanic hot spots dot the moon’s night side. Credit: NASA/JHUPL/SRI

Because the paper was intended to show that the method is a feasible one, it remains to be seen whether NASA will consider adding a little extra credit work to Juno’s homework. It seems a worthy and practical goal, one that will further enlighten our understanding of how volcanoes create aurorae in the bizarre electric and magnetic environment of the largest planet.

January 25, 2017January 25, 2017 by Nancy Atkinson

Juno Just Took One Of The Best Images Of Jupiter Ever

A portion of a new image taken by the JunoCam imager on NASA’s Juno spacecraft of Jupiter’s northern latitudes on Dec. 11, 2016. Credit: NASA/JPL-Caltech/SwRI/MSSS/Gerald Eichstaedt/John Rogers.

Wow! If you’ve ever wanted to know what it would be like to hang above Jupiter’s clouds, here you go. This absolutely stunning view of Jupiter’s northern latitudes shows incredible detail of gas giant’s swirling cloudtops. And it features, in the lower left in the image below, the storm on the gas planet known as NN-LRS-1, or more colloquially, the Little Red Spot.

The JunoCam imager on NASA’s Juno spacecraft snapped this shot of Jupiter’s northern latitudes on Dec. 11, 2016. Credit: NASA/JPL-Caltech/SwRI/MSSS/Gerald Eichstaedt/John Rogers.

Juno’s JunoCam, a visible light camera, is able to get never-before-seen images like this because it is doing something that no other mission to Jupiter has done.

“The spacecraft’s proximity to Jupiter is very unusual,” Rick Nybakken told me during an interview at JPL last year. Nybakken is Juno’s project manager. “Juno has an elliptical orbit that brings it just 3,107 miles (5,000 km) above the cloud tops. No other mission has been this close, and we’re right on top of Jupiter so to speak.”

Special instruments are studying Jupiter’s radiation belt and magnetosphere, its interior structure, and the turbulent atmosphere, as well as providing views of the planet with spectacular, close-up images.

And another great thing about this image is that it was processed by citizen scientists. Gerald Eichstaedt and John Rogers processed the image and drafted the caption, and this will be the norm for many of the JunoCam images, because it’s “the public’s camera.”

“I’m excited though for what we’re doing with the visible light camera,” said Juno Project Scientist Steve Levin, who I also interviewed at JPL. “We’re making JunoCam as much as much as we possibly can an instrument that belongs to the public. We’ll solicit the aid of the public in picking which images to take, and releasing the data in its rawest form, and allow people to go and make the images.”

Scientist Candy Hansen is leading this citizen science effort, and she uses the phrase, “science in a fishbowl,” meaning the JunoCam team is showing people what it is like to do science by allowing anyone to participate and see the data as it arrives from Juno.

Damian Peach reprocessed one of the latest images taken by Juno’s JunoCam during its 3rd close flyby of the planet on Dec. 11. The photo highlights two large ‘pearls’ or storms in Jupiter’s atmosphere. Credit: NASA/JPL-Caltech/SwRI/MSSS

You can find the raw images here, so go ahead and test out your image processing skills.

JunoCam is designed to capture remarkable pictures of Jupiter’s poles and cloud tops. Although its images will be helpful to the science team to help provide context for the spacecraft’s other instruments, it is not considered one of the mission’s science instruments. JunoCam was included on the spacecraft specifically for purposes of engaging and including the public.

The Little Red Spot is the third largest anticyclonic oval on the planet, which Earth-based observers have tracked for the last 23 years. An anticyclone is a weather phenomenon with large-scale circulation of winds around a central region of high atmospheric pressure. They rotate clockwise in the northern hemisphere, and counterclockwise in the southern hemisphere. The Little Red Spot shows very little color these days, just a pale brown smudge in the center. Back in 2006, the storm was stronger and the color changed darker and more red. Now, with the storm not quite as active, the color is very similar to the surroundings, making it difficult to see.

If you’d like to download a larger version of this processed image (need a new wallpaper?) you can find it on NASA’s website.

December 15, 2016 by Bob King

Juno Captures a Stunning Jovian ‘Pearl’

New Juno image of Jupiter taken on Dec. 11, 2016. Processed by Damian Peach

Jupiter looks beautiful in pearls! This image, taken by the JunoCam imager on NASA’s Juno spacecraft, highlights one of the eight massive storms that from a distance form a ‘string of pearls’ on Jupiter’s turbulent atmosphere. They’re counterclockwise rotating storms that appear as white ovals in the gas giant’s southern hemisphere. The larger pearl in the photo above is roughly half the size of Earth. Since 1986, these white ovals have varied in number from six to nine with eight currently visible.

Four more 'pearls' in the string of eight photographed on Dec. 10, 2016. They show up well in photos but require good seeing and at least and 8-inch telescope to see. Credit: Christopher Go — Four more ‘pearls’ photographed on Dec. 10, 2016 in the planet’s South Temperate Belt below the Great Red Spot. The moon Ganymede is at left. The show up well in photos but require good seeing and at least and 8-inch telescope to see visually. Credit: **Christopher Go**

The photos were taken during Sunday’s close flyby. At the time of closest approach — called perijove — Juno streaked about 2,580 miles (4,150 km) above the gas giant’s roiling, psychedelic cloud tops traveling about 129,000 mph or nearly 60 km per second relative to the planet. Seven of Juno’s eight science instruments collected data during the flyby. At the time the photos were taken, the spacecraft was about 15,300 miles (24,600 km) from the planet.

This is the original image sent by JunoCam on Dec. 11 and shows the 8th of the eight oval or 'pearls'in Jupiter's roiling atmosphere. Credit: NASA/JPL-Caltech/SwRI/MSSS — This is the original image sent by JunoCam on Dec. 11 and features the eighth in a string of large storms in the planet’s southern hemisphere. Credit: NASA/JPL-Caltech/SwRI/MSSS

JunoCam is a color, visible-light camera designed to capture remarkable pictures of Jupiter’s poles and cloud tops. As Juno’s eyes, it will provide a wide view, helping to provide context for the spacecraft’s other instruments. JunoCam was included on the spacecraft specifically for purposes of public engagement; although its images will be helpful to the science team, it is not considered one of the mission’s science instruments.

4-frame animation spans 24 Jovian days, or about 10 Earth days. The passage of time is accelerated by a factor of 600,000. Credit: NASA — 4-frame animation spans 24 Jovian days, or about 10 Earth days. The passage of time is accelerated by a factor of 600,000. Some of the ovals are visible as well as a variety of jets – west to east and east to west. Credit: NASA

The crazy swirls of clouds we see in the photos are composed of ammonia ice crystals organized into a dozen or so bands parallel to the equator called belts (the darker ones) and zones. The border of each is bounded by a powerful wind flow called a jet, resembling Earth’s jet streams, which alternate direction from one band to the next.

Zones are colder and mark latitudes where material is upwelling from below. Ammonia ice is thought to give the zones their lighter color. Belts in contrast indicate sinking material; their color is a bit mysterious and may be due to the presence of hydrocarbons — molecules that are made from hydrogen, carbon, and oxygen as well as exotic sulfur and phosphorus compounds.

Use this guide to help you better understand Jupiter's arrangement of belts and zones, many of which are visible in amateur telescopes. Credit: NASA/JPL/Wikipedia — Use this guide to help you better understand Jupiter’s arrangement of belts and zones, many of which are visible in amateur telescopes. Credit: NASA/JPL/Wikipedia

The pearls or storms form in windy Jovian atmosphere and can last many decades. Some eventually dissipate while others merge to form even larger storms. Unlike hurricanes, which fall apart when they blow inland from the ocean, there’s no “land” on Jupiter, so storms that get started there just keep on going. The biggest, the Great Red Spot, has been hanging around causing trouble and delight (for telescopic observers) for at least 350 years.

Juno’s next perijove pass will happen on Feb. 2, 2017.

December 9, 2016 by David Dickinson

101 Astronomical Events for 2017: A Teaser

A partial solar eclipse rising over the VAB. Image by author.

It’s that time of year again… time to look ahead at the top 101 astronomical events for the coming year.

And this year ’round, we finally took the plunge. After years of considering it, we took the next logical step in 2017 and expanded our yearly 101 Astronomical Events for the coming year into a full-fledged guide book, soon to be offered here for free download on Universe Today in the coming weeks. Hard to believe, we’ve been doing this look ahead in one form or another now since 2009.

This “blog post that takes six months to write” will be expanded into a full-fledged book. But the core idea is the same: the year in astronomy, distilled down into the very 101 best events worldwide. You will find the best occultations, bright comets, eclipses and much more. Each event will be interspersed with not only the ‘whens’ and ‘wheres,’ but fun facts, astronomical history, and heck, even a dash of astronomical poetry here and there.

It was our goal to take this beyond the realm of a simple almanac or Top 10 listicle, to something unique and special. Think of it as a cross between two classics we loved as a kid, Burnham’s Celestial Handbook and Guy Ottewell’s Astronomical Calendar, done up in as guide to the coming year in chronological format. Both references still reside on our desk, even in this age of digitization.

And we’ve incorporated reader feedback from over the years to make this forthcoming guide something special. Events will be laid out in chronological order, along with a quick-list for reference at the end. Each event is listed as a one- or two-page standalone entry, ready to be individually printed off as needed. We will also include 10 feature stories and true tales of astronomy. Some of these were culled from the Universe Today archives, while others are new astronomical tales written just for the guide.

Don’t miss 2017’s only total solar eclipse, crossing the United States! Image credit: Michael Zeiler/The Great American Eclipse.

The Best of the Best

Here’s a preview of some of the highlights for 2017:

-Solar cycle #24 begins to ebb in 2017. Are we heading towards yet another profound solar minimum?

-Brilliant Venus reaches greatest elongation in January and rules the dusk sky.

-45P/Honda-Mrkos-Pajdusakova passes 0.08 AU from Earth on February 11^th, its closest passage for the remainder of the century.

-An annular solar eclipse spanning Africa and South America occurs on February 26^th.

A sample occultation map from the book. Image credit: Occult 4.1.2.

-A fine occultation of Aldebaran by the Moon on March 5^th for North America… plus more occultations of the star worldwide during each lunation.

-A total solar eclipse spanning the contiguous United States on August 21^st.

-A complex grouping of Mercury, Venus, Mars and the Moon in mid-September.

-Saturn’s rings at their widest for the decade.

Getting wider... the changing the of Saturn's rings. Image credit and copyright: Andrew Symes (@FailedProtostar). — Getting wider… the changing face of Saturn’s rings. Image credit and copyright: Andrew Symes (@FailedProtostar).

-A fine occultation of Regulus for North America on October 15^th, with occultations of the star by the Moon during every lunation for 2017.

-Asteroid 335 Roberta occults a +3^rd magnitude star for northern Australia…

And that’s just for starters. Entries also cover greatest elongations for the inner planets and oppositions for the outer worlds, the very best asteroid occultations of bright stars, along with a brief look ahead at 2018.

Get ready for another great year of skywatching!

And as another teaser, here’s a link to a Google Calendar download of said events, complied by Chris Becke (@BeckePhysics). Thanks Chris!

October 21, 2016 by Bob King

Astronomers Think They Know Where Rosetta’s Comet Came From

In the distant past, the orbit of 67P/Churyumov-Gerasimenko extended far beyond Neptune into the refrigerated Kuiper Belt. Interactions with the gravitational giant Jupiter altered the comet's orbit over time, dragging it into the inner Solar System. Credit: Western University, Canada

Rosetta’s Comet hails from a cold, dark place. Using statistical analysis and scientific computing, astronomers at Western University in Canada have charted a path that most likely pinpoints comet 67P/Churyumov-Gerasimenko’s long-ago home in the far reaches of the Kuiper Belt, a vast region beyond Neptune home to icy asteroids and comets.

According to the new research, Rosetta’s Comet is relative newcomer to the inner parts of our Solar System, having only arrived about 10,000 years ago. Prior to that, it spent the last 4.5 billion years in cold storage in a rough-and-tumble region of the Kuiper Belt called the scattered disk.

The Kuiper Belt was named in honor of Dutch-American astronomer Gerard Kuiper, who postulated a reservoir of icy bodies beyond Neptune. The first Kuiper Belt object was discovered in 1992. We now know of more than a thousand objects there, and it's estimated it's home to more than 100,000 asteroids and comets there over 62 miles (100 km) across. Credit: JHUAPL — The Kuiper Belt was named in honor of Dutch-American astronomer Gerard Kuiper, who postulated a reservoir of icy bodies beyond Neptune. The first Kuiper Belt object was discovered in 1992. We now know of more than a thousand objects there, and it’s estimated it’s home to more than 100,000 asteroids and comets there over 62 miles (100 km) across. Credit: JHUAPL

In the Solar System’s youth, asteroids that strayed too close to Neptune were scattered by the encounter into the wild blue yonder of the disk. Their orbits still bear the scars of those long-ago encounters: they’re often highly-elongated (shaped like a cigar) and tilted willy-nilly from the ecliptic plane up to 40°. Because their orbits can take them hundreds of Earth-Sun distances into the deeps of space, scattered disk objects are among the coldest places in the Solar System with surface temperatures around 50° above absolute zero. Ices that glommed together to form 67P at its birth are little changed today. Primordial stuff.

Watch how Rosetta’s Comet’s orbit has evolved since the comet’s formation

There are two basic comet groups. Most comets reside in the cavernous Oort Cloud, a roughly spherical-shaped region of space between 10,000 and 100,000 AU (astronomical unit = one Earth-Sun distance) from the Sun. The other major group, the Jupiter-family comets, owes its allegiance to the powerful gravity of the giant planet Jupiter. These comets race around the Sun with periods of less than 20 years. It’s thought they originate from collisions betwixt rocky-icy asteroids in the Kuiper Belt.

Fragments flung from the collisions are perturbed by Neptune into long, cigar-shaped orbits that bring them near Jupiter, which ropes them like calves with its insatiable gravity and re-settles them into short-period orbits.

Comet 67P/Churyumov-Gerasimenko is a Jupiter-family comet. Its 6.5 year journey around the Sun takes it from just beyond the orbit of Jupiter at its most distant, to between the orbits of Earth and Mars at its closest. Credit: ESA with labels by the author — Comet 67P/Churyumov-Gerasimenko is a Jupiter-family comet. Its 6.5 year journey around the Sun takes it from just beyond the orbit of Jupiter at its most distant to between the orbits of Earth and Mars at its closest. Credit: ESA with labels by the author

Mattia Galiazzo and solar system expert Paul Wiegert, both at Western University, showed that in transit, Rosetta’s Comet likely spent millions of years in the scattered disk at about twice the distance of Neptune. The fact that it’s now a Jupiter family comet hints of a possible long-ago collision followed by gravitational interactions with Neptune and Jupiter before finally becoming an inner Solar System homebody going around the Sun every 6.45 years.

By such long paths do we arrive at our present circumstances.

October 20, 2016 by Evan Gough

No, There Won’t Be 15 Days of Darkness in November. It’s Another Stupid Hoax.

Venus and Jupiter at dusk over Australia's Outback on June 27, 2015. Credit: Joseph Brimacombe

The internet is great, isn’t it?

You can post anything you want on the internet, and if people like the sound of it, they spread it. It doesn’t make any difference if it’s true or not. We’re not born fact checkers and skeptics, are we?

Pretty soon, before you know it, it’s gone viral. Then it becomes its own sensation, and people who don’t even believe it start reporting it. Never is this more true than with hoaxes.

The latest hoax is the “15 Days of Darkness in November” thing that’s going around. Everyone’s on the bandwagon.

The 15 days hoax is not new. It made an appearance last year, and was thoroughly debunked. And of course, there wasn’t 15 day of darkness last year, was there? (Unless NASA covered it up!)

It’s here again this year, and will be debunked again, and will probably be here next year, too.

The whole thing started at a site that will remain linkless, and caught on from there. This is what the site reported:

“NASA has confirmed that the Earth will experience 15 days of total darkness between November 15 and November 29, 2015. The event, according to NASA, hasn’t occurred in over 1 Million years.”

Of course, NASA never said any such thing.

Here is supposedly what will happen to cause this calamity. Try and follow along with the nonsensical foolishness.

During the conjunction between Venus and Jupiter on October 26, light from Venus would cause gases in Jupiter to heat up. The heated gasses will cause a large amount of hydrogen to be released into space. The gases will reach the Sun and trigger a massive explosion on the surface of the star, heating it to 9,000 degrees Kelvin. The heat of the explosion would then cause the Sun to emit a blue color.
The dull blue color will last for 15 days during which the Earth will be thrown into darkness.

Where to begin? Let’s start with conjunctions.

Conjunctions are mostly just visual phenomena. The fact that two things in the sky look closer together from our point of view on Earth doesn’t mean that they’re that close together. In fact, even when Jupiter and Venus are in conjunction, they can still be over 800 million km apart. For perspective, the Sun and the Earth are about 150 million km apart.

So, as the hoax goes, at that great distance, light from Venus will cause gases on Jupiter to heat up. News Flash: the light from the Sun is far more intense than light from Venus could ever be, and it doesn’t heat up the gases on Jupiter. In fact, any light from Venus that makes it to Jupiter is just reflected sunlight anyway.

The Moon and this dead tree are in conjunction. This will cause the Martian Pyramids to vibrate harmonically. These vibrations will shake the walls of the movie studio where the Moon landing was faked, causing it to collapse. Image: Evan Gough

The hoax gets more outrageous as it goes along. These supposed heated gases then escape from Jupiter into space, and head for the Sun. But Jupiter is enormous and has enormous gravitational pull. How are any gases going to escape Jupiter’s overpowering gravity? Answer: they can’t and they won’t.

Then, these gases supposedly strike the Sun, and trigger a massive explosion on the Sun’s surface, which turn the Sun blue and plunges the Earth into darkness. Not blueness, which I could understand, but darkness.

This is absurd, of course. The Sun dominates the planets in a one-way relationship, and nothing the planets ever do could change that. No escaped gases from Jupiter would ever strike the Sun.

Jupiter is puny and insignificant compared to the Sun. And it's also hundreds of millions of kilometers away. How is a puny puff of hydrogen from Jupiter supposed to darken the Sun? Image: NASA/SDO — Jupiter is puny and insignificant compared to the Sun. And it’s also hundreds of millions of kilometers away. How is a puny puff of hydrogen from Jupiter supposed to darken the Sun? Image: NASA/SDO

Nothing Jupiter does can affect the Sun. Jupiter is, on average, 778 million km from the Sun. Jupiter could change places with Venus, and the Sun would keep shining normally. Jupiter could explode completely and the Sun would go on shining normally. Jupiter could put on a big red nose and some clown shoes, and the Sun would remain unaffected.

The Sun is a giant atom-crushing machine 1000 times more massive than Jupiter. The massive wall of energy and solar wind that comes from the Sun slams into Jupiter, and completely overwhelms anything Jupiter can do to the Sun. It’s just the way it is. It’s just the way it will always be.

Like the faked Moon landing hoax, and the Nibiru/Planet X hoax, this 15 days of darkness meme just keeps coming around. There may be no end to it.

It’s annoying, for sure, but maybe there’s a silver lining. Maybe some people reading about this supposed calamity will enter the word “conjunction” into a search engine, and begin their own personal journey of learning how the universe works.

We can hope so, can’t we?

October 5, 2016October 5, 2016 by David Dickinson

Seeing Double: Jupiter Returns at Dawn

Missing Jove? The largest planet in our solar system is currently on the far side of the Sun and just passed solar conjunction on September 26^th, 2016. October now sees Jupiter slowly return to the dawn sky. Follow that gas giant, as an interesting set of double shadow transits transpires in late October leading in to early November.

This particular cycle of double shadow transits involves the large Jovian moons of Europa and Ganymede.

The scene on October 24th at 23:55 UT. Image credit: Created using Starry Night Education software.

Europa and Ganymede double shadow transit season begins later this month, as both cast shadows on the Jovian cloud tops. This series of simultaneous shadow transits runs from October 17^th to November 8^th, and includes four weekly events.

The inner three large moons Io, Europa and Ganymede are in a 4:2:1 resonance. Europa orbits Jove once every 3.6 days and makes two circuits for Ganymede’s one. This means there’s a double shadow transit once every week in the current season:

The double shadow transit season of 2016. Created by author.

When can you first spy Jupiter, post solar conjunction? Catching this particular series of double shadow transits is challenging this time around, owing to the planet’s position low in the dawn twilight. The first event on October 17^th starts with Jupiter just 16 degrees west of the Sun, and the cycle ends with Jove 38 degrees west of the Sun on November 8^th.

Keep in mind, it is possible to track Jupiter up in to the daytime sky, post sunrise. To do this, you’ll need a ‘scope with a solid equatorial mount and good sidereal tracking. The trick is to lock on to Jupiter before sunrise and track it up in to the dawn sky. Be sure to physically block that dazzling rising Sun out of view behind a hill or building, and NEVER aim your telescope at the Sun!

Using this method opens up the possibility of nabbing a given double shadow event to longitudes due east of the quoted locales above.

The waning crescent Moon also passes 1.4 degrees NNE of Jupiter on October 28^th, offering another chance to spy the gas giant in the dawn sky, using the nearby crescent Moon as a guide.

The Moon and Jupiter in the daytime skies on Novemebr. — The Moon and Jupiter in the daytime skies on October 28th. Image credit: Stellarium.

And another interesting pairing is coming right up on the morning of Tuesday, October 11^th, when Mercury passes just 0.8 degrees (48′) NNE of Jupiter. Both are only 12 degrees west of the Sun at closest approach, which occurs around 10:00 UT. Still, both will appear as an interesting pseudo-double star, with Mercury shining at magnitude -1.1 and Jupiter only half a magnitude fainter at -1.6.

You can even see Jupiter coming off of solar conjunction and headed toward dawn skies courtesy of SOHO’s LASCO C3 camera:

Jupiter (arrowed) exiting the 15 degree wide field of view of SOHO's LASCO C3 camera on October 5th. Image credit: NASA/ESA/SOHO. — Jupiter (arrowed) exiting the 15 degree wide field of view of SOHO’s LASCO C3 camera on October 5th. Image credit: NASA/ESA/SOHO.

Callisto, the outermost large moon of Jupiter, ceased casting its shadow on Jupiter earlier this year on September 1^st 2016. Callisto is the only large moon that can ‘miss’ the gas giant’s cloud tops. Callisto must be involved for a triple shadow transit to occur, and the moon resumes regularly casting its shadow on Jove on December 4th, 2019.

Callisto can also experience total solar eclipses similar to those seen from the Earth during the mutual eclipse season for Jupiter’s moons, albeit shorter in duration:

And don ‘t forget: we’ve got a spacecraft currently exploring Jupiter for the next year and a half: NASA’s very own Juno.

Be sure to check out the Jovian action over the next month, gracing a dawn sky near you.

September 2, 2016October 5, 2016 by Evan Gough

Juno Captures Jupiter’s Enthralling Poles From 2,500 Miles

JunoCam captured this image of Jupiter's north pole region from a distance of 78,000 km (48,000 miles) above the planet.

Juno is sending data from Jupiter back to us, courtesy of the Deep Space Network, and the first images are meeting our hyped-up expectations. On August 27, the Juno spacecraft came within about 4,200 km. (2,500 miles) of Jupiter’s cloud tops. All of Juno’s instruments were active, and along with some high-quality images in visual and infrared, Juno also captured the sound that Jupiter produces.

Juno has captured the first images of Jupiter’s north pole. Beyond their interest as pure, unprecedented eye candy, the images of the pole reveal things never before seen. They show storm activity and weather patterns that are seen nowhere else in our solar system. Even on the other gas giants.

“…like nothing we have seen or imagined before.”

“First glimpse of Jupiter’s north pole, and it looks like nothing we have seen or imagined before,” said Scott Bolton, principal investigator of Juno from the Southwest Research Institute in San Antonio. “It’s bluer in color up there than other parts of the planet, and there are a lot of storms. There is no sign of the latitudinal bands or zone and belts that we are used to — this image is hardly recognizable as Jupiter. We’re seeing signs that the clouds have shadows, possibly indicating that the clouds are at a higher altitude than other features.”

The iconic storm bands of Jupiter are absent in this JunoCam image of Jupiter's northern polar region. Instead, the region is dominated by swirling storm patterns reminiscent of hurricanes here on Earth. Image: NASA/JPL-Caltech/SwRI/MSSS — The iconic storm bands of Jupiter are absent in this JunoCam image of Jupiter’s northern polar region. Instead, the region is dominated by swirling storm patterns reminiscent of hurricanes here on Earth. Image: NASA/JPL-Caltech/SwRI/MSSS

The visible light images of Jupiter’s north pole are very different from our usual perception of Jupiter. People have been looking at Jupiter for a long time, and the gas giant’s storm bands, and the Great Red Spot, are iconic. But the north polar region looks completely different, with whirling, rotating storms similar to hurricanes here on Earth.

The Junocam instrument is responsible for the visible light pictures of Jupiter that we all enjoy. But the Jovian Infrared Auroral Mapper (JIRAM) is showing us a side of Jupiter that the naked eye will never see.

The Juno Infrared Auroral Mapper (JIRAM) captured this infrared image of Jupiter's south pole. This part of Jupiter cannot be seen from Earth. Image: NASA/JPL-Caltech/SwRI/MSSS — The Juno Infrared Auroral Mapper (JIRAM) captured this infrared image of Jupiter’s south pole. This part of Jupiter cannot be seen from Earth. Image: NASA/JPL-Caltech/SwRI/MSSS

“JIRAM is getting under Jupiter’s skin, giving us our first infrared close-ups of the planet,” said Alberto Adriani, JIRAM co-investigator from Istituto di Astrofisica e Planetologia Spaziali, Rome. “These first infrared views of Jupiter’s north and south poles are revealing warm and hot spots that have never been seen before. And while we knew that the first-ever infrared views of Jupiter’s south pole could reveal the planet’s southern aurora, we were amazed to see it for the first time.”

“No other instruments, both from Earth or space, have been able to see the southern aurora.”

Even when we’re prepared to be amazed by what Juno and other spacecraft show us, we are still amazed. It’s impossible to see Jupiter’s south pole from Earth, so these are everybody’s first glimpses of it.

“No other instruments, both from Earth or space, have been able to see the southern aurora,” said Adriani. “Now, with JIRAM, we see that it appears to be very bright and well-structured. The high level of detail in the images will tell us more about the aurora’s morphology and dynamics.”

Beyond the juicy images of Jupiter are some sound recordings. It’s been known since about the 1950’s that Jupiter is a noisy planet. Now Juno’s Radio/Plasma Wave Experiment (WAVE) has captured a recording of that sound.

“Jupiter is talking to us in a way only gas-giant worlds can,” said Bill Kurth, co-investigator for the Waves instrument from the University of Iowa, Iowa City. “Waves detected the signature emissions of the energetic particles that generate the massive auroras which encircle Jupiter’s north pole. These emissions are the strongest in the solar system. Now we are going to try to figure out where the electrons come from that are generating them.”

Oddly enough, that’s pretty much exactly what I expected Jupiter to sound like. Like something from an early sci-fi film.

There’s much more to come from Juno. These images and recordings of Jupiter are just the result of Juno’s first orbit. There are over 30 more orbits to come, as Juno examines the gas giant as it orbits beneath it.

August 28, 2016August 29, 2016 by Ken Kremer

JUNO Transmits First Up-Close Look Soarin’ over Jupiter

Jupiter's north polar region is coming into view as NASA's Juno spacecraft approaches the giant planet. This view of Jupiter was taken on August 27, when Juno was 437,000 miles (703,000 kilometers) away. Credits: NASA/JPL-Caltech/SwRI/MSSS

NASA’s JUNO spacecraft successfully swooped over the Jovian cloud tops today, Saturday, Aug. 27, gathering its first up close images and science observations of the ‘King of the Planets’ since braking into orbit on America’s Independence Day.

Saturdays’ close encounter with Jupiter soaring over its north pole was the first of 36 planned orbital flyby’s by Juno during the scheduled 20 month long prime mission.

“Soarin’ over #Jupiter. My 1st up-close look of the gas-giant world was a success!” the probe tweeted today post-flyby.

NASA released Juno’s first up-close image taken by the JunoCam visible light camera just hours later – as seen above.

Juno was speeding at some 130,000 mph (208,000 kilometers per hour) during the time of Saturday’s closest approach at 9:44 a.m. EDT (6:44 a.m. PDT 13:44 UTC) over the north polar region.

It passed merely 2,600 miles (4,200 kilometers) above the turbulent clouds of the biggest planet in our solar system during its initial 53.5 day polar elliptical capture orbit.

And apparently everything proceeded as the science and engineering team leading the mission to the gas giant had planned.

“Early post-flyby telemetry indicates that everything worked as planned and Juno is firing on all cylinders,” said Rick Nybakken, Juno project manager at NASA’s Jet Propulsion Laboratory in Pasadena, California, in a statement.

This dual view of Jupiter was taken on August 23, when NASA's Juno spacecraft was 2.8 million miles (4.4 million kilometers) from the gas giant planet on the inbound leg of its initial 53.5-day capture orbit. Credit: NASA/JPL-Caltech/SwRI/MSSS — This dual view of Jupiter was taken on August 23, when NASA’s Juno spacecraft was 2.8 million miles (4.4 million kilometers) from the gas giant planet on the inbound leg of its initial 53.5-day capture orbit. Credit: NASA/JPL-Caltech/SwRI/MSSS

Indeed Saturday’s encounter will count as the closest of the entire prime mission. It also marks the first time that the entire suite of nine state-of-the-art science instruments had been turned on to gather the totally unique observations of Jupiter’s interior and exterior environment.

“We are getting some intriguing early data returns as we speak,” said Scott Bolton, principal investigator of Juno from the Southwest Research Institute in San Antonio, in a statement.

“This is our first opportunity to really take a close-up look at the king of our solar system and begin to figure out how he works.”

Additional up-close high resolution imagery of the Jovian atmosphere, swirling cloud tops and north and south poles snapped by JunoCam will be released in the coming weeks, perhaps as soon as next week.

“We are in an orbit nobody has ever been in before, and these images give us a whole new perspective on this gas-giant world,” said Bolton.

“It will take days for all the science data collected during the flyby to be downlinked and even more to begin to comprehend what Juno and Jupiter are trying to tell us.”

The prime mission is scheduled to end in February of 2018 with a suicide plunge into the Jovian atmosphere to prevent any possible contamination with Jupiter’s potentially habitable moons such as Europa and Ganymede.

“No other spacecraft has ever orbited Jupiter this closely, or over the poles in this fashion,” said Steve Levin, Juno project scientist from NASA’s Jet Propulsion Laboratory in Pasadena, California. “This is our first opportunity and there are bound to be surprises. We need to take our time to make sure our conclusions are correct.”

The team did release an approach image taken by JunoCam on Aug. 23 when the spacecraft was 2.8 million miles (4.4 million kilometers) from the gas giant planet on the inbound leg of its initial 53.5-day capture orbit.

One additional long period orbit is planned. The main engine will fire again in October to reduce the orbit to the 14 day science orbit.

Animation of Juno 14-day orbits starting in late 2016. Credits: NASA/JPL-Caltech

The solar powered probe will collect unparalleled new data that will unveil the hidden inner secrets of Jupiter’s origin and evolution as it peers “beneath the obscuring cloud cover of Jupiter and study its auroras to learn more about the planet’s origins, structure, atmosphere and magnetosphere.”

The $1.1 Billion Juno was launched on Aug. 5, 2011 from Cape Canaveral Air Force Station, Florida atop the most powerful version of the Atlas V rocket augmented by 5 solid rocket boosters and built by United Launch Alliance (ULA). That same Atlas V 551 version recently launched MUOS-5 for the US Navy on June 24.

The Juno spacecraft was built by prime contractor Lockheed Martin in Denver.

Illustration of NASA's Juno spacecraft firing its main engine to slow down and go into orbit around Jupiter. Lockheed Martin built the Juno spacecraft for NASA's Jet Propulsion Laboratory. Credit: NASA/Lockheed Martin — Illustration of NASA’s Juno spacecraft firing its main engine to slow down and go into orbit around Jupiter. Lockheed Martin built the Juno spacecraft for NASA’s Jet Propulsion Laboratory. Credit: NASA/Lockheed Martin

The last NASA spacecraft to orbit Jupiter was Galileo in 1995. It explored the Jovian system until 2003.

In the final weeks of the approach before Jupiter Orbit Insertion (JOI), JunoCam captured dramatic views of Jupiter and all four of the Galilean Moons moons — Io, Europa, Ganymede and Callisto.

At the post JOI briefing at JPL on July 5, these were combined into a spectacular JunoCam time-lapse movie released by Bolton and NASA.

Watch and be mesmerized -“for humanity, our first real glimpse of celestial harmonic motion” says Bolton.

Video caption: NASA’s Juno spacecraft captured a unique time-lapse movie of the Galilean satellites in motion about Jupiter. The movie begins on June 12th with Juno 10 million miles from Jupiter, and ends on June 29th, 3 million miles distant. The innermost moon is volcanic Io; next in line is the ice-crusted ocean world Europa, followed by massive Ganymede, and finally, heavily cratered Callisto. Galileo observed these moons to change position with respect to Jupiter over the course of a few nights. From this observation he realized that the moons were orbiting mighty Jupiter, a truth that forever changed humanity’s understanding of our place in the cosmos. Earth was not the center of the Universe. For the first time in history, we look upon these moons as they orbit Jupiter and share in Galileo’s revelation. This is the motion of nature’s harmony. Credits: NASA/JPL-Caltech/MSSS

Stay tuned here for Ken’s continuing Earth and Planetary science and human spaceflight news.

Ken Kremer

United Launch Alliance Atlas V liftoff with NASA’s Juno to Jupiter orbiter on Aug. 5, 2011 from Cape Canaveral Air Force Station, Florida. Credit: Ken Kremer/kenkremer.com

August 22, 2016 by Bob King

5 Days, 2 Spectacular Conjunctions

Two planets close and up close. This is the view through a telescope during the extremely close conjunction of Jupiter and Venus on August 27. Credit: Stellarium

Saturn, Mars and Antares are shown on Sunday night August 21 two nights before their lineup. Mars is still far and away the brightest object in the bunch at magnitude -0.5. Details: 35mm lens, f/2.8, ISO 400, 10 seconds. Credit: Bob King — Saturn, Mars and Antares are shown on Sunday night August 21 two nights before their lineup. Mars is still the brightest of the bunch at magnitude –0.5. It will with Saturn at +0.4 and Antares at +1.0. Details: 35mm lens, f/2.8, ISO 400, 10 seconds. Credit: Bob King

Conjunctions of bright planets make for jewelry in the sky. This week, get ready for some celestial shimmer. If you’ve been following the hither and thither of Mars and Saturn near Antares this summer, you know these planets have been constantly on the move, creating all kinds of cool alignments in the southern sky.

On Tuesday night (August 23) the hopscotching duo will fall in line atop Antares in the southwestern sky at nightfall. Mars will sit just 1.5° above the star and Saturn 4° above Mars. Viewed from the Americas and Europe, the line will appear slightly bent. To catch them perfectly lined up, you’ll have to be in central Asia on the following evening, but the view should be pleasing no matter where you live.

This will be the scene facing south at nightfall from the central U.S. on Tuesday night August 23. The two planets and star form a compact gathering that's sure to grab your attention. Credit: Stellarium — This will be the scene facing southwest at nightfall from the central U.S. on Tuesday night August 23. The two planets and star form a compact gathering that’s sure to grab your attention. The moment of conjunction between Mars and Saturn occurs at 11:00 UT (7 a.m. Eastern Aug. 24), but they’ll be below the horizon at that time for the Americas and Europe. Credit: Stellarium

Nice as it is, the Mars-Saturn-Antares lineup is only the warm-up for the big event: the closest conjunction of the two brightest planets this year. On Saturday evening, August 27, Venus and Jupiter will approach within a hair’s breadth of each other as viewed with the naked eye — only 0.1° will separate the two gems. That’s one-fifth of a full moon’s width! While Mars and Saturn will be a snap to spot low in the southwestern sky during their conjunction, Venus and Jupiter snuggle near the western horizon at dusk.

Look for Venus and Jupiter right next to each other 4 degrees (about three fingers held together horizontally) above the western horizon about a half-hour after sunset on August 27. Map: Bob King; source: Stellarium — Look for Venus and Jupiter right next to each other 4° (about three fingers held together horizontally) above the western horizon about a half-hour after sunset on August 27. This map shows the view from across the central U.S. at about 40°N latitude. The two planets will be closest at 22:00 UT (6 p.m. Eastern, 7 p.m. Central, 8 p.m. Mountain and 9 p.m. Pacific). Map: Bob King; source: Stellarium

To make sure you see them, find a place in advance of the date with a wide open view to the west. I also suggest bringing a pair of binoculars. It’s so much easier to find an object in bright twilight with help from the glass. You can start looking about 25 minutes after sunset; Venus will catch your eye first. Once you’ve found it, look a smidge to its lower right for Jupiter. If you’re using binoculars, lower them to see how remarkably close the two planets appear using nothing but your eyeballs. Perhaps they’ll remind you of a bright double star in a telescope or even the twin suns of Tatooine in Star Wars.

Here's what the two planets will look like through a telescope at medium and high magnification, when both will comfortably fit into the same field of view. Stellarium — The two planets will be only 6 arc minutes apart Saturday evening and easily fit in the same field of view of a telescope at high magnification. Jupiter’s four brightest moons will be obvious. If you’re patient and wait for the air to settle, you’ll be able to make out Venus’s waxing gibbous phase. Credit: Stellarium

Have a small telescope? Take it along — Jupiter and Venus are so close together that they easily fit in the same high magnification field of view. Jupiter’s four brightest moons will be on display, and Venus will look just like a miniature version of the waxing gibbous moon. Rarely do the sky’s two brightest planets nearly fuse, making this a not-to-miss event.

Venus and Jupiter do a little square dance over the nights of August 26-28. Jupiter is headed westward toward conjunction with the sun, while Venus is moving away from the sun from our perspective. Stellarium — Venus and Jupiter do a little square dance over the nights of August 26-28. Jupiter is headed westward toward conjunction with the sun, while Venus is moving away from the sun in the opposite direction from our perspective. Credit: Stellarium

If cloudy weather’s in the forecast that night, you can still spot them relatively close together the night before and night after, when they’ll be about 1° or two full moon diameters apart. I get pretty jazzed when bright objects approach closely in the sky, and I’m betting you do, too.

I also don’t mind being taken in by illusion once in a while. During a conjunction, planets only appear close together because we view them along the same line of sight. Their real distances add a dose of reality.

On Saturday evening Venus will be 143 million miles (230 million km) away vs. 592 million miles (953 million km) for Jupiter. In spite of appearing to almost touch, Jupiter is more than four times farther than the goddess planet.

The showpieces in this week's conjunction parade: Jupiter, Venus, Mars and Saturn. Credit: NASA/ESA — The showpieces in this week’s conjunction parade: Jupiter, Venus, Mars and Saturn. Credit: NASA/ESA

That distance translates to the chill realm of the giant gaseous planets where sunlight is weak and ice is common. Try stretching your imagination that evening to sense as best you can the vast gulf between the two worlds.

You might also try taking a picture of them with your mobile phone. I suggest this because the sky will be light enough to get a hand-held photo of the scene. Photos or not, don’t miss what the planets have in store for earthlings this week.