Beneath the Surface: Seeing Jupiter’s Hidden Storms


Launched on August 5, 2011, NASA’s Juno spacecraft will arrive at Jupiter in 2016 to study its magnetic field and atmosphere. Using its suite of science instruments Juno will peer inside the gas giant’s thick clouds, revealing hidden structures and powerful storms. To help people visualize what it means to see the invisible, JPL’s visual strategist Dan Goods created the exhibit above, titled Beneath the Surface. It’s an installation of lights, sound and fog effects that dramatically recreates what Juno will experience as it orbits Jupiter. By using their cell phone cameras, viewers can see lightning “storms” hidden beneath upper, opaque layers of “atmosphere”… in much the same way Juno will.

Goods explains: “Humans are only able to see a little, tiny sliver of what there is available in light. There’s gamma rays, microwaves, ultraviolet and infrared light also, and infrared is close enough to the visible part of the spectrum that cell phone cameras can pick it up. Cell phones normally produce more grainy photos at night because they don’t try to cut out the infrared light the way higher-end digital cameras do so in this case, the cell phone cameras are an advantage.” (Via the Pasadena Weekly.)

I had a chance to meet Dan Goods during a Tweetup event for the Juno launch at Kennedy Space Center. He’d brought a table that had magnetic elements set beneath a flat black surface, and by passing a handheld magnet over the table you could “detect” the different magnetic fields… in some cases rather strongly, even though they were all obviously invisible. It was an ingenious way that Juno’s abilities could be demonstrated in a “hands-on” manner.

Watch my video of the Juno launch from the KSC press site.

[/caption]

Beneath the Surface takes that kind of demonstration to an entirely new level.

“I love to work with the world of things that are right in front of you but you just can’t see,” Goods said. “With Juno, there’s all this structure just under the surface of Jupiter, but humans can develop tools that help us understand things we’d never have seen before.”

The exhibit was installed at the Pasadena Museum of California Art until January 8. It will now travel to science museums around the country.

Video: watch how the exhibit was constructed.

Juno’s primary goal is to improve our understanding of Jupiter’s formation and evolution. The spacecraft will spend a year investigating the planet’s origins, interior structure, deep atmosphere and magnetosphere. Juno’s study of Jupiter will help us to understand the history of our own solar system and provide new insight into how planetary systems form and develop in our galaxy and beyond.

Explore the Juno mission more at http://missionjuno.swri.edu/.

“Pluto-Killer” Sets Sights on Neptune

[/caption]

The confessed (and remorseless) “Pluto Killer” Mike Brown has turned his gaze – and the 10-meter telescope at the Keck Observatory in Hawaii – on Neptune, our solar system’s furthest “official” planet. But no worries for Neptune – Mike isn’t after its planetary status… he’s taken some beautiful infrared images instead!

Normally only visible as a featureless blue speck in telescopes, Brown’s image of Neptune — along with its largest moon Triton —  shows the icy gas giant in infrared light, glowing bright red and orange.

Neptune and Triton in infrared. Credit: Mike Brown/CalTech.

Brown’s initial intention was not just to get some pretty pictures of planets. The target of the imaging mission was Triton and to learn more about the placement of its methane, nitrogen and seasonal frosts, and this sort of research required infrared imaging. Of course, Neptune turned out to be quite photogenic itself.

“The big difference is doing the imaging in the infrared where methane absorbs most of the photons,” said Brown. “So the bright places are high clouds where the sunlight reflects off of them before it had a chance to pass through much of the atmosphere. Dark is clear atmosphere full of methane absorption.

“I just thought it was so spectacular that I should post it.”

No argument here, Mike!

Neptune, now officially the outermost planet in our solar system, is the fourth largest planet and boasts the highest wind speeds yet discovered — 1,250 mph winds scream around its frigid skies! Like the other gas giants Neptune has a system of rings, although nowhere near as extravagant as Saturn’s. It has 13 known moons, of which Triton is the largest.

With its retrograde orbit, Triton is believed to be a captured Kuiper Belt Object now in orbit around Neptune. Kuiper Belt Objects are Mike Brown’s specialty, as he is the astronomer most well-known for beginning the whole process that got Pluto demoted from the official planet list back in 2006.

Read more on Skymania.com here.

_______________

Jason Major is a graphic designer, photo enthusiast and space blogger. Visit his website Lights in the Dark and follow him on Twitter @JPMajor or on Facebook for the most up-to-date astronomy awesomeness!

Studying Saturn’s Super Storm

[/caption]

First seen by amateur astronomers back in December, the powerful seasonal storm that has since bloomed into a planet-wrapping swath of churning clouds has gotten some scrutiny by Cassini and the European Southern Observatory’s Very Large Telescope array situated high in the Chilean desert.

The image above shows three views of Saturn acquired on January 19: one by amateur astronomer Trevor Barry taken in visible light and the next two by the VLT’s infrared VISIR instrument – one taken in wavelengths sensitive to lower atmospheric structures one sensitive to higher-altitude features. 

Cassini image showing dredged-up ammonia crystals in the storm. NASA/JPL/Univ. of Arizona.

While the storm band can be clearly distinguished in the visible-light image, it’s the infrared images that really intrigue scientists. Bright areas can be seen along the path of the storm, especially in the higher-altitude image, marking large areas of upwelling warmer air that have risen from deep within Saturn’s atmosphere.

Normally relatively stable, Saturn’s atmosphere exhibits powerful storms like this only when moving into its warmer summer season about every 29 years. This is only the sixth such storm documented since 1876, and the first to be studied both in thermal infrared and by orbiting spacecraft.

The initial vortex of the storm was about 5,000 km (3,000 miles) wide and took researchers and astronomers by surprise with its strength, size and scale.

“This disturbance in the northern hemisphere of Saturn has created a gigantic, violent and complex eruption of bright cloud material, which has spread to encircle the entire planet… nothing on Earth comes close to this powerful storm.”

– Leigh Fletcher, lead author and Cassini team scientist at the University of Oxford in the United Kingdom.

The origins of Saturn’s storm may be similar to those of a thunderstorm here on Earth; warm, moist air rises into the cooler atmosphere as a convective plume, generating thick clouds and turbulent winds. On Saturn this mass of warmer air punched through the stratosphere, interacting with the circulating winds and creating temperature variations that further affect atmospheric movement.

The temperature variations show up in the infrared images as bright “stratospheric beacons”. Such features have never been seen before, so researchers are not yet sure if they are commonly found in these kinds of seasonal storms.

“We were lucky to have an observing run scheduled for early in 2011, which ESO allowed us to bring forward so that we could observe the storm as soon as possible. It was another stroke of luck that Cassini’s CIRS instrument could also observe the storm at the same time, so we had imaging from VLT and spectroscopy of Cassini to compare. We are continuing to observe this once-in-a-generation event.”

– Leigh Fletcher

A separate analysis using Cassini’s visual and infrared mapping spectrometer confirmed the storm is very violent, dredging up larger atmospheric particles and churning up ammonia from deep in the atmosphere. Other Cassini scientists are studying the evolving storm and a more extensive picture will emerge soon.

Read the NASA article here, or the news release from ESO here.

 

The leading edge of Saturn's storm in visible RGB color from Cassini raw image data taken on February 25, 2011. (The scale size of Earth is at upper left.) NASA / JPL / Space Science Institute. Edited by J. Major.

WISE Mission Completes All-sky Infrared Survey

[/caption]

If you take a lot of digital pictures, you’re probably familiar with the frustration of keeping track of dozens of files, and always running out of hard drive space to store them. Well, the scientists and engineers on NASA’s Wide-field Infrared Survey Explorer (WISE) mission have no pity for you. Their spacecraft just finished photographing the entire sky in exquisite detail: a total of 1.3 million photos.

“The eyes of WISE have not blinked since launch,” said William Irace, the mission’s project manager at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “Both our telescope and spacecraft have performed flawlessly and have imaged every corner of our universe, just as we planned.”

WISE surveys the sky in strips as it orbits the earth. It takes six months of constant observing to map the entire sky. By pointing at every part of the sky, astronomical surveys deliver excellent data covering both well-known objects and those that have never been seen before.

“WISE is filling in the blanks on the infrared properties of everything in the universe from nearby asteroids to distant quasars,” said Peter Eisenhardt of JPL, project scientist for WISE. “But the most exciting discoveries may well be objects we haven’t yet imagined exist.”

One example of a well-known object seen in new light by WISE is the Pleiades cluster: a group of young blue stars shrouded by dust that the cluster is currently passing through. In WISE’s false-color infrared vision, the hot stars look blue but the cooler dust clouds give off longer wavelengths of infrared light, causing them to glow in shades of yellow and green.

The WISE survey is particularly significant because such a wide range of objects in the universe are visible in infrared light. Giant molecular clouds glow in infrared light, as do brown dwarfs – objects that are bigger than planets but smaller than true stars. WISE can also see ultra-bright, extremely distant galaxies whose visible light has been stretched into the infrared by the expansion of the universe during its multi-billion-year journey.

The recently completed WISE survey also observed 100,000 asteroids in our solar system, many of which had never been seen before. 90 of the newly discovered asteroids are near-earth objects, whose orbits cross our own, making them potentially dangerous but also potential targets for future mission.

You might think that 1.3 million pictures would be plenty, but WISE will keep mapping the sky for another three months, covering half of the sky again and allowing astronomers to search for changes. The mission will end when the spacecraft’s solid hydrogen coolant finally runs out and the infrared detectors warm up (they don’t work as well when they are warm enough to emit the same wavelengths of infrared light that they are meant to detect).

But even as the telescope warms up, the astronomers on the WISE team will just be getting warmed up too. With nearly two million images, they will be busy making new discoveries for years to come.

Radiation from the Sun

Extreme Ultraviolet Sun

[/caption]Radiation from the Sun, which is more popularly known as sunlight, is a mixture of electromagnetic waves ranging from infrared (IR) to ultraviolet rays (UV). It of course includes visible light, which is in between IR and UV in the electromagnetic spectrum.

All electromagnetic waves (EM) travel at a speed of approximately 3.0 x 10 8 m/s in vacuum. Although space is not a perfect vacuum, as it is really composed of low-density particles, EM waves, neutrinos, and magnetic fields, it can certainly be approximated as such.

Now, since the average distance between the Earth and the Sun over one Earth orbit is one AU (about 150,000,000,000 m), then it will take about 8 minutes for radiation from the Sun to get to Earth.

Actually, the Sun does not only produce IR, visible light, and UV. Fusion in the core actually gives off high energy gamma rays. However, as the gamma ray photons make their arduous journey to the surface of the Sun, they are continuously absorbed by the solar plasma and re-emitted to lower frequencies. By the time they get to the surface, their frequencies are mostly only within the IR/visible light/UV spectrum.

During solar flares, the Sun also emits X-rays. X-ray radiation from the Sun was first observed by T. Burnight during a V-2 rocket flight. This was later confirmed by Japan’s Yohkoh, a satellite launched in 1991.

When electromagnetic radiation from the Sun strikes the Earth’s atmosphere, some of it is absorbed while the rest proceed to the Earth’s surface. In particular, UV is absorbed by the ozone layer and re-emitted as heat, eventually heating up the stratosphere. Some of this heat is re-radiated to outer space while some is sent to the Earth’s surface.

In the meantime, the electromagnetic radiation that wasn’t absorbed by the atmosphere proceeds to the Earth’s surface and heats it up. Some of this heat stays there while the rest is re-emitted. Upon reaching the atmosphere, part of it gets absorbed and part of it passes through. Naturally, the ones that get absorbed add to the heat already there.

The presence of greenhouse gases make the atmosphere absorb more heat, reducing the fraction of outbound EM waves that pass through. Known as the greenhouse effect, this is the reason why heat can build up some more.

The Earth is not the only planet that experiences the greenhouse effect. Read about the greenhouse effect taking place in Venus here in Universe Today. We’ve also got an interesting article that talks about a real greenhouse on the Moon by 2014.

Here’s a simplified explanation of the greenhouse effect on the EPA’s website. There’s also NASA’s Climate Change page.

Relax and listen to some interesting episodes at Astronomy Cast. Want to know more aboutUltraviolet Astronomy? How different is it from Optical Astronomy?

References:
NASA Science: The Electromagnetic Spectrum
NASA Earth Observatory

Infrared Spectroscopy

[/caption]
Infrared spectroscopy is spectroscopy in the infrared (IR) region of the electromagnetic spectrum. It is a vital part of infrared astronomy, just as it is in visual, or optical, astronomy (and has been since lines were discovered in the spectrum of the Sun, in 1802, though it was a couple of decades before Fraunhofer began to study them systematically).

For the most part, the techniques used in IR spectroscopy, in astronomy, are the same or very similar to those used in the visual waveband; confusingly, then, IR spectroscopy is part of both infrared astronomy and optical astronomy! These techniques involve use of mirrors, lenses, dispersive media such as prisms or gratings, and ‘quantum’ detectors (silicon-based CCDs in the visual waveband, HgCdTe – or InSb or PbSe – arrays in IR); at the long-wavelength end – where the IR overlaps with the submillimeter or terahertz region – there are somewhat different techniques.

As infrared astronomy has a much longer ground-based history than a space-based one, the terms used relate to the windows in the Earth’s atmosphere where lower absorption spectroscopy makes astronomy feasible … so there is the near-IR (NIR), from the end of the visual (~0.7 &#181m) to ~3 &#181m, the mid (to ~30 &#181m), and the far-IR (FIR, to 0.2 mm).

As with spectroscopy in the visual and UV wavebands, IR spectroscopy in astronomy involves detection of both absorption (mostly) and emission (rather less common) lines due to atomic transitions (the hydrogen Paschen, Brackett, Pfund, and Humphreys series are all in the IR, mostly NIR). However, lines and bands due to molecules are found in the spectra of nearly all objects, across the entire IR … and the reason why space-based observatories are needed to study water and carbon dioxide (to take just two examples) in astronomical objects. One of the most important class of molecules (of interest to astronomers) is PAHs – polycyclic aromatic hydrocarbons – whose transitions are most prominent in the mid-IR (see the Spitzer webpage Understanding Polycyclic Aromatic Hydrocarbons for more details).

Looking for more info on how astronomers do IR spectroscopy? Caltech has a brief introduction to IR spectroscopy. The ESO’s Very Large Telescope (VLT) has several dedicated instruments, including VISIR (which is both an imager and spectrometer, working in the mid-IR); CIRPASS, a NIR integrated field unit spectrograph on Gemini; Spitzer’s IRS (a mid-IR spectrograph); and LWS on the ESA’s Infrared Space Observatory (a FIR spectrometer).

Universe Today stories related to IR spectroscopy include Infrared Sensor Could Be Useful on Earth Too, Search for Origins Programs Shortlisted, and Jovian Moon Was Probably Captured.

Infrared spectroscopy is covered in the Astronomy Cast episode Infrared Astronomy.

Sources:
http://en.wikipedia.org/wiki/Infrared_spectroscopy
http://www2.chemistry.msu.edu/faculty/reusch/VirtTxtJml/Spectrpy/InfraRed/infrared.htm
http://www.chem.ucla.edu/~webspectra/irintro.html