Portrait, attributed to Murillo, of Galileo gazing at the words “E pur si muove” (“And yet it moves;” not legible in this image) scratched on the wall of his prison cell. Image via Wikimedia Commons.

Happy birthday to Italian astronomer, mathematician, and physicist Galileo Galilei, born on February 15, 1564. Galileo was one of the first to aim a telescope at the night sky, where he saw phases of Venus and four dots of light orbiting Jupiter (now known as Jupiter’s famous Galilean moons). These and other observations began to change the way we saw the universe and our place in it.

In Galileo’s time, educated people subscribed to the Aristotelian view that Earth lay fixed in the center of a more or less unchanging universe. So his discovery of moons orbiting Jupiter (now known as the Galilean satellites in his honor) and Venus’s phases resulting from the planet orbiting the sun were considered heresy by the Roman Inquisition. In 1633, these tribunals – which had been developed by the Holy See of the Roman Catholic Church – forced Galileo to recant.

As he left the courtroom, he is famously said to have muttered:

E pur si muove (and yet it moves).

And so it does. Earth moves, and all objects in space move. The phrase is still used today as a retort, implying it doesn’t matter what you believe; these are the facts.

Galileo spent the rest of his life under house arrest, but that did not stop him from publishing another work, Two New Sciences, about mechanics and motion.

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Galileo grew up in a musical family. In 1574, the family moved to Florence, where 18-year-old Galileo began his education in a monastery. He was very successful in his studies and began studying medicine at the University of Pisa. Due to financial problems, he was unable to finish his degree, but his years at the university were priceless. They introduced him to mathematics and physics, but most importantly, they introduced him to Aristotle’s philosophy.

Back then, if somebody wished to know about the universe, the way to do it was to read Aristotle’s works. As Dante had put it some centuries before, Aristotle is “the Master of those who know” (Dante, Inferno 4.131). In other words, at that time, knowledge was to philosophy what faith was to religion.

And so, in spite of not being able to complete his degree in medicine and become a university professor, Galileo still continued his studies of mathematics. He was able to get a few minor teaching positions for a living. After two years of hard work, he published “La Bilancetta” (The Little Balance), his first scientific book, which gained him a reputation. The book commented upon the story of how the king of Syracuse asked Archimedes to verify whether his crown was made of pure gold or a lower-value mix of metals. Galileo presented an invention of his, the “little balance,” today called “hydrostatic balance,” that is used to make more accurate measurements of differences in density.

Read here about the King’s crown and Archimedes’ other discoveries.

Galileo’s reputation was bruised after the publication of his “Du Motu” (On Motion), a study of falling objects, which showed his disagreement with the Aristotelian view about the subject.

In 1609, he heard that in the Netherlands, an instrument had been invented that showed distant objects as if they were close by. Like many others, Galileo quickly figured out the mechanics of the spyglass, but later on he greatly improved the original design. He presented the Venetian State with an eight-powered telescope, a telescope that magnifies normal vision by eight times. His telescope earned him a doubling of his salary and a life tenure at Padua University.

Over the years, Galileo improved his telescope to magnify up to 20 times.

One of Galileo’s telescopes. Image via the University of Oregon.

With his telescope, he made many astronomical discoveries. For example, he was the first to view the moon magnified 20 times. He drew the moon’s surface, showing that its surface is bumpy and rocky, contrary to the popular belief of the time that the moon was smooth.

In January 1610, he discovered the four most massive moons of Jupiter: Io, Europa, Ganymede, and Callisto. Today, they are referred to as the Galilean moons. He laid out all of his findings in his book “Sidereus Nuncius” (The Starry Messenger).

Galileo observed that Venus went through phases, just as the moon does.

Composite image showing spacecraft views of the four largest moons of Jupiter. Known as the Galilean satellites, they were first seen by the Italian astronomer Galileo Galilei in 1610. Shown from left to right in order of increasing distance from Jupiter. Io is closest, followed by Europa, Ganymede and Callisto. Image via NASA.

Galileo was a respected man by 1610, but his increasingly public acceptance of the heliocentric system began to cause him trouble with the Roman Catholic Church.

In 1618, Galileo was dragged into a controversy about the nature of comets, which was of no help to his social position. Galileo nevertheless published the argument under his own name in “Il Saggitore” (The Assayer) in 1623, which is to this day one of his best-known pieces of work.

Read selections from “The Assayer.”

Things didn’t get much better for Galileo before his death in 1642. His work kept defying the accepted Aristotelian view and earned him the anger of the Roman Catholic Church, which had founded a group of institutions within the Church’s judicial system – known as the Inquisition – whose whose aim was to combat heresy.

In particular his 1632 publication of his “Dialogue Concerning the Two Chief World Systems, Copernican and Ptolemaic” opposed the Aristotelian view. In 1633, the Inquisition summoned Galileo to Rome. He was declared a suspect of heresy, was punished by life imprisonment, and was made to abjure formally. Nevertheless, he lived comfortably and was allowed to continue his work.

Galileo’s daughter, Sister Maria Celeste, was a nun in the Catholic Church. They regularly wrote each other letters, and she saved the letters Galileo wrote her, which were eventually published in a book in 1999 by Dava Sobel called Galileo’s Daughter.

Despite Galileo’s battles with the church, he was a committed Catholic. He would probably be pleased to know that the Vatican now has its own observatory and some of its fathers are astronomers. But it took until 1992 before the Vatican admitted that Galileo was right in his heliocentric beliefs.

Galileo died on January 8, 1642.

A list of all of Galileo’s discoveries is lengthy. Although Galileo is greatly praised for his various scientific discoveries, he did much more than just push science forward: He also pushed society forward. His life was much more than just a conflict with religion and Aristotelianism. It was a fight against the suppression of the opinion of an emerging scientific minority.

Galileo was one of the first to free science from philosophy. He inspired countless others to pursue the freedom of scientific inquiry.

Portrait of Galileo by Justus Sustermans. Image via Wikimedia Commons.

Bottom line: One of our greatest astronomers, Galileo Galilei, was born February 15, 1564. His discoveries with the improved telescopes he made has changed the way we view the universe.

Source:
https://earthsky.org/human-world/galileos-birthday-feb-15-1564

Read more of this story at Slashdot.

Source:
https://science.slashdot.org/story/21/01/12/1844246/insight-and-juno-keep-on-trucking?utm_source=rss1.0mainlinkanon&utm_medium=feed

Composite image of Io and Jupiter (Jupiter image from the Cassini spacecraft, Io image from the new research). Sulfur dioxide plumes from Io’s volcanoes are seen in yellow. Image via ALMA (ESO/ NAOJ/ NRAO)/ I. de Pater et al./ NRAO/ AUI NSF/ S. Dagnello/ NASA/ ESA/ UC Berkeley.

Io, one of the four large Galilean moons of Jupiter, is the most volcanically active body in our solar system, even more so than Earth. It has over 400 active volcanoes and is often described as hellish. Io also has an extremely thin atmosphere, composed mostly of sulfur dioxide (SO2). This little world’s volcanoes regularly spew sulfur dioxide into its atmosphere. Still, scientists weren’t sure whether the atmosphere stems from hot sulfur dioxide coming directly from the volcanoes, or cold sulfur dioxide which accumulates on Io’s surface and freezes before sublimating into the atmosphere. Now they’ve determined it’s both.

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Using the ALMA telescope in Chile, researchers at the University of California, Berkeley have announced that up to half of the sulfur dioxide in Io’s atmosphere comes directly from its volcanoes. The results have been published in two new peer-reviewed papers accepted for publication in The Planetary Science Journal, which you can read here and here.

Astronomer Imke de Pater, who led the study, said in a statement:

It was not known which process drives the dynamics in Io’s atmosphere. Is it volcanic activity, or gas that sublimates from the icy surface when Io is in sunlight? What we show is that, actually, volcanoes do have a large impact on the atmosphere.

The answer, it turns out, is both.

Some of the sulfur dioxide does indeed freeze out onto the surface, the researchers found. This happens when Io passes through Jupiter’s shadow every 42 hours. When Io was being observed by the researchers on March 20, 2018, they noticed that radio emissions from the sulfur dioxide dropped exponentially. This meant that Io’s lower atmosphere, 6-12 miles (10-20 km) in altitude, collapsed and froze onto the surface.

The temperature during this period fell to -270 degrees Fahrenheit (-168 degrees Celsius), cold enough for sulfur dioxide to freeze. Io’s surface is typically about -230 degrees Fahrenheit (-150 degrees Celsius). Cold, but not quite cold enough for the sulfur dioxide to freeze out.

On September 2 and 11, 2018, the sulfur dioxide emissions rose again within 10 minutes after Io emerged from Jupiter’s shadow back into sunlight. De Pater said:

As soon as Io gets into sunlight, the temperature increases, and you get all this SO2 ice subliming into gas, and you reform the atmosphere in about 10 minutes’ time, faster than what models had predicted.

That explains where some of the frozen sulfur dioxide comes from. But the researchers noticed something else as well. ALMA detected abundant sulfur dioxide over the volcanoes, as well as low levels of the gas globally in Io’s atmosphere. This suggested that the more widespread gas was originating from unseen or “stealth” volcanoes. They emit sulfur dioxide, but not other smoke or particles that can be easily seen.

Right now, the researchers think that extra gas is coming from such stealth volcanoes, although they couldn’t completely rule out the possibility that it could be sulfur dioxide that isn’t completely condensing out onto the surface. As de Pater noted:

The SO2 that we see with ALMA when Io is in eclipse is at a very low level, and we can’t say if that is stealth volcanism or caused by SO2 not completely condensing out.

Io, as seen by the Galileo spacecraft on September 19, 1997. Image via NASA/ JPL/ University of Arizona/ NASA Photojournal.

Earlier observations from the Keck Observatory from last July, however, supported the stealth volcanism scenario. Keck detected abundant sulfur monoxide (SO) over the volcanoes, as well as widespread in the atmosphere. The researchers say that sunlight breaks the sulfur-oxygen bond in the sulfur dioxide that has been ejected hundreds of kilometers above the surface, creating the sulfur monoxide. De Pater said:

But then, when we looked at the SO with Keck, we can only explain the SO emissions, which are widespread on the surface, through this stealth volcanism, because excitation of the SO requires a very high temperature.

By observing Io in its orbit around Jupiter as it moved into and then out of Jupiter’s shadow, the researchers were able to figure out how much of the moon’s sulfur dioxide deposits came from freezing out on the surface and how much came from stealth or other volcanoes. Statia Luszcz-Cook from Columbia University in New York said:

When Io passes into Jupiter’s shadow, and is out of direct sunlight, it is too cold for sulfur dioxide gas, and it condenses onto Io’s surface. During that time, we can only see volcanically-sourced sulfur dioxide. We can, therefore, see exactly how much of the atmosphere is impacted by volcanic activity.

A volcanic eruption on Io, caught by Galileo’s cameras on June 28, 1997. Image via NASA.

A closer look from Galileo at one of Io’s volcanoes, called Pele, as it was erupting. Image via NASA/ JPL/ USGS.

By using ALMA, scientists were able to “see,” for the first time, plumes of both sulfur dioxide and sulfur monoxide coming up from Io’s volcanoes. Two of those volcanoes, Karei Patera and Daedalus Patera, were erupting in March, and a third volcano was active in September.

The researchers now calculate that 30% to 50% of Io’s atmosphere is produced directly by active volcanoes.

A third gas, potassium chloride (KCI), was also detected by ALMA, and is a common component of lava. According to Luszcz-Cook:

We see KCI in volcanic regions where we do not see SO2 or SO. This is strong evidence that the magma reservoirs are different under different volcanoes.

Katherine de Kleer at the California Institute of Technology added:

By studying Io’s atmosphere and volcanic activity, we can understand more about the volcanoes, the tidal heating process and Io’s interior.

The volcano Loki Patera, as seen by Voyager 1 in 1979. The dark U-shaped feature is a lava lake about 124 miles (200 km) across. Image via NASA/ JPL/ USGS/ Planetary Science Institute.

Infrared view of Io’s active volcanoes from NASA’s Juno spacecraft, currently orbiting Jupiter. Wow! Image via NASA/ JPL-Caltech/ SwRI/ INAF/ The Planetary Society.

The scientists are eager to learn more about Io’s magma as well, and are planning to observe the moon at additional radio wavelengths. These can probe several inches beneath the surface and provide clues about what Io’s magma is composed of and its temperature. They also want to know more about the temperature of Io’s lower atmosphere. De Pater said:

To measure the temperature of Io’s atmosphere, we need to obtain a higher resolution in our observations, which requires that we observe the moon for a longer period of time. We can only do this when Io is in sunlight, since it does not spend much time in eclipse. During such an observation, Io will rotate by tens of degrees. We will need to apply software that helps us make unsmeared images. We have done this previously with radio images of Jupiter made with ALMA and the Very Large Array.

How can a small moon like Io, way out in the outer solar system, have active volcanoes? Io is volcanically active due to tidal heating. The same side of Io faces Jupiter, just like the same side of the moon always faces Earth. The gravitational pull of Jupiter, as well as the moons Europa and Ganymede, creates tremendous friction and heating inside Io.

Io was last observed up close by NASA’s Galileo mission in the late 1990s/early 2000s. The current Juno orbiter has seen Io from farther away, but its primary mission is to observe Jupiter itself in detail as it orbits the giant planet. It has taken some cool images from a distance though.

Imke de Pater at the University of California, Berkeley, who lead the new study. Image via UC Berkeley.

The new results help to solve the mystery of how Io’s atmosphere forms and how its volcanoes play a major part in that. But there are still many more questions to be answered – and new ones to be asked – about the solar system’s most active volcanic hotspot.

Bottom line: Active volcanoes produce almost half of Io’s sulfur atmosphere, according to new observations using ALMA.

Source: ALMA Observations of Io Going into and Coming out of Eclipse

Source: High Spatial and Spectral Resolution Observations of the Forbidden 1.707 um Rovibronic SO Emissions on Io: Evidence for Widespread Stealth Volcanism*

Via UC Berkeley

Via NRAO

Source:
https://earthsky.org/space/io-sulfur-volcanoes-hot-so2-cold-so2

Artist’s concept of K2-315b, which has on orbital period of 3.14 Earth-days, the same value as the mathematical constant pi. Image via NASA Ames/ JPL-Caltech/ T. Pyle/ Christine Daniloff/ MIT.

If you love both exoplanets and math, you’ll love this. In recent years, scientists have discovered a growing number of Earth-sized worlds orbiting distant stars. Now scientists at the Massachusetts Institute of Technology (MIT) have announced one whose orbital period matches the value of pi: that is, this planet orbits its star every 3.14 Earth-days. For those not mathematically inclined … pi is the numerical sequence that describes the ratio of the circumference of any circle to the diameter of that circle. No matter how big or little the circle may be, this ratio will always equal pi. And that makes pi one of the most important mathematical constants. The exoplanet is labeled K2-315b, but scientists are calling it the pi planet.

The pi planet was discussed in a new peer-reviewed paper published in The Astronomical Journal on September 21, 2020.

As Prajwal Niraula, lead author at MIT, noted in a statement:

The planet moves like clockwork.

Co-author Julien de Wit said:

Everyone needs a bit of fun these days.

Indeed, no one is suggesting that there is anything too bizarre about this, or that aliens are involved, since many exoplanets have been discovered with very short orbital periods like this. This one just happens to match the value of pi. Go figure.

The pi planet – K2-315b – is almost the same size as Earth; its radius is 95% that of our own planet. That’s also about the same size as Venus, and like our nearby sister world, it is a blisteringly hot place, with temperatures up to 350 degrees Fahrenheit (177 degrees Celsius). Not quite as hot as Venus, but still very inhospitable. It orbits a red dwarf (or M dwarf) star that is cooler than our sun and only about one-fifth as large, called EPIC 249631677, which is 186 light-years (57 parsecs) from Earth. The tight orbit of only 3.14 days means that the planet is moving fast around its star, at 181,000 miles per hour (291 km per hour). But even though scientists think that this world is rocky, like Earth, the close proximity to its star and resulting searing temperatures make it very unlikely to be habitable for any kind of life.

K2-315b was first discovered in 2017 in archival data from the Kepler Space Telescope (pictured here in artist’s illustration). Image via NASA/ Ames Research Center.

Niraula said:

This would be too hot to be habitable in the common understanding of the phrase.

K2-315b was discovered in data first obtained by NASA’s Kepler Space Telescope back in 2017, during the K2 extended mission, which ended in 2018. It was considered to be a candidate planet, but then subsequent observations by SPECULOOS (The Search for habitable Planets EClipsing ULtra-cOOl Stars), a network of ground-based telescopes, confirmed it as a planet. There are four 1-meter telescopes at the Paranal Observatory in Chile, named after the four Galilean moons of Jupiter: Io, Europa, Ganymede and Callisto. There is also one more identical telescope called Artemis in Tenerife, Spain. The finding also shows how valuable archival data can be. As de Wit commented:

We now know we can mine and extract planets from archival data, and hopefully there will be no planets left behind, especially these really important ones that have a high impact.

While looking through the old data, Niraula found 20 dips of the star, which occurred when the planet transited in front of it from our vantage point. Those dips repeated every 3.14 days, indicating a probable planet orbiting the star. In order to be sure, however, the researchers needed to determine the best window of time in which to catch the transits. As another co-author, Benjamin Rackham, said:

Nailing down the best night to follow up from the ground is a little bit tricky. Even when you see this 3.14 day signal in the K2 data, there’s an uncertainty to that, which adds up with every orbit.

The four 1-meter SPECULOOS telescopes at the Paranal Observatory in Chile were used to help confirm the existence of the pi-Earth exoplanet. Image via ESO/ Wikipedia.

Rackham had developed a new algorithm to try to predict when the transits would occur. As it turned out, February 2020 should be a good time to catch these transits, and it worked. The researchers saw three clear transits: two with the SPECULOOS’ telescopes in the Southern Hemisphere, and the third from Artemis, in the Northern Hemisphere.

The confirmation of this planet by SPECULOOS isn’t too surprising, since those telescopes are designed to detect Earth-sized planets around nearby dwarf stars. Another co-author, Artem Burdanov, said:

These ultracool dwarfs are scattered all across the sky. Targeted ground-based surveys like SPECULOOS are helpful because we can look at these ultracool dwarfs one by one.

The planet is also close enough that scientists using the upcoming James Webb Space Telescope (JWST) should be able to analyze its atmosphere. There’s also a good chance that even smaller planets will be found. From the paper:

The confirmed planet is well suited for comparative terrestrial exoplanetology. While exoplanets transiting ultracool dwarfs present the best opportunity for atmospheric studies of terrestrial exoplanets with the James Webb Space Telescope, those orbiting mid-M dwarfs within 100 parsecs such as EPIC 249631677b will become increasingly accessible with the next generation of observatories.

Prajwal Niraula at MIT, lead author of the new study. Image via EAPS/ MIT.

As Niraula also noted:

There will be more interesting planets in the future, just in time for JWST, a telescope designed to probe the atmosphere of these alien worlds. With better algorithms, hopefully one day, we can look for smaller planets, even as small as Mars.

While the orbit of K2-315b matching the beginning of the pi mathematical constant may be a fun coincidence, the discovery also shows, again, that there are many Earth-sized worlds out there waiting to be found. A quickly growing number have already been discovered, and scientists fully expect that many more will be as well in the years ahead.

Bottom line: Astronomers have discovered an Earth-sized exoplanet with an orbital period that matches the mathematical constant pi.

Source: Pi Earth is a 3.14-day Earth-sized planet from K2’s kitchen, served warm by the SPECULOOS team

Via MIT

Source:
https://earthsky.org/space/pi-exoplanet-k2-315b-has-3-14-day-orbit

On September 23, 24, 25 and 26, 2020, look for the moon in the evening sky, and it’ll guide you to Jupiter and Saturn, our solar system’s two biggest gas giant planets. Given clear skies, you can’t miss these bright worlds. The moon is the second-brightest celestial object, after the sun. And Jupiter is exceptionally bright, too, outshining all the stars (but just a hair less bright than dazzling Mars; more about Mars below). As for Saturn, it’s as bright as the brightest stars. Plus Jupiter and Saturn are noticeable now for their nearness to each other. They’re headed for a great conjunction before 2020 ends.

So you just can’t miss or mistake Jupiter and Saturn near the moon on these evenings. Watch for them!

As viewed from the mainland United States, the moon reaches its first quarter phase on September 23, 2020, at 9:55 p.m. EDT, 8:55 p.m. CDT, 7:55 p.m. MDT and 6:55 p.m. PDT. By Universal Time (UTC), the moon reaches its first quarter phase on September 24, 2020, at 01:55 UTC. At first quarter, the one half of the moon is illuminated in sunshine while the dark half is engulfed in the moon’s own shadow.

The dark side of a waxing moon always points east (the direction of your sunrise). And the moon in its orbit always travels toward the east, too, relative to the sky background. The moon travels about 1/2 degree eastward – its own width on our sky’s dome – every hour.

So – on these evenings in late September 2020 – the moon will go past Jupiter, and then it’ll go by Saturn.

View at EarthSky Community Photos. | Javier Elias captured this image on August 21, 2020, at Costa Ballena Beach in Chipiona, Cadiz, Spain. You can see Jupiter and Saturn to the left of the Milky Way, as the 2 brightest “stars” in the photo. Thank you, Javier.

The moon will swing 1.6 degrees to the south of Jupiter on September 25, 2020, at 06:46 UTC. Then the moon will sweep 2.3 degrees to the south of Saturn on September 25, 2020, at 20:46 UTC. When an almanac gives the degree measure between the moon and a given planet, it means as viewed from the center of the Earth (not the Earth’s surface). Because the moon is close enough to Earth to display a parallax, the angular separation between the moon and planet can vary somewhat around the world.

A word about Mars now. There’s another very bright planet in the September evening sky. It’s Mars, now at its best for this two-year period. As you stand looking at the moon, Jupiter and Saturn, you’ll surely notice Mars to the east (toward your sunrise direction). Earth will pass between Mars and the sun in October, and the planet now outshines Jupiter. The moon will sweep past Mars, too, in late September and early October.

The full Harvest Moon will come on October 1 or 2, 2020, depending on your time zone. It’ll sweep past Mars, now fiery red and very bright! Read more.

Now let’s talk about what you can see through a telescope, if you have one. A telescope, even a modest backyard variety, works like a charm for viewing the moon, Jupiter and Saturn. Dust off that telescope and zoom in to scan the lunar terrain, the four major moons of Jupiter and Saturn’s rings.

The best time to view the moon – with a telescope, binoculars or just your eye – is in twilight. Moon-watching in a dark sky gives you a disadvantage, because the moon’s glare can be overwhelming. As for the best place on the moon to look with a telescope or binoculars, try looking along the terminator line, the shadow line that divides the lunar day from the lunar night. The long shadows along the lunar terminator provide a wondrous three-dimensional portrayal of the lunar mountains, craters and valleys.

View at EarthSky Community Photos. | Barb Stinehelfer in Upper Sandusky, Ohio, caught this shot on September 20, 2020. She wrote: “19.1% crescent moon complete with surprise photobomber.” Thank you, Barb!

Jupiter’s four major moons – Io, Europa, Ganymede and Callisto – are easy to see in a low-powered telescope, usually appearing as pinpoints of light strung out in a line (really, orbiting Jupiter more or less along a single plane). Sometimes, a moon or two might not be visible, because these Jovian moons regularly pass behind and in front of Jupiter.

Click here to find out the positions of these Galilean moons for right now or some chosen time, via SkyandTelescope.com.

View at EarthSky Community Photos. | Alexander Krivenyshev was creating a 9/11 tribute photo in New York City on September 11, 2020, when he also captured this image of Jupiter and several of its moons. Thank you, Alexander. Visit Sky & Telescope’s Jupiter moon calculator for the present position of Jupiter’s 4 major moons.

View at EarthSky Community Photos. | Kannan A in Woodlands, Singapore, caught this cool image of Jupiter – with the shadow of the Galilean moon Io cast on the planet – on September 19, 2020. He wrote: “This image of Jupiter was shot from my Nikon camera without the aid of any telescope or additional equipment.” Read more about this photo. Thank you, Kannan A!

Finally, aim your telescope at Saturn to see this planet’s glorious rings, which circle Saturn above this planet’s equator. Fortunately, in 2020, Saturn’s rings appear inclined at around 21 degrees in Earth’s sky, so they are quite easy to see now. There are years (2009, 2025) when Saturn’s rings appear edge-on in Earth’s sky. At those times, the rings become invisible. But not this year, because we enjoy a favorable inclination of the rings in 2020.

Best of all, we can enjoy observing the lunar landscape, Jupiter’s moons and Saturn’s rings in a sky that’s beset with moonlight or light pollution. These solar system wonders don’t demand the dark sky that far-off galaxies and nebulae do.

These images suggest how the ringed planet Saturn might look when seen through a 4-inch telescope (top) versus an an 8-inch telescope (bottom). Image via SkyandTelescope.com.

View at EarthSky Community Photos. | Saturn through an 8-inch telescope via Michael Terhune in Lunenburg, Massachusetts. He caught this photo on September 8, 2020, and wrote: “The planet Saturn … not much more to say.” So true! Thank you, Michael!

Bottom line: On September 23, 24, 25 and 26, 2020, use the moon to find the planets Jupiter and Saturn. Have a telescope? Then use it to view Jupiter’s four major moons and Saturn’s glorious rings.

Source:
https://earthsky.org/tonight/moon-jupiter-saturn-september-23-26

The north pole of Ganymede, as seen in the infrared by Juno on December 26, 2019. Image via NASA/ JPL-Caltech/ SwRI/ ASI/ INAF/ JIRAM.

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Ganymede is Jupiter’s largest moon, and the ninth-largest object in our solar system. This moon is even bigger than the planet Mercury. The last time we had good close-up images of it was from the Galileo mission to Jupiter in the late 1990s. Those images provided a detailed look at much of Ganymede’s surface, but Galileo never managed to capture Jupiter’s north pole. Now, thanks to NASA’s Juno spacecraft currently orbiting Jupiter, we have the first images of the north pole of this large Jovian moon.

Unlike the Galileo mission, Juno isn’t designed specifically to study Jupiter’s moons. Juno’s images aren’t as high-resolution as those of Galileo in the 1990s, in part because they were taken from farther away. And the Juno images show the view in infrared – showing the amount of heat radiated by Ganymede at various points near its pole – rather than being visible light images revealing what our eyes would see.

Still, the images provide a glimpse of this part of Ganymede that was unseen until now. The JIRAM instrument on the Juno spacecraft – aka the Jovian Infrared Auroral Mapper – acquired the images as part of the spacecraft’s mapping of the northern regions of the moon. JIRAM used high-contrast imaging and spectroscopy to study Jupiter’s polar regions during the December 26, 2019, flyby of Jupiter. At that time, Ganymede happened to be within view of Juno. The spacecraft was programmed to turn its instruments toward Ganymede during this time.

At closest approach to Ganymede – about 62,000 miles (100,000 km) – JIRAM collected 300 infrared images of the moon’s surface, with a spatial resolution of 14 miles (23 km) per pixel.

Now … what do the new images show?

Various infrared views of Ganymede’s north polar, captured by the Juno spacecraft on December 26, 2019. Image via NASA/ JPL-Caltech/ SwRI/ ASI/ INAF/ JIRAM.

We knew already that, like many moons in the outer solar system, Ganymede is composed largely of water ice. It’s thought to have a water ocean beneath an outer ice crust.

A significant finding from these new Juno images is that the ice at Ganymede’s north pole isn’t pristine. It’s been acted upon by plasma from Jupiter’s colossal magnetosphere, which is some 20,000 times stronger than Earth’s magnetosphere. Ganymede has only an extremely thin atmosphere, so plasma from Jupiter can reach the surface unimpeded, greatly affecting the surface ice. Alessandro Mura, a Juno co-investigator at the National Institute for Astrophysics in Rome, commented:

The JIRAM data show the ice at and surrounding Ganymede’s north pole has been modified by the precipitation of plasma. It is a phenomenon that we have been able to learn about for the first time with Juno because we are able to see the north pole in its entirety.

The researchers can also see that the ice near Ganymede’s north and south poles has a different infrared signature than ice at Ganymede’s equator. This polar ice is amorphous, that is, lacking a definite shape or form. The amorphousness is due to Ganymede’s being the only moon in the solar system with its own magnetic field. Charged particles follow the moon’s magnetic field lines to the poles, where they impact and wreak havoc on the ice, preventing it from having an ordered (or crystalline) structure.

Scientists have found that even frozen water molecules in these regions have no order in their arrangement.

The new data from Juno show how it can contribute to the study of Jupiter’s moons, even though its primary mission is the study of Jupiter itself. According to Giuseppe Sindoni, program manager of the JIRAM instrument for the Italian Space Agency:

These data are another example of the great science Juno is capable of when observing the moons of Jupiter.

Ganymede, as seen in enhanced color by the Galileo spacecraft in the late 1990s. Image via NASA/ Phys.org.

Another, natural color view of Ganymede from Galileo in the late 1990s. Image via NASA.

Artist’s concept of auroras on Ganymede. This is made possible by the fact that Ganymede is the only moon known to have a magnetic field. Image via NASA/ ESA.

Cross-section of Ganymede’s interior showing a subsurface ocean of water. Image via NASA/ ESA/ A. Feild (STScI)/ Space.com.

JIRAM’s primary task is to look at infrared light coming from within the deep atmosphere of Jupiter itself. It can probe down to 30 to 45 miles (50 to 70 km) below Jupiter’s cloud tops. But, along with Ganymede, the instrument can also be used to study the moons Io, Europa and Callisto. Those four moons are known as the Galilean moons, named after the astronomer Galileo who discovered them in 1610. They are the four largest moons of Jupiter.

Thanks to its magnetic field, Ganymede also has auroras, like Earth, even though its atmosphere is extremely tenuous and almost non-existent. Ganymede’s ocean is estimated to be 60 miles (100 km) thick – 10 times deeper than Earth’s oceans – and is buried under a 95-mile (150-km) crust of mostly ice.

With a diameter of 3,273 miles (5,268 km), it is 26% larger than the planet Mercury by volume, although it is only 45% as massive. Ganymede has an iron core, a rocky mantle surrounded by an ice mantle, a water ocean ocean surrounding the mantles and an ice crust on top.

Giuseppe Sindoni, program manager of the JIRAM instrument for the Italian Space Agency. Image via ResearchGate.

Juno can see Ganymede only from a distance, but the European Space Agency’s (ESA’s) JUpiter ICy moons Explorer (JUICE), scheduled for launch in 2022, will study Ganymede, Callisto and Europa in detail after it arrives at Jupiter in 2029. This will be the first such mission to do so since Galileo.

For now, Juno has provided at least a glimpse of Ganymede’s north pole for scientists to study. In the not-too-distant future, missions like JUICE will reveal much more about this tantalizing world.

Read more about NASA’s Juno mission.

Bottom line: NASA’s Juno spacecraft has taken the first-ever images of Ganymede’s north pole.

Via Jet Propulsion Laboratory

Source:
https://earthsky.org/space/ganymede-north-pole-infrared-images-juno-spacecraft-jupiter

Source:
https://www.unexplained-mysteries.com/news/337824/steam-powered-bot-could-explore-icy-moons

Source:
https://www.newscientist.com/article/mg24632871-600-why-icy-moons-like-europa-are-our-best-bet-for-finding-alien-life/?utm_campaign=RSS%7CNSNS&utm_source=NSNS&utm_medium=RSS&utm_content=home

Image via Silva.

You’ve probably got a pair of binoculars lying around your house somewhere. They might be perfect – that’s right, perfect – for stargazing.

Follow the links below to learn more about the best deal around for people who want to get acquainted with the night sky: a pair of ordinary binoculars.

1. Binoculars are a better place to start than telescopes

2. Start with a small, easy-to-use size

3. First, view the moon with binoculars.

4. Move on to viewing planets with binoculars.

5. Use your binoculars to explore inside our Milky Way.

6. Use your binoculars to peer beyond the Milky Way.

1. Binoculars are a better place to start than telescopes. The fact is that most people who think they want to buy a telescope would be better off using binoculars for a year or so instead.  That’s because first-time telescope users often find themselves completely confused – and ultimately put off – by the dual tasks of learning the use a complicated piece of equipment (the ‘scope) while at the same time learning to navigate an unknown realm (the night sky).

Beginning stargazers often find that an ordinary pair of binoculars – available from any discount store – can give them the experience they’re looking for.  After all, in astronomy, magnification and light-gathering power let you see more of what’s up there.  Even a moderate form of power, like those provided by a pair of 7×50 binoculars, reveals 7 times as much information as the unaided eye can see.

You also need to know where to look. Many people start with a planisphere as they begin their journey making friends with the stars.

You can purchase a planisphere at the EarthSky store. Also consider our Astronomy Kit, which has a booklet on what you can see with your binoculars.

2. Start with a small, easy-to-use size.  Don’t buy a huge pair of binoculars to start with! Unless you mount them on a tripod, they’ll shake and make your view of the heavens shaky, too. The video above – from ExpertVillage – does a good job summing up what you want. And in case you don’t want to watch the video, the answer is that 7×50 binoculars are optimum for budding astronomers.  You can see a lot, and you can hold them steadily enough that jitters don’t spoil your view of the sky.  Plus they’re very useful for daylight pursuits, like birdwatching. If 7x50s are too big for you – or if you want binoculars for a child – try 7x35s.

Read Sky & Telescope’s article on how to buy your first pair of binoculars

Moon with earthshine via Greg Diesel Landscape Photography.

3. First, view the moon with binoculars. When you start to stargaze, you’ll want to watch the phase of the moon carefully. If you want to see deep-sky objects inside our Milky Way galaxy – or outside the galaxy – you’ll want to avoid the moon. But the moon itself is a perfect target for beginning astronomers armed with binoculars. Hint: the best time to observe the moon is in twilight. Then the glare of the moon is not so great, and you’ll see more detail.

Click here to understand more about the moon’s phases.

An EarthSky lunar calendar can help, too, but we only offer them a certain times of year.  Click to see if they’re available.

You’ll want to start your moon-gazing when the moon is just past new – and visible as a waxing crescent in the western sky after sunset. At such times, you’ll have a beautiful view of earthshine on the moon.  This eerie glow on the moon’s darkened portion is really light reflected from Earth onto the moon’s surface.  Be sure to turn your binoculars on the moon at these times to enhance the view. 

Each month, as the moon goes through its regular phases, you can see the line of sunrise and sunset on the moon progress across the moon’s face. That’s just the line between light and dark on the moon. This line between the day and night sides of the moon is called the terminator line.  The best place to look at the moon from Earth – using your binoculars – is along the terminator line. The sun angle is very low in this twilight zone, just as the sun is low in our sky around earthly twilight.  So, along the terminator on the moon, lunar features cast long shadows in sharp relief.

You can also look in on the gray blotches on the moon called maria, named when early astronomers thought these lunar features were seas.  The maria are not seas, of course, and instead they’re now thought to have formed 3.5 billion years ago when asteroid-sized rocks hit the moon so hard that lava percolated up through cracks in the lunar crust and flooded the impact basins. These lava plains cooled and eventually formed the gray “seas” we see today.

The white highlands, nestled between the maria, are older terrain pockmarked by thousands of craters that formed over the eons. Some of the larger craters are visible in binoculars. One of them, Tycho, emanates long white rays for hundreds of miles over the adjacent highlands. This is material kicked out during the Tycho impact 2.5 million years ago.

View Larger. Photo of Jupiter’s moons by EarthSky Facebook friend Carl Galloway. Thank you, Carl! The four major moons of Jupiter are called Io, Europa, Ganymede and Callisto. This is a telescopic view, but you can glimpse one, two or more moons through your binoculars, too.

4. Move on to viewing planets with binoculars. Here’s the deal about planets.  They move around, apart from the fixed stars.  They are wanderers, right?

You can use our EarthSky Tonight page to locate planets visible around now.  Notice if any planets are mentioned in the calendar on the Tonight page, and if so click on that day’s link.  On our Tonight page, we feature planets on days when they’re easily identifiable, for example when a planet is near the moon.  So our Tonight page calendar can help you come to know the planets, and, as you’re learning to identify them, keep your binoculars very handy. Binoculars will enhance your view of a planet near the moon, for example, or two planets near each other in the twilight sky. They add a lot to the fun!

Below, you’ll find some more simple ideas on how to view planets with your binoculars.

Mercury and Venus. These are both inner planets.  They orbit the sun closer than Earth’s orbit.  And for that reason, both Mercury and Venus show phases as seen from Earth at certain times in their orbit, a few days before or after the planet passes between the sun and Earth.  At such times,  turn your binoculars on Mercury or Venus. Good optical quality helps here, but you should be able to see them in a crescent phase. Tip: Venus is so bright that its glare will overwhelm the view. Try looking in twilight instead of true darkness.

Mars. Mars – the red planet – really does look red, and using binoculars will intensify the color of this object (or of any colorful star). Mars also moves rapidly in front of the stars, and it’s fun to aim your binoculars in its direction when it’s passing near another bright star or planet.

Jupiter. Now on to the real action! Jupiter is a great binocular target, even for beginners. If you are sure to hold your binoculars steady as you peer at this bright planet, you should see four bright points of light near it. These are the Galilean satellites – four moons spotted through one of the first telescopes ever made, by the Italian astronomer Galileo. Note how their relative positions change from night to night as each moon moves around Jupiter in its own orbit.

Saturn.Although a small telescope is needed to see Saturn’s rings, you can use your binoculars to see Saturn’s beautiful golden color.  Experienced observers sometimes glimpse Saturn’s largest moon Titan with binoculars.  Also, good-quality high-powered binoculars – mounted on a tripod – will show you that Saturn is not round.  The rings give it an elliptical shape.

Uranus and Neptune. Some planets are squarely binocular and telescope targets. If you’re armed with a finder chart, two of them, Uranus and Neptune, are easy to spot in binoculars. Uranus might even look greenish, thanks to methane in the planet’s atmosphere. Once a year, Uranus is barely bright enough to glimpse with the unaided eye … use binoculars to find it first. Distant Neptune will always look like a star, even though it has an atmosphere practically identical to that of Uranus.

There are still other denizens of the solar system you can capture through binocs. Look for the occasional comet, which appears as a fuzzy blob of light. Then there are the asteroids. Fully 12 of them can be followed with binoculars when they are at their brightest. Because an asteroid looks star-like, the secret to confirming its presence is to sketch a star field through which it’s passing. Do this over subsequent nights; the star that changes position relative to the others is our solar system interloper.

The Milky Way arching over a Joshua tree, photographed by EarthSky Facebook friend Manish Mamtani. Visit Manish on Facebook.

Pleiades star cluster, also known as the Seven Sisters.

5. Use your binoculars to explore inside our Milky Way.  Binoculars can introduce you to many members of our home galaxy. A good place to start is with star clusters that are close to Earth. They cover a larger area of the sky than other, more distant clusters usually glimpsed through a telescope.

Beginning each autumn and into the spring, look for a tiny dipper-like cluster of stars called the Pleiades.  The cluster – sometimes also called the Seven Sisters – is noticeable for being small yet distinctively dipper-like. While most people say they see only six stars here with the unaided eye, binoculars reveal many more stars, plus a dainty chain of stars extending off to one side. The Pleiades star cluster looks big and distinctive because it’s relatively close, about 400 light-years from Earth. This dipper-shaped cluster is a true cluster of stars in space.  Its members were born around the same time and are still bound by gravity.  These stars are very young, on the order of 20 million years old, in contrast to the roughly 5 billion years for our sun.

Stars in a cluster all formed from the same gas cloud. You can also see what the Pleiades might have like in a primordial state by shifting your gaze to the prominent constellation Orion the Hunter. Look for Orion’s sword stars, just below his prominent belt stars. If the night is crisp and clear, and you’re away from urban streetlight glare, unaided eyes will show that the sword isn’t entirely composed of stars. Binoculars show a steady patch of glowing gas where, right at this moment, a star cluster is being born. It’s called the Orion Nebula. A summertime counterpart is the Lagoon Nebula, in Sagittarius the Archer.

With star factories like the Orion Nebula, we aren’t really seeing the young stars themselves. They are buried deep within the nebula, bathing the gas cloud with ultraviolet radiation and making it glow. In a few tens of thousands of years, stellar winds from these young, energetic stars will blow away their gaseous cocoons to reveal a newly minted star cluster.

Scan along the Milky Way to see still more sights that hint at our home galaxy’s complexity. First, there’s the Milky Way glow itself; just a casual glance through binoculars will reveal that it is still more stars we can’t resolve with our eyes … hundreds of thousands of them. Periodically, while scanning, you might sweep past what appears to be blob-like, black voids in the stellar sheen. These are dark, non-glowing pockets of gas and dust that we see silhouetted against the stellar backdrop. This is the stuff of future star and solar systems, just waiting around to coalesce into new suns.

Andromeda Galaxy from Chris Levitan Photography.

Many people use the M- or W-shaped constellation Cassiopeia to find the Andromeda Galaxy. See how the star Schedar points to the galaxy?

6. Use your binoculars to view beyond the Milky Way.  Let’s leap out of our galaxy for the final stop in our binocular tour. Throughout fall and winter, Andromeda the Princess reigns high in the sky during Northern Hemisphere autumns and winters. Centered in the star pattern is an oval patch of light, readily visible to the unaided eye away from urban lights. Binoculars will show it even better.

It’s a whole other galaxy like our own, shining across the vastness of intergalactic space. Light from the Andromeda galaxy has traveled so far that it’s taken more than 2 million years to reach us. Two smaller companions visible through binoculars on a dark, transparent night are the Andromeda galaxy’s version of our Milky Way’s Magellanic Clouds. These small, orbiting, irregularly-shaped galaxies will eventually be torn apart by their parent galaxy’s gravity.

Such sights, from lunar wastelands to the glow of a nearby island universe, are all within reach of a pair of handheld optics, really small telescopes in their own right: your binoculars.

John Shibley wrote the original draft of this article, years ago, and we’ve been expanding it and updating it ever since. Thanks, John!

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Bottom line: For beginning stargazers, there’s no better tool than an ordinary pair of binoculars. This post tells you why, and gives you a rundown on some of the coolest binocular sights out there: the moon, the planets, inside the Milky Way, and beyond.

Source:
https://earthsky.org/human-world/top-tips-for-using-ordinary-binoculars-for-stargazing

Jupiter officially has 12 new moons, discovered in 2018. They are outer moons; their orbits are shown here. Image via Carnegie Science.

The Carnegie Institution for Science – headquartered in Washington, D.C. – announced in late August that the winners of its Jupiter-moon-naming contest have been selected. From February to April, this institution had solicited name suggestions for five of the 12 moons of Jupiter discovered in 2018 by a team led by Carnegie’s Scott S. Sheppard.

Sheppard commented:

I was blown away by the enthusiastic response for this contest. I hope the thought of these moons let everyone ponder the wonder and amazement that is our universe.

Astronomer Scott Sheppard of Carnegie Science led a team that discovered 12 new moons for Jupiter in 2018. Now 5 of those new moons have been given new names. Image via Carnegie Science. Visit Scott Sheppard’s Jupiter-moons page.

He added that there are many rules in place – regulated by the International Astronomical Union (IAU) – when it comes to naming new moons:

Most notably, Jovian naming conventions require its many moons to be named after characters from Greek and Roman mythology who were either descendants or consorts of Zeus, or Jupiter.

And there are other strictures as well, including a maximum character length and the final letter of each name, depending on the direction of a moon’s orbit. Carnegie Science combed through people’s suggestions and sent what they felt were the best-suited names to the IAU, which published the final names on August 23, 2019. Here they are:

S/2017 J4 is now Pandia. Carnegie Science said:

She is the daughter of Zeus and the Moon goddess Selene. Pandia is the goddess of the full moon and the sister of Ersa. The name Pandia was one of the more popular names entered into the contest. Our favorite submission was representing the astronomy club of the Lanivet School in Cornwall, England. Emma Hugo (@emmabray182) tweeted a picture of the astro club with a Pandia sign and the school’s Panda mascot, which is in honor of the village’s former role as bamboo supplier to the London zoo.

#NameJupitersMoons Pandia!! daughter of Zeus and Selene, goddess of moon's.
Also our schools logo/mascot is a panda, very similar name. The Astro club chose this name! Our village used to provide London zoo with bamboo for the pandas that lived there. pic.twitter.com/wR0940PHNc

— emma hugo (@emmabray182) March 20, 2019

https://platform.twitter.com/widgets.js

S/2018 J1 is now Ersa. Carnegie Science said:

She is the sister of Pandia and, as such, also the daughter of Zeus and the Moon goddess Selene. Ersa is the goddess of dew. There were more than 20 tweets suggesting the name Ersa. Being the daughter of a Moon goddess seemed very appropriate for a Jovian moon. The first submission was from space news aggregator Aaron Quah (@8603103) and the submissions that most caught our eye about Ersa were submitted by the 12th grade students of Saint Sauveur High School in Redon, France (@StSauMoons), on behalf of the fifth grade at Hillside Traditional Academy in Mission, British Columbia (@mrgrouchypants), and on behalf of a 4-year-old lunar expert Walter who sang us a moon song (@Thoreson).

@JupiterLunacy Our 4-year-old resident moon expert Walter would like to submit 3 name options for Jupiter's new moons: Selene (Greek goddess of the moon and lover of Jupiter/Zeus) and their daughters Pandeia and Ersa. #NameJupitersMoons https://t.co/2YG2Q85Dyz

— Lindsey Hansen (@Thoreson) April 15, 2019

https://platform.twitter.com/widgets.js

S/2003 J5 is now Eirene. Carnegie Science said:

She is the goddess of peace and the daughter of Zeus and Themis. About 16 tweets suggested naming a Jupiter moon Eirene. The first submission was from Quadrupoltensor (@Quadrupoltensor), and the entry for Eirene that caught our eye (@PJRYYC) was submitted on behalf of a 10-year-old who loves Greek and Roman mythology.

S/2003 J15 is now Philophrosyne. Carnegie Science said:

She is the spirit of welcome and kindness and is the granddaughter of Zeus and sister of Eupheme. Winning submissions were from an 11th grade history class with a proclaimed interest in Greek and Roman mythology, CHW3M Myth Experts (@Chw3mmyths); Victoria (@CharmedScribe); and Lunartic (@iamalunartic), an account dedicated to moons, which posted several videos about the contest, including one that evaluated this suggestion.

S/2003 J3 is now Eupheme. Carnegie Science said:

She is the spirit of praise and good omen, the granddaughter of Zeus, and the sister of Philophrosyne. Winning submission was from the same video by Lunartic (@iamalunartic).

Bottom line: The Carnegie Institution of Science has announced new names for 5 of Jupiter’s newly discovered moons.

Via Carnegie Science

Source:
https://earthsky.org/space/new-names-5-jupiter-moons-contest-winners