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July 26, 2018 by Matt Williams

Underground Liquid Water Found on Mars!

Mars’ south polar ice cap. Credit: ESA / DLR / FU Berlin /

According to evidence gathered by multiple robotic orbiters, rovers, and landers over the course of several decades, scientists understand that Mars was once a warmer, watery place. But between 4.2 and 3.7 billion years ago, this began to change. As Mars magnetic field disappeared, the atmosphere slowly began to be stripped away by solar wind, leaving the surface the cold and dry and making it impossible for water to exist in liquid form.

While much of the planet’s water is now concentrated in the polar ice caps, scientists have speculated some of Mars’ past water could still be located underground. Thanks to a new study by a team of Italian scientists, it has now been confirmed that liquid water still exists beneath Mars’ southern polar region. This discovery has put an end to a fifteen-year mystery and bolstered the potential for future missions to Mars.

The study, titled “Radar evidence of subglacial liquid water on Mars“, recently appeared in the journal Science. The study was led by Roberto Orosei of the National Institute of Astrophysics (INAF) in Italy, and included members from the Italian Space Agency (ASI), the ESA Center for Earth Observation (ESRIN), and multiple observatories, research institutions and universities.

*Radar detection of water under the south pole of Mars. Credit: ESA/NASA/JPL/ASI/Univ. Rome*

So far, robotic missions have revealed considerable evidence of past water on Mars. These include dried-out river valleys and gigantic outflow channels discovered by orbiters, and evidence of mineral-rich soils that can only form in the presence of liquid water by rovers and landers. Early evidence from the ESA’s Mars Express probe has also showed that water-ice exists at the planet’s poles and is buried in the layers interspersed with dust.

However, scientists have long suspected that liquid water could exist beneath the polar ice caps, much in the same way that liquid water is believed to underlie glaciers here on Earth. In addition, the presence of salts on Mars could further reduce the melting point of subsurface water and keep it in a liquid state, despite the sub-zero temperatures present on both the surface and underground.

For many years, data from the Mars Express’ Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) instrument – which has been used to study the southern polar region – has remained inconclusive. Like all ground-penetrating radar, this instrument relies on radar pulses to map surface topography and determine the properties of the materials that lie beneath the surface.

Luckily, after considerable analysis, the study team was able to develop new techniques that allowed them to collect enough high-resolution data to confirm the presence of liquid water beneath the southern ice cap. As Andrea Cicchetti, the MARSIS operations manager and a co-author on the new paper, indicated:

“We’d seen hints of interesting subsurface features for years but we couldn’t reproduce the result from orbit to orbit, because the sampling rates and resolution of our data was previously too low. We had to come up with a new operating mode to bypass some onboard processing and trigger a higher sampling rate and thus improve the resolution of the footprint of our dataset: now we see things that simply were not possible before.”

Water detection under the south pole of Mars. Credit: Context map: NASA/Viking; THEMIS background: NASA/JPL-Caltech/Arizona State University; MARSIS data: ESA/NASA/JPL/ASI/Univ. Rome; R. Orosei et al 2018

What they found was that the southern polar region is made of many layers of ice and dust down to a depth of about 1.5 km over a 200 km-wide area, and featured an anomalous area measuring 20-km wide. As Roberto Orosei, the principal investigator of the MARSIS experiment and lead author of the paper, explained in a recent ESA press release:

“This subsurface anomaly on Mars has radar properties matching water or water-rich sediments. This is just one small study area; it is an exciting prospect to think there could be more of these underground pockets of water elsewhere, yet to be discovered.”

After analyzing the properties of the reflected radar signals and taking into account the composition of the layered deposits and expected temperature profiles below the surface, the scientists concluded that the 20-km wide feature is an interface between the ice and a stable body of liquid water. For MARSIS to be able to detect such a patch of water, it would need to be at least several tens of centimeters thick.

These findings also raise the possibility of there being life on Mars, both now and in the past. This is based on research that found microbial life in Lake Vostok, which is located some 4 km (2.5 mi) below the ice in Antarctica. If life can thrive in salty, subglacial environments on Earth, then it is possible that they could survive on Mars as well. Determining if this is the case will be the purpose of existing and future missions to Mars.

*The MARSIS instrument on the Mars Express is a ground penetrating radar sounder used to look for subsurface water and ice. Credit: ESA*

As Dmitri Titov, one of the Mars Express project scientist, explained:

“The long duration of Mars Express, and the exhausting effort made by the radar team to overcome many analytical challenges, enabled this much-awaited result, demonstrating that the mission and its payload still have a great science potential. This thrilling discovery is a highlight for planetary science and will contribute to our understanding of the evolution of Mars, the history of water on our neighbour planet and its habitability.”

The Mars Express launched on June 2nd, 2003, and will celebrate 15 years in orbit of Mars by December 25th this year. In the coming years, it will be joined by the ESA’s ExoMars 2020 mission, NASA’s Mars 2020 Rover, and a number of other scientific experiments. These missions will pave the way for a potential crewed mission, which NASA is planning to mount by the 2030s.

If there is indeed liquid water to be found on Mars, it will go a long way towards facilitating future research and even an ongoing human presence on the surface. And if there is still life on Mars, the careful research of its ecosystems will help address the all-important question of how and when life emerged in the Solar System.

Further Reading: ESA, Science

July 25, 2018July 25, 2018 by Matt Williams

Andromeda Shredded and Consumed a Massive Galaxy About Two Billion Years Ago

Andromeda Galaxy. Credit: Wikipedia Commons/Adam Evans

Scientists have long understood that in the course of cosmic evolution, galaxies become larger by consuming smaller galaxies. The evidence of this can be seen by observing galactic halos, where the stars of cannibalized galaxies still remain. This is certainly true of the Andromeda Galaxy (aka. M31, Earth’s closest neighbor) which has a massive and nearly-invisible halo of stars that is larger than the galaxy itself.

For some time, scientists believed that this halo was the result of hundreds of smaller mergers. But thanks to a new study by a team of researchers at the University of Michigan, it now appears that Andromeda’s halo is the result of it cannibalizing a massive galaxy some two billion years ago. Studying the remains of this galaxy will help astronomers understand how disk galaxies (like the Milky Way) evolve and survive large mergers.

The study, titled “The Andromeda galaxy’s most important merger about 2 billion years ago as M32’s likely progenitor“, recently appeared in the scientific journal Nature. The study was conducted by Richard D’Souza, a postdoctoral researcher at the University of Michigan and the Vatican Observatory; and Eric F. Bell, the Arthur F. Thurnau Professor at the University of Michigan.

*In this image, the Andromeda galaxy shreds the large galaxy M32p, which eventually resulted in M32 and a giant halo of stars. Credit: Richard D’Souza. Credit: AAS/IOP/Wei-Hao Wang*

Using computer models, Richard D’Souza and Eric Bell were able to piece together how a once-massive galaxy (named M32p) disrupted and eventually came to merge with Andromeda. From their simulations, they determined that M32p was at least 20 times larger than any galaxy that has merged with the Milky Way over the course of its lifetime.

M32p would have therefore been the third-largest member of the Local Group of galaxies, after the Milky Way and Andromeda galaxies, and was therefore something of a “long-lost sibling”. However, their simulations also indicated that many smaller companion galaxies merged with Andromeda over time. But for the past, Andromeda’s halo is the result of a single massive merger. As D’Souza explained in a recent Michigan News press statement:

“It was a ‘eureka’ moment. We realized we could use this information of Andromeda’s outer stellar halo to infer the properties of the largest of these shredded galaxies. Astronomers have been studying the Local Group—the Milky Way, Andromeda and their companions—for so long. It was shocking to realize that the Milky Way had a large sibling, and we never knew about it.”

This study will not only help astronomers understand how galaxies like the Milky Way and Andromeda grew through mergers, it might also shed light on a long-standing mystery – which is how Andromeda’s satellite galaxy (M32) formed. According to their study, D’Souza and Bell believe that M32 is the surviving center of M32p, which is what remained after its spiral arms were stripped away.

*Messier 31 (the Andromeda Galaxy), along with Messier 32 and Messier 110. Credit: Wikisky*

“M32 is a weirdo,” said Bell. “While it looks like a compact example of an old, elliptical galaxy, it actually has lots of young stars. It’s one of the most compact galaxies in the universe. There isn’t another galaxy like it.” According to D’Souza and Bell, this study may also alter the traditional understanding of how galaxies evolve. In astronomy, conventional wisdom says that large interactions would destroy disk galaxies and form elliptical galaxies.

But if Andromeda did indeed survive an impact with a massive galaxy, it would indicate that this is not the case. The timing of the merger may also explain recent research findings which indicated that two billion years ago, the disk of the Andromeda galaxy thickened, leading to a burst in star formation. As Bell explained:

“The Andromeda Galaxy, with a spectacular burst of star formation, would have looked so different 2 billion years ago. When I was at graduate school, I was told that understanding how the Andromeda Galaxy and its satellite galaxy M32 formed would go a long way towards unraveling the mysteries of galaxy formation.”

In the end, this method could also be used to study other galaxies and determine which were the most massive mergers they underwent. This could allow scientists to better understand the complicated process that drives galaxy growth and how mergers affect galaxies. This knowledge will certainly come in handy when it comes to determining what will happen to our galaxy when it merges with Andromeda in a few billion years.

Further Reading: Michigan News

July 25, 2018July 26, 2018 by David Dickinson

Mars Meets the MiniMoon During the Longest Total Lunar Eclipse of the Century

The Blood Moon cometh.

One of the top astronomy events of 2018 occurs on the evening of Friday, July 27^th, when the Moon enters the shadow of the Earth for a total lunar eclipse. In the vernacular that is the modern internet, this is what’s becoming popularly known as a “Blood Moon,” a time when the Moon reddens due to the refracted sunlight from a thousand sunsets falling upon it. Standing on the surface of the Moon during a total lunar eclipse (which no human has yet to do) you would see a red “ring of fire” ’round the limb of the eclipsed Earth.

This is the second total lunar eclipse for 2018, and the middle of a unique eclipse season bracketed by two partial solar eclipses, one on July 13^th, and another crossing the Arctic and Scandinavia on August 11^th.

The path of the Moon through the Earth’s shadow Friday, along with visibility prospects worldwide. Credit: NASA/GSFC

The July 27^th total lunar eclipse technically begins around 17:15 Universal Time (UT), when the Moon enters the bright penumbral edge of the Earth’s shadow. Expect the see a slight shading on the southwest edge of the Moon’s limb about 30 minutes later. The real action begins around 18:24 UT, when the Moon starts to enter the dark inner umbra and the partial phases of the eclipse begin. Totality runs from 19:30 UT to 21:13 UT, and the cycle reverses through partial and penumbral phases, until the eclipse ends at 23:29 UT.

Centered over the Indian Ocean region, Africa, Europe and western Asia get a good front row seat to the entire total lunar eclipse. Australia and eastern Asia see the eclipse in progress at moonset, and South America sees the eclipse in progress at moonrise just after sunset. Only North America sits this one out.

Now, this total lunar eclipse is special for a few reasons.

First off, we’ll have the planet Mars at opposition less than 15 hours prior to the eclipse. This means the Red Planet will shine at a brilliant magnitude -2.8, just eight degrees from the crimson Moon during the eclipse, a true treat and an easy crop to get both in frame. We fully expect to see some great images of Mars at opposition along with the eclipsed Moon.

Mars versus the eclipsed Moon on Friday. Credit: Stellarium

How close can the two get? Well, stick around until April 27^th, 2078 and you can see the Moon occult (pass in front of) Mars during a penumbral lunar eclipse as seen from South America.

And speaking of occultations, the Moon occults some interesting stars during totality Friday, the brightest of which is the +5.9 magnitude double star Omicron Capricorni (SAO 163626) as seen from Madagascar and the southern tip of Africa. Omicron Capricorni has a wide separation of 22″.

The occultation path of Omicron Capricorni during Friday’s eclipse. Credit: Occult 4.2.

The second unique fact surrounding this eclipse is one you’ve most likely already heard: it is indeed the longest one for this century… barely. This occurs because the Moon reaches its descending node along the ecliptic on July 27^that 22:40 UT, just 21 minutes after leaving the umbral shadow of the Earth. This makes for a very central eclipse, nearly piercing the umbral shadow of the Earth right through its center.

Totality on Friday lasts for 1 hour, 42 minutes and 57 seconds. This was last beat on July 16^th, 2000 with a duration of 1 hour, 46 minutes and 24 seconds (2001 is technically the first year of the 21^st century). The duration for Friday’s eclipse won’t be topped until June 9^th 2123 (1 hour 46 minutes six seconds), making it the longest for a 123 year span.

The longest total lunar eclipse over the span of 5,000 years from 2000 BC to 3000 AD was on May 31^st, 318 AD at 106.6 minutes in duration.

A Minimoon Eclipse

Finally, a third factor is assisting this eclipse in its longevity is the onset of the MiniMoon: The Moon reaches apogee at July 27^th, 5:22 UT, 14 hours and 37 minutes prior to Full and the central time of the eclipse. This is the most distant Full Moon of the year for 2018 (406,222 km at apogee) the 2^nd most distant apogee for 2018. Apogee on January 15^th, beats it out by only 237 kilometers. This not only gives the Moon a slightly smaller size visually at 29.3′, versus 34.1′ near perigee, less than half of the 76′ arcminute diameter of the Earth’s shadow. This also means that the Moon is moving slightly slower in its orbit, making a more stately pass through the Earth’s shadow.

Going, going… the stages of a lunar eclipse. Credit: Dave Dickinson.

What will the Moon look like during the eclipse? Not all total lunar eclipses are the same, but I’d expect a dark, brick red hue from such a deep eclipse. The color of the Moon during a eclipse is described as its Danjon number, ranging from a bright (4) to dark murky copper color (0) during totality.

Tales of the Saros

This particular eclipse is member 38 of the 71 lunar eclipses in saros series 129, running from June 10^th, 1351 all the way out to the final eclipse in the series on July 24^th, 2613 AD. If you caught the super-long July 16^th, 2000 eclipse (the longest for the 20th century) then you saw the last one in the series, and the next one for the series occurs on August 7^th, 2036. Collect all three, and you’ve completed a triple exeligmos series, a fine word in Scrabble to land on a triple word score.

Photographing the Moon

If you can shoot the Moon, you can shoot a total lunar eclipse, though a minimum focal length lens of around 200mm is needed to produce a Moon much larger that a dot. The key moment is the onset of totality, when you need to be ready to rapidly dial the exposure settings down from the 1/100^th of a second range down to 1 second or longer. Be careful not to lose sight of the Moon in the viewfinder all together!

Are you watching the eclipse during moonrise or moonset? This is a great time to shoot the eclipsed Moon along with foreground objects… you can also make an interesting observation around this time, and nab the eclipsed Moon and the Sun above the local horizon at the same time in what’s termed a selenelion. This works mainly because the Earth’s shadow is larger than the apparent diameter of the Moon, allowing it to be cast slightly off to true center after sunrise or just before sunset. Gaining a bit of altitude and having a low, flat horizon helps, as the slight curve of the Earth also gives the Sun and Moon a tiny boost. For this eclipse, the U2-U3 umbral contact zone for a selenelion favors eastern Brazil, the UK and Scandinavia at moonrise, and eastern Australia, Japan and northeastern China at moonset.

Incidentally, a selenelion is the second visual proof you see during a lunar eclipse that the Earth is indeed round, the first being the curve of the planet’s shadow seen at all angles as it falls across the Moon.

Another interesting challenge would be to capture a transit of the International Space Station during the eclipse, either during the partial or total phases… to our knowledge, this has never been done during a lunar eclipse. This Friday, South America gets the best shots at a lunar eclipse transit of the ISS:

ISS transit paths (revised) during Friday’s eclipse, including times in UT and Moon phases. The northern and southern limits of the paths mark the point where the Moon is no longer visible. Created by the author using CalSky. (Thanks to PAHLES in comments below for pointing out the errors in the first map!)

Be sure to check CalSky for a transit near you.

Watch Friday’s eclipse live online. Credit: Gianluca Masi/Virtual Telescope Project.

Live on the wrong continent, or simply have cloudy skies? Gianluca Masi and the Virtual Telescope Project 2.0 have you covered, with a live webcast of the eclipse from the heart of Rome, Italy on July 27^th starting at 18:30 UT.

Be sure to catch Friday’s total lunar eclipse, either in person or online… we won’t have another one until January 21^st, 2019.

Learn about eclipses, occultations, the motion of the Moon and more in our new book: Universe Today’s Guide to the Cosmos: Everything You Need to Know to Become an Amateur Astronomer now available for pre-order.

July 24, 2018July 25, 2018 by Matt Williams

Life on Europa Would be Protected by Just a Few Centimeters of Ice

Radiation from Jupiter can destroy molecules on Europa's surface. Material from Europa's ocean that ends up on the surface will be bombarded by radiation, possibly destroying any biosignatures, or chemical signs that could imply the presence of life. Credit: NASA/JPL-Caltech

Ever since the Galileo probe provided compelling evidence for the existence of a global ocean beneath the surface of Europa in the 1990s, scientists have wondered when we might be able to send another mission to this icy moon and search for possible signs of life. Most of these mission concepts call for an orbiter or lander than will study Europa’s surface, searching the icy sheet for signs of biosignatures turned up from the interior.

Unfortunately, Europa’s surface is constantly bombarded by radiation, which could alter or destroy material transported to the surface. Using data from the Galileo and Voyager 1 spacecraft, a team of scientists recently produced a map that shows how radiation varies across Europa’s surface. By following this map, future missions like NASA’s Europa Clipper will be able to find the spots where biosignatures are most likely to still exist.

As many missions have revealed by studying Europa’s surface, the moon experiences periodic exchanges between the interior and the surface. If there is life in its interior ocean, then biological material could theoretically be brought to the surface where it could be studied. Since radiation from Jupiter’s magnetic field would destroy this material, knowing where it is most intense, how deep it goes, and how it could affect the interior are all important questions.

*Artist’s impression of water bubbling up from Europa’s interior ocean and breaching the surface ice. Credit: NASA/JPL-Caltech*

As Tom Nordheim, a research scientist at NASA’s Jet Propulsion Laboratory, explained in a recent NASA press release:

“If we want to understand what’s going on at the surface of Europa and how that links to the ocean underneath, we need to understand the radiation. When we examine materials that have come up from the subsurface, what are we looking at? Does this tell us what is in the ocean, or is this what happened to the materials after they have been radiated?”

To address these question, Nordheim and his colleagues examined data from Galileo‘s flybys of Europa and electron measurements from NASA’s Voyager 1 spacecraft. After looking closely at the electrons blasting the moon’s surface, Nordheim and his team found that the radiation doses vary by location. The harshest radiation is concentrated in zones around the equator, and the radiation lessens closer to the poles.

The study which describes their findings recently appeared in the scientific journal Nature under the title “Preservation of potential biosignatures in the shallow subsurface of Europa“. The study was led by Nordheim and was co-authored by Kevin Hand (also with the JPL) and Chris Paranicas from the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland.

Artist’s concept of a Europa Clipper mission. Credit: NASA/JPL

“This is the first prediction of radiation levels at each point on Europa’s surface and is important information for future Europa missions,” said Paranicas. Now that scientists know where to find regions least altered by radiation, they will be able to designate areas of study for the Europa Clipper, a JPL-led mission that is expected to launch as early as 2022.

For the sake of their study, Nordheim and his team went beyond a conventional two-dimensional map to build 3D models that examined how far below the surface the radiation penetrates. To test how deep organic material would have to be buried in order to survive, Nordheim and his team tested the effect of radiation on amino acids (the basic building blocks for proteins) to figure out how Europa’s exposure to radiation would affect potential biosignatures.

The results indicate how deep scientists will need to dig or drill during a potential future Europa lander mission in order to find any biosignatures that might be preserved. In the highest-radiation zones around the equator, the depth at which biosignatures could be found ranged from 10 to 20 cm (4 to 8 inches). At the middle- and high-latitudes, closer to the poles, the depths decrease to about 1 cm (0.4 inches). As Hand indicated:

“The radiation that bombards Europa’s surface leaves a fingerprint. If we know what that fingerprint looks like, we can better understand the nature of any organics and possible biosignatures that might be detected with future missions, be they spacecraft that fly by or land on Europa.”

*Artist’s impression of a water vapor plume on Europa. Credit: NASA/ESA/K. Retherford/SwRI*

When the Europa Clipper mission reaches the Jovian system, the spacecraft will orbit Jupiter and conducting about 45 close flybys of Europa. It’s advanced suite of scientific instruments will include cameras, spectrometers, plasma and radar instruments which will investigate the composition of the moon’s surface, its ocean, and material that has been ejected from the surface.

“Europa Clipper’s mission team is examining possible orbit paths, and proposed routes pass over many regions of Europa that experience lower levels of radiation,” Hand said. “That’s good news for looking at potentially fresh ocean material that has not been heavily modified by the fingerprint of radiation.”

With this new radiation map, the mission team will be able to narrow the range of possible research sites. This, in turn, will increase the likelihood that the orbiter mission will be able to settle the decades-old mystery of whether or not there is life in the Jovian system.

Further Reading: NASA, Nature

July 23, 2018 by Matt Williams

This is a Photo of Neptune, From the Ground! ESO’s New Adaptive Optics Makes Ground Telescopes Ignore the Earth’s Atmosphere

This image of the planet Neptune was obtained during the testing of the Narrow-Field adaptive optics mode of the MUSE/GALACSI instrument on ESO’s Very Large Telescope. The corrected image is sharper than a comparable image from the NASA/ESA Hubble Space Telescope. Credit: ESO/P. Weilbacher (AIP)

In 2007, the European Southern Observatory (ESO) completed work on the Very Large Telescope (VLT) at the Paranal Observatory in northern Chile. This ground-based telescope is the world’s most advanced optical instrument, consisting of four Unit Telescopes with main mirrors (measuring 8.2 meters in diameter) and four movable 1.8-meter diameter Auxiliary Telescopes.

Recently, the VLT was upgraded with a new instrument known as the Multi Unit Spectroscopic Explorer (MUSE), a panoramic integral-field spectrograph that works at visible wavelengths. Thanks to the new adaptive optics mode that this allows for (known as laser tomography) the VLT was able to recently acquire some images of Neptune, star clusters and other astronomical objects with impeccable clarity.

In astronomy, adaptive optics refers to a technique where instruments are able to compensate for the blurring effect caused by Earth’s atmosphere, which is a serious issue when it comes to ground-based telescopes. Basically, as light passes through our atmosphere, it becomes distorted and causes distant objects to become blurred (which is why stars appear to twinkle when seen with the naked eye).

*Images of the planet Neptune obtained during the testing of the Narrow-Field adaptive optics mode of the MUSE/GALACSI instrument on ESO’s Very Large Telescope. Credit: ESO/P. Weilbacher (AIP*

One solution to this problem is to deploy telescopes into space, where atmospheric disturbance is not an issue. Another is to rely on advanced technology that can artificially correct for the distortions, thus resulting in much clearer images. One such technology is the MUSE instrument, which works with an adaptive optics unit called a GALACSI – a subsystem of the Adaptive Optics Facility (AOF).

The instrument allows for two adaptive optics modes – the Wide Field Mode and the Narrow Field Mode. Whereas the former corrects for the effects of atmospheric turbulence up to one km above the telescope over a comparatively wide field of view, the Narrow Field mode uses laser tomography to correct for almost all of the atmospheric turbulence above the telescope to create much sharper images, but over a smaller region of the sky.

This consists of four lasers that are fixed to the fourth Unit Telescope (UT4) beaming intense orange light into the sky, simulating sodium atoms high in the atmosphere and creating artificial “Laser Guide Stars”. Light from these artificial stars is then used to determine the turbulence in the atmosphere and calculate corrections, which are then sent to the deformable secondary mirror of the UT4 to correct for the distorted light.

Using this Narrow Field Mode, the VLT was able to capture remarkably sharp test images of the planet Neptune, distant star clusters (such as the globular star cluster NGC 6388), and other objects. In so doing, the VLT demonstrated that its UT4 mirror is able to reach the theoretical limit of image sharpness and is no longer limited by the effects of atmospheric distortion.

*The most powerful laser guide star system in the world sees first light at the Paranal Observatory. Credit: ESO*

This essentially means that it is now possible for the VLT to capture images from the ground that are sharper than those taken by the Hubble Space Telescope. The results from UT4 will also help engineers to make similar adaptations to the ESO’s Extremely Large Telescope (ELT), which will also rely on laser tomography to conduct its surveys and accomplish its scientific goals.

These goals include the study of supermassive black holes (SMBHs) at the centers of distant galaxies, jets from young stars, globular clusters, supernovae, the planets and moons of the Solar System, and extra-solar planets. In short, the use of adaptive optics – as tested and confirmed by the VLT’s MUSE – will allow astronomers to use ground-based telescopes to study the properties of astronomical objects in much greater detail than ever before.

In addition, other adaptive optics systems will benefit from work with the Adaptive Optics Facility (AOF) in the coming years. These include the ESO’s GRAAL, a ground layer adaptive optics module that is already being used by the Hawk-I infrared wide-field imager. In a few years, the powerful Enhanced Resolution Imager and Spectrograph (ERIS) instrument will also be added to the VLT.

Between these upgrades and the deployment of next-generation space telescopes in the coming years (like the James Webb Space Telescope, which will be deploying in 2021), astronomers expect to bringing a great deal more of the Universe “into focus”. And what they see is sure to help resolve some long-standing mysteries, and will probably create a whole lot more!

And be sure to enjoy these videos of the images obtained by the VLT of Neptune and NGC 6388, courtesy of the ESO:

Further Reading: ESO

July 22, 2018 by Matt Williams

This Stunning Photo Shows the Martian Dust Storm as it was Just Getting Going

True color image of a storm front located near Utopia Planitia, near the northern polar ice cap of Mars. Credit: Credits: ESA/DLR/FU Berlin

The weather patterns on Mars are rather fascinating, owing to their particular similarities and differences with those of Earth. For one, the Red Planet experiences dust storms that are not dissimilar to storms that happen regularly here on Earth. Due to the lower atmospheric pressure, these storms are much less powerful than hurricanes on Earth, but can grow so large that they cover half the planet.

Recently, the ESA’s Mars Express orbiter captured images of the towering cloud front of a dust storm located close to Mars’ northern polar region. This storm, which began in April 2018, took place in the region known as Utopia Planitia, close to the ice cap at the Martian North Pole. It is one of several that have been observed on Mars in recent months, one which is the most severe to take place in years.

The images (shown above and below) were created using data acquired by the Mars Express‘ High Resolution Stereo Camera (HRSC). The camera system is operated by the German Aerospace Center (DLR), and managed to capture images of this storm front – which would prove to be the harbinger of the Martian storm season – on April 3rd, 2018, during its 18,039th orbit of Mars.

*Anaglyph 3D image of the dust storm front forming above the subpolar plains in northern Mars. Credit: Credits: ESA/DLR/FU Berlin*

This storm was one of several small-scale dust storms that have been observered in recent months on Mars. A much larger storm emerged further southwest in the Arabia Terra region, which began in May of 2018 and developed into a planet-wide dust storm within several weeks.

Dust storms occur on Mars when the southern hemisphere experiences summer, which coincides with the planet being closer to the Sun in its elliptical orbit. Due to increased temperatures, dust particles are lifted higher into the atmosphere, creating more wind. The resulting wind kicks up yet more dust, creating a feedback loop that NASA scientists are still trying to understand.

Since the southern polar region is pointed towards the Sun in the summer, carbon dioxide frozen in the polar cap evaporates. This has the effect of thickening the atmosphere and increases surface pressure, which enhances the storms by helping to suspend dust particles in the air. Though they are common and can begin suddenly, Martian dust storms typically stay localized and last only a few weeks.

While local and regional dust storms are frequent, only a few of them develop into global phenomena. These storms only occur every three to four Martian years (the equivalent of approximately 6 to 8 Earth years) and can persist for several months. Such storms have been viewed many times in the past by missions like Mariner 9 (1971), Viking I (1971) and the Mars Global Surveyor (2001).

This global map of Mars shows a growing dust storm as of June 6, 2018. The map was produced by the Mars Color Imager (MARCI) camera on NASA’s Mars Reconnaissance Orbiter spacecraft. The blue dot indicates the approximate location of Opportunity. Image Credit: NASA/JPL-Caltech/MSSS

In 2007, a large storm covered the planet and darkened the skies over where the Opportunity rover was stationed – which led to two weeks of minimal operations and no communications. The most recent storm, which began back in May, has been less intense, but managed to create a state of perpetual night over Opportunity’s location in Perseverance Valley.

As a result, the Opportunity team placed the rover into hibernation mode and shut down communications in June 2018. Meanwhile, NASA’s Curiosity rover continues to explore the surface of Mars, thanks to its radioisotope thermoelectric generator (RTG), which does not rely on solar panels. By autumn, scientists expect the dust storm will weaken significantly, and are confident Opportunity will survive.

According to NASA, the dust storm will also not affect the landing of the InSight Lander, which is scheduled to take place on November 26th, 2018. In the meantime, this storm is being monitored by all five active ESA and NASA spacecraft around Mars, which includes the 2001 Mars Odyssey, the Mars Reconnaissance Orbiter, the Mars Atmosphere and Volatile EvolutioN (MAVEN), the Mars Express, and the Exomars Trace Gas Orbiter.

Understanding how global storms form and evolve on Mars will be critical for future solar-powered missions. It will also come in handy when crewed missions are conducted to the planet, not to mention space tourism and colonization!

Further Reading: DLR

July 20, 2018 by Matt Williams

Twelve New Moons Discovered Around Jupiter, and One of Them is Pretty Odd!

Illustration of Jupiter and the Galilean satellites. Credit: NASA

The gas giant Jupiter, which was named in honor of the king of the gods in the Roman pantheon, has always lived up to its name. In addition to being the largest planet in the Solar System – with two and a half times the mass of all the other planets combined – it also has an incredibly powerful magnetic field and the most intense storms of any planet in the Solar System.

What’s more, it is home to some of the largest moons in the Solar System (known as the Galilean Moons), and has more known moons than any other planet. And thanks to a recent survey led by Scott S. Sheppard of the Carnegie Institution of Science, twelve more moons have been discovered. This brings the total number of known moons around Jupiter to 79, and could provide new insight into the history of the Solar System.

The team was led by Scott S. Sheppard and included Dave Tholen (University of Hawaii) and Chad Trujillo (Northern Arizona University). It was this same team that first suggested the existence of a massive planet in the outer reaches of the Solar System (Planet 9 or Planet X) in 2014, based on the unusual behavior of certain populations of extreme Trans-Neptunian Objects (eTNOs).

*Artist’s impression of Jupiter’s moons, with the newly-discovered moons indicated in blue and red. Credit: Carnegie Institution of Science/Roberto Molar Candanosa*

Curiously enough, it was while Sheppard and his colleagues were hunting for this elusive planet that they spotted the first of these new moons in 2017. As Sheppard explained in a recent Carnegie press release:

“Jupiter just happened to be in the sky near the search fields where we were looking for extremely distant Solar System objects, so we were serendipitously able to look for new moons around Jupiter while at the same time looking for planets at the fringes of our Solar System.”

The initial discoveries were made using the Blanco 4-meter telescope at the Cerro Tololo Inter-American Observatory (CTIO) in Chile. They were then confirmed with the help of the Dark Energy Camera (DECam), which was added to the Blanco telescope as past of the Dark Energy Survey. Additional data was provided by the Carnegie Observatories 6.5-meter Magellan Telescopes.

The orbits of the newly-discovered moons were then calculated by Gareth Williams of the International Astronomical Union’s Minor Planet Center (MPC), based on the team’s observations. “It takes several observations to confirm an object actually orbits around Jupiter,” he said. “So, the whole process took a year.”

As you can see from the image above, two of the newly-discovered moons (indicated in blue) are part of the inner group that have prograde orbits (i.e. they orbit in the same direction as the planet’s rotation). They complete a single orbit in a little less than a year, and have similar orbital distances and angles of inclination. This is a possible indication that these moons are fragments of a larger moon that was broken apart, possibly due to a collision.

Nine of the new moons (indicated in red) are part of the distant outer group that have retrograde orbits, meaning they orbit in the opposite direction of Jupiter’s rotation. These moons take about two years to complete a single orbit of Jupiter and are grouped into three orbital groups that have similar distances and inclination. As such, they are also thought to be remnants of three larger moons that broke apart due to past collisions.

The team observed one other moon that does not fit into either group, and is unlike any known moon orbiting Jupiter. This “oddball moon” is more distant and more inclined than the prograde moons and takes about one and a half years to orbit Jupiter, which means its orbit crosses the outer retrograde moons. Because of this, head-on collisions are much more likely to occur with the retrograde moons, which are orbiting in the opposite direction.

The orbit of this oddball moon was also confirmed by Bob Jacobson and Marina Brozovic at NASA’s Jet Propulsion Laboratory in 2017. This was motivated in part to ensure that the moon would not be lost before it arrived at the predicted location in its orbit during the recovery observations made in 2018. As Sheppard explained,

“Our other discovery is a real oddball and has an orbit like no other known Jovian moon. It’s also likely Jupiter’s smallest known moon, being less than one kilometer in diameter…This is an unstable situation. Head-on collisions would quickly break apart and grind the objects down to dust.”

Caption: Recovery images of Valetudo from the Magellan telescope in May 2018. The moon can be seen moving relative to the steady state background of distant stars. Jupiter is not in the field but off to the upper left.

Here too, the team thinks that this moon could be the remains of a once-larger moon; in this case, one that had a prograde orbit that formed some of the retrograde moons through past collisions. The oddball moon already has a suggested name for it – Valetudo, after the Jupiter’s great-granddaughter, the goddess of health and hygiene in the Roman pantheon.

In addition to adding to Jupiter’s overall moon count, the study of what shaped these moon’s orbital histories could teach scientists a great deal about the earliest period of the Solar System. For instance, the fact that the smallest moons in Jupiter’s various orbital groups (prograde, retrograde) are still abundant suggests that the collisions that created them occurred after the era of planet formation.

According to the Nebular Hypothesis of Solar System formation, the Sun was still surrounded by a rotating protoplanetary disk at this time – i.e. the gas and dust from which the planets formed. Because of their sizes – 1 to 3 km – these moons would have been more influenced by surrounding gas and dust, which would have placed a drag on their orbits and caused them to fall inwards towards Jupiter.

The fact that these moons still exist shows that they likely formed after this gas and dust dissipated. In this respect, these moons are much like time capsules or geological records, preserving pieces of Jupiter’s (and the Solar Systems) history of formation and evolution.

This research was partially funded by a NASA Planetary Astronomy grant, and was made possible thanks to assistance by multiple observatories. These included the 4-meter Discovery Channel Telescope at Lowell Observatory Arizona, the 8-meter Subaru Telescope and the University of Hawaii’s 2.2 meter telescope, and the 8-meter Gemini Telescope in Hawaii.

Further Reading: Carnegie Institute of Science

July 18, 2018 by Matt Williams

NASA’s James Webb Space Telescope will Inspect the Atmospheres of Distant Gas Giants

Artist's impression of the Jupiter-size extrasolar planet, HD 189733b, being eclipsed by its parent star. Credits: ESA, NASA, M. Kornmesser (ESA/Hubble), and STScI

The James Webb Space Telescope is like the party of the century that keeps getting postponed. Due to its sheer complexity and some anomalous readings that were detected during vibration testing, the launch date of this telescope has been pushed back many times – it is currently expected to launch sometime in 2021. But for obvious reasons, NASA remains committed to seeing this mission through.

Once deployed, the JWST will be the most powerful space telescope in operation, and its advanced suite of instruments will reveal things about the Universe that have never before been seen. Among these are the atmospheres of extra-solar planets, which will initially consist of gas giants. In so doing, the JWST will refine the search for habitable planets, and eventually begin examining some potential candidates.

The JWST will be doing this in conjunction with the Transiting Exoplanet Survey Satellite (TESS), which deployed to space back in April of 2018. As the name suggests, TESS will be searching for planets using the Transit Method (aka. Transit Photometry), where stars are monitored for periodic dips in brightness – which are caused by a planet passing in front of them relative to the observer.

Artist Illustration of TESS and its 4 telescopes. Credit: NASA/MIT — *Artist concept of the Transiting Exoplanet Survey Satellite and its 4 telescopes. Credit: NASA/MIT*

Some of Webb’s first observations will be conducted through the Director’s Discretionary Early Release Science program – a transiting exoplanet planet team at Webb’s science operation center. This team is planning on conducting three different types of observations that will provide new scientific knowledge and a better understanding of Webb’s science instruments.

As Jacob Bean of the University of Chicago, a co-principal investigator on the transiting exoplanet project, explained in a NASA press release:

“We have two main goals. The first is to get transiting exoplanet datasets from Webb to the astronomical community as soon as possible. The second is to do some great science so that astronomers and the public can see how powerful this observatory is.”

As Natalie Batalha of NASA Ames Research Center, the project’s principal investigator, added:

“Our team’s goal is to provide critical knowledge and insights to the astronomical community that will help to catalyze exoplanet research and make the best use of Webb in the limited time we have available.”

For their first observation, the JWST will be responsible for characterizing a planet’s atmosphere by examining the light that passes through it. This happens whenever a planet transits in front of a star, and the way light is absorbed at different wavelengths provides clues as to the atmosphere’s chemical composition. Unfortunately, existing space telescopes have not had the necessary resolution to scan anything smaller than a gas giant.

The JWST, with its advanced infrared instruments, will examine the light passing through exoplanet atmospheres, split it into a rainbow spectrum, and then infer the atmospheres’ composition based on which sections of light are missing. For these observations, the project team selected WASP-79b, a Jupiter-sized exoplanet that orbits a star in the Eridanus constellation, roughly 780 light-years from Earth.

The team expects to detect and measure the abundances of water, carbon monoxide, and carbon dioxide in WASP-79b, but is also hoping to find molecules that have not yet been detected in exoplanet atmospheres. For their second observation, the team will be monitoring a “hot Jupiter” known as WASP-43b, a planet which orbits its star with a period of less than 20 hours.

Like all exoplanets that orbit closely to their stars, this gas giant is tidally-locked – where one side is always facing the star. When the planet is in front of the star, astronomers are only able to see its cooler backside; but as it orbits, the hot day-side slowly comes into view. By observing this planet for the entirety of its orbit, astronomers will be able to observe those variations (known as a phase curve) and use the data to map the planet’s temperature, clouds, and atmospheric chemistry.

This data will allow them to sample the atmosphere to different depths and obtain a more complete picture of the planet’s internal structure. As Bean indicated:

“We have already seen dramatic and unexpected variations for this planet with Hubble and Spitzer. With Webb we will reveal these variations in significantly greater detail to understand the physical processes that are responsible.”

*An exoplanet about ten times Jupiter’s mass located some 330 light years from Earth. X-ray: NASA/CXC/SAO/I.Pillitteri et al; Optical: DSS; Illustration: NASA/CXC/M.Weiss*

For their third observation, the team will be attempting to observe a transiting planet directly. This is very challenging, seeing as how the star’s light is much brighter and therefore obscures the faint light being reflected off the planet’s atmosphere. One method for addressing this is to measure the light coming from a star when the planet is visible, and again when it disappears behind the star.

By comparing the two measurements, astronomers can calculate how much light is coming from the planet alone. This technique works best for very hot planets that glow brightly in infrared light, which is why they selected WASP-18b for this observation – a hot Jupiter that reaches temperatures of around 2,900 K (2627 °C; 4,800 °F). In the process, they hope to determine the composition of the planet’s smothering stratosphere.

In the end, these observations will help test the abilities of the JWST and calibrate its instruments. The ultimate goal will be to examine the atmospheres of potentially-habitable exoplanets, which in this case will include rocky (aka. “Earth-like”) planets that orbit low mass, dimmer red dwarf stars. In addition to being the most common star in our galaxy, red dwarfs are also believed to be the most likely place to find Earth-like planets.

Image: James Webb Space Telescope — NASA’s James Webb Telescope, shown in this artist’s conception, will provide more information about previously detected exoplanets. Beyond 2020, many more next-generation space telescopes are expected to build on what it discovers. Credit: NASA

As Kevin Stevenson, a researcher with the Space Telescope Science Institute and a co-principal investigator on the project, explained:

“TESS should locate more than a dozen planets orbiting in the habitable zones of red dwarfs, a few of which might actually be habitable. We want to learn whether those planets have atmospheres and Webb will be the one to tell us. The results will go a long way towards answering the question of whether conditions favorable to life are common in our galaxy.”

The James Webb Space Telescope will be the world’s premier space science observatory once deployed, and will help astronomers to solve mysteries in our Solar System, study exoplanets, and observe the very earliest periods of the Universe to determine how its large-scale structure evolved over time. For this reason, its understandable why NASA is asking that the astronomical community be patient until they are sure it will deploy successfully.

When the payoff is nothing short of ground-breaking discoveries, it’s only fair that we be willing to wait. In the meantime, be sure to check out this video about how scientists study exoplanet atmospheres, courtesy of the Space Telescope Science Institute:

Further Reading: NASA

July 18, 2018 by David Dickinson

Enter the Red Planet: Our Guide to Mars Opposition 2018

Mars Dust Storm — A dusty view of Mars from July 11th. Image credit and copyright: Waskogm.

Have you checked out Mars this season? Mars reaches opposition on July 27th at 5:00 Universal Time (UT) shining at magnitude -2.8 and appearing 24.3” across—nearly as large as it can appear, and the largest since the historic opposition of 2003. We won’t have an opposition this favorable again until September 15^th, 2035.

Mars starts this week near the +4th magnitude star Psi Capricorni, loops westward through retrograde briefly into the astronomical constellation of Sagittarius the Archer in late August before heading back into Capricornus in September.

Mars opened up 2018 just 4.8” across, trekking through the early dawn sky. What a difference a few months make: Mars broke 15” arc seconds—a maximum size for an unfavorable opposition near aphelion—on May 30^th, and now dominates the summer sky around midnight.

Path of Mars — The path of Mars from July through September 2018. Credit: Starry Night.

There’s one downside, however, to the 2018 opposition of Mars: it’s occurring very nearly as far south along the ecliptic as it can. This is great news for observers in Australia, South Africa and South America, as the Red Planet rides high near the zenith at local midnight. Up north, however, we are still looking at Mars through the murk of the atmosphere lower to the horizon. For example, here in Norfolk, Virginia at latitude 37 degrees north, we never see Mars rise more than 29 degrees altitude above the southern horizon this season.

Down with Dust Storms

Does Mars seem a bit… peachy colored to you this season? It’s not your imagination: a planetary dust storm is indeed underway. It’s the middle of autumn for northern hemisphere of Mars, and this seems to be shaping up to be one of those oppositions where the planet, though at its closest, presents a featureless, dust-shrouded disk. This seems to be the case roughly every third opposition or so… our best hope now is that it may clear in the coming final weeks of July. We checked out Mars over the past weekend, and could just spy the pole cap and some slight detail under a veil of haze.

Curiosity dust storm — The Curiosity rover’s dusty view from late June. Credit: NASA

Despite the depiction of Martian dust storms in science fiction blockbusters such as The Martian as furious and unrelenting, these storms are actually pretty mild-mannered, barely able to chase a leaf before them through the tenuous Martian atmosphere, if deciduous trees grew on Mars. One thing Martian dust storms can do, however, is coat solar panels with a battery-killing film, and it has yet to be seen if the aging Opportunity rover will awaken and phone home from Meridiani Planum.

Unlike the Earth, Mars has a markedly elliptical orbit, varying from 1.7 (AU) astronomical units from the Sun at aphelion to 1.4 AU near perihelion. This all means that not every opposition of Mars is equal; in fact, Mars can range from 55 million to 102 million kilometers from the Earth near opposition and appear 13.8” to 25.1” across, depending on where it’s at in its orbit. And although Mars laps the Earth roughly every 26 months, a cycle of favorable oppositions repeat every 15 years.

Mars 2018 — Still dusty… Mars from July 16th. Image credit and copyright: Shahrin Ahmad.

In 2018, Mars reaches opposition on July 27th at 5:00 UT/1:00 AM EDT 57.8 million kilometers from the Earth, then makes its closest approach four days later on July 31^st at 8:00 UT/4:00 AM EDT, 57.6 million kilometers distant. Why the discrepancy? Well, opposition is simply reckoned as the point where an outer planet reaches an ecliptic longitude of 180 degrees opposite from the Sun. Mars, however, is still headed inward towards perihelion on September 16^th, while Earth just came off of aphelion on July 6^th.

Visually, Mars can on occasion “go yellow” and present a saffron color even to the naked eye if a planetary wide sandstorm is underway. At the eyepiece, the most prominent feature is always the pole cap, a white dollop on the planet’s pumpkin hued limb. Crank up the magnification, and dark patches come into view, as Mars is the only planet in the solar system presenting an actual surface available for amateur scrutiny. Mars has a day very similar to Earth’s at only 37 minutes longer in duration, meaning that if you observe Mars at the same time every evening, you’ll see nearly the same longitude of the planet turned towards you, shifted 10 degrees westward. A great tool for comparing what features on Mars are currently turned Earthward is Mars Previewer.

Can you spy Mars… daytime? This month is a good time to try, as it currently shines brighter than Jupiter. The easiest thing to do is lock on to it with a telescope near dawn as it sets to the west and the Sun rises in the east, then simply track it into the daytime sky. We’ve seen Mars in 2003 and again this year while the Sun is still above the horizon… having the Moon nearby also helps, though of course, Mars is very close to the horizon at sunset/sunrise right at opposition.

And speaking of which, viewers in Europe, Africa, Asia and Australia are in for a special treat on the evening of July 27^th, as a total eclipse of the Moon occurs just 15 hours after Mars passes opposition. Ironically, this is also a Minimoon eclipse, as the Moon also passes apogee just 14 hours prior to entering the Earth’s shadow. Expect to see the Red Planet just seven degrees from the blood red Moon at mid-eclipse (more on the eclipse next week).

eclipse vs mars — Mars versus the total lunar eclipse on the night of July 27th. Credit: Stellarium

The Moon won’t occult (pass in front of) Mars again until November 16^th, 2018 for the very southernmost tip of South America. Stick around until July 26^th, 2344 AD, and you can witness the Moon occulting the planet Saturn during an eclipse, though you’ll have to journey to southern Japan to do it.

But you may not have to wait that long… stick around until April 27th, 2078, and you can witness the Moon occult Mars… during a penumbral lunar eclipse:

The April 27th, 2078 occultation of Mars… during a penumbral lunar eclipse. Credit: NASA/GSFC/Occult 4.2/Starry Night

This current evening apparition of Mars ends over a year from now on September 2^nd, 2019, as Mars reaches solar conjunction on the farside of the Sun.

Finally, opposition is a great time to try and check the tiny Martian moons Phobos and Deimos off of your life list. These two moons were actually discovered by Asaph Hall from the United States Naval Observatory’s newly installed 26-inch refractor during a favorable parihelic apparition of Mars in 1877.

Shining at magnitude +12.4 (Deimos) and +11.3 (Phobos), seeing these moons would be a cinch… were it not for the presence of Mars shining a million times brighter nearby. Your best bet is to construct an occulting bar eyepiece (we’ve used a thin strip of foil and a guitar string affixed to an eyepiece to accomplish this) or simply place brilliant Mars just out of view. Phobos orbits once every 7.7 hours and substends 20” from the disk of Mars, while Deimos goes around Mars once every 30.35 hours and journeys 66” with each elongation from the Martian disk. PDS rings node or a good planetarium program such as Starry Night or Stellarium will show the current orientation of the Martian moons, aiding in your decision of whether or not to take up the quest.

Don’t miss out on Mars this opposition season… it’ll be almost another two decades before we get another favorable view.

Read all about viewing the planets, from observation to imaging and sketching in our new book: The Universe Today Guide to the Cosmos out October 23^rd, now available for pre-order.

July 17, 2018 by Matt Williams

NASA’s Juno Mission Spots Another Possible Volcano on Jupiter’s Moon Io

Infrared image of the southern hemisphere of Jupiter’s moon Io taken by NASA's Juno spacecraft on Dec. 16, 2017. Credits: NASA/JPL-Caltech/SwRI/ASI/INAF/JIRAM

When the Juno spacecraft arrived in orbit around Jupiter in 2016, it became the second spacecraft in history to study Jupiter directly – the first being the Galileo probe, which orbited Jupiter between 1995 and 2003. With every passing orbit (known as a perijove, which take place every 53 days), the spacecraft has revealed more about Jupiter’s atmosphere, weather patterns, and magnetic environment.

In addition, Juno recently discovered something interesting about Jupiter’s closest orbiting moon Io. Based on data collected by its Jovian InfraRed Auroral Mapper (JIRAM) instrument, Juno detected a new heat source close to the south pole of Io that could indicate the presence of a previously undiscovered volcano. This is just the latest discovery made by the probe during its mission, which NASA recently extended to 2021.

*Annotated image of the new heat source in the southern hemisphere of the Jupiter moon Io. Credits: NASA/JPL-Caltech/SwRI/ASI/INAF/JIRAM*

The infrared data was collected on Dec. 16th, 2017, when the Juno spacecraft was about 470,000 km (290,000 mi) away from Io. As Alessandro Mura, a Juno co-investigator from the National Institute for Astrophysics (INAF) in Rome, explained in a recent NASA press release:

“The new Io hotspot JIRAM picked up is about 200 miles (300 kilometers) from the nearest previously mapped hotspot. We are not ruling out movement or modification of a previously discovered hot spot, but it is difficult to imagine one could travel such a distance and still be considered the same feature.”

Aside from Juno and Galileo, many NASA missions have visited or passed through the Jovian System in the past few decades. These have including the Pioneer 10 and 11 missions in 1973/74, the Voyager 1 and 2 missions in 1979, and the Cassini and New Horizons missions in 2000 and 2007, respectively. Each of these missions managed to snap pictures of the Jovians moons on their way to the outer Solar System.

*Annotated image of the new heat source close to the south pole of Io, with a scale depicting the range of temperatures displayed in the infrared image. Credits: NASA/JPL-Caltech/SwRI/ASI/INAF/JIRAM*

Combined with ground-based observations, scientists have accounted for over 150 volcanoes on the surface of Io so far, with estimates claiming there could over 400 in total. Since it entered Jupiter’s orbit on July 4th, 2016, the Juno probe has traveled nearly 235 million km (146 million mi) from one pole to other. On July 16th, Juno will conduct its 13th perijove maneuver, once again passing low over Jupiter’s cloud tops at a distance of about 3,400 km (2,100 mi).

During these flybys, Juno probes beneath the upper atmosphere to study the planet’s auroras to learn more about it’s structure, atmosphere and magnetosphere. By shedding light on these characteristics, the Juno probe will also teach us more about the planet’s origins and evolution. This in turn will teach scientists a great deal more about the formation and evolution of our Solar System, and perhaps how life began here.

Further Reading: NASA