Nearly 500 million miles from the Sun lies a moon orbiting Jupiter that is slightly larger than the planet Mercury and may contain more water than all of Earth's oceans. Temperatures are so cold, though, that water on the surface freezes as hard as rock and the ocean lies roughly 100 miles below the crust. Nevertheless, where there is water there could be life as we know it. Identifying liquid water on other worlds — big or small — is crucial in the search for habitable planets beyond Earth. Though the presence of an ocean on Ganymede has been long predicted based on theoretical models, NASA's Hubble Space Telescope found the best evidence for it. Hubble was used to watch aurorae glowing above the moon's icy surface. The aurorae are tied to the moon's magnetic field, which descends right down to the core of Ganymede. A saline ocean would influence the dynamics of the magnetic field as it interacts with Jupiter's own immense magnetic field, which engulfs Ganymede. Because telescopes can't look inside planets or moons, tracing the magnetic field through aurorae is a unique way to probe the interior of another world.
Join Hubble astronomers during a live Hubble Hangout discussion about Ganymede at 3pm EDT on Thurs., March 12, to learn even more. Visit http://hbbl.us/y6f .
Planetary science: Frozen in darkness
Nature 540, 7634 (2016). doi:10.1038/nature21108
Author: Luca Maltagliati
In 2014, water vapour was detected around Ceres, a dwarf planet in the asteroid belt. NASA's Dawn spacecraft, in orbit around Ceres since March 2015, subsequently found water ice on the dwarf planet, in a small, mid-latitude crater named Oxo. Now, writing in Nature Astronomy
Planetary science: Where Ceres hides its water
Nature 540, 7634 (2016). doi:10.1038/540487e
Frozen water has been lurking beneath the rocky surface of the Solar System's biggest asteroid since its birth billions of years ago.NASA's Dawn spacecraft began orbiting Ceres (pictured), which is also a dwarf planet, in 2015. This allowed a team led by
Two glowing nebulas in the Small Magellanic Cloud, a dwarf galaxy that is a satellite of our Milky Way galaxy, have been observed by NASA's Hubble Space Telescope. Young, brilliant stars at the center of each nebula are heating hydrogen, causing these clouds of gas and dust to glow red. The image is part of a study called Small Magellanic Cloud Investigation of Dust and Gas Evolution (SMIDGE). Astronomers are using Hubble to probe the Milky Way satellite to understand how dust is different in galaxies that have a far lower supply of heavy elements needed to create dust.
Data from the world's largest digital sky survey is being publicly released today by the Space Telescope Science Institute (STScI) in Baltimore, Maryland, in conjunction with the University of Hawaii Institute for Astronomy in Honolulu, Hawaii. Data from the Pan-STARRS1 Surveys will allow anyone to access millions of images and use the database and catalogs containing precision measurements of billions of stars and galaxies. The four years of data comprise 3 billion separate sources, including stars, galaxies, and various other objects. The immense collection contains 2 petabytes of data, which is equivalent to one billion selfies, or one hundred times the total content of Wikipedia.
The trial in which the famous astronomer, Johannes Kepler, defended his mother from accusations of witchcraft has been turned into an opera, following new research into the original 17th-century legal proceedings.
The opera was conceived by Cambridge historian Professor Ulinka Rublack, a fellow of St John’s College. It made its debut in October as part of Cambridge University’s Festival of Ideas. A film of Kepler’s Trial: An Opera is now available online.
Born in 1571, Johannes Kepler is one of the most admired astronomers who ever lived. He came from an ordinary family but became a major figure in the scientific revolution. He defended Copernicus’s idea that the sun was at the centre of the universe and defined three laws of planetary motion.
In 1615, at the height of his powers, Kepler abandoned his research to defend his elderly mother, Katharina, from charges of witchcraft. Her trial took place at the height of Europe’s infamous ‘witch-craze’. Thousands of people, mostly women, were executed for supposed dealings in the occult, and families were torn apart in a climate of paranoia and distrust.
The new opera tells the remarkable tale of Katharina’s six-year ordeal, and her son’s dogged, and ultimately successful, defence. Rublack’s recent book, The Astronomer and the Witch, is the first to provide a full account of the case.
It is not the first time that aspects of Johannes Kepler’s life have been given the operatic treatment. Philip Glass’s Kepler focused on the astronomer’s life and work, but overlooked the trial completely. In 1957, the German composer, Paul Hindemith, composed Die Harmonie der Welt (Harmony Of The World, also the title of one of Kepler’s most famous works.)
Like many other accounts of Kepler’s story, which either unwittingly swallow the 17th-century prosecution’s character assassination of Katharina, or reproduce it for dramatic effect, these treatments presented Kepler’s mother as crazed and witchlike.
Rublack sees the most recent opera as a response, in particular, to Hindemith’s work. “When I finished the book, I thought, there really has got to be a new opera about the subject now,” she said. “Hindemith depicts Katharina as a crazed, old crone. I wanted to put together a team to develop new perspectives and create a new way to tell the story.”
Kepler's Trial: An Opera draws on Rublack's research with supporting contributions from a group of interdisciplinary scholars and academics. The libretto was written by Tim Watts, a composer who teaches music at St John’s College and lectures in the University’s Faculty of Music.
The performance features video sequences by the artist Aura Satz, who is based at the Royal College of Art. The videos are designed to amplify its presiding themes: darkness and light, sight and illusion, and competing depictions of an ageing and vulnerable woman.
“Around 25,000 people were executed for witchcraft in the 16th and 17th centuries,” Rublack said. “When Katharina was accused in 1615, she was actually at a point in her life when things were going very well. The accusation came as completely unexpected for her and the family, and turned into something profoundly disturbing.”
Although she was ultimately acquitted thanks to her son’s defence (as well as helpful connections in the upper echelons of the justice system), the trial had devastating consequences. Katharina was disowned by two of her other children and spent 14 months of the trial period living in a prison cell, chained to the floor. She emerged both physically and emotionally exhausted, and died just six months later.
The opera makes use of musical styles from the time, drawing inspiration from the likes of Claudio Monteverdi as well as found materials such as contemporary drinking songs. It is performed using instruments that would have been popular during the period, such as cornets, sackbuts, and harpsichord.
The premiere took place in the atmospheric surroundings of the Chapel of St John’s College. The six violinists playing at the event were all from St John's; they included the College's Musician-in-Residence, Margaret Faultless, as well as five students.
The trial papers are still preserved in regional archives in Stuttgart. The libretto draws on the actual words of both Katharina and Johannes Kepler as they were recorded in court. Fragments of Katharina’s voice come through in prayers and her response to cross-examination, taken from the transcripts.
“It’s been easier to invent a voice for Katharina than it has been to define one for her son,” Watts reflected. “So many of his words exist already and we know a large amount about the kind of man he was, so there’s a lot more to filter.”
“The way that we tell the story offers a huge range for potential identification with characters and elements. There is a sense of worlds and generations colliding; it’s my hope that the piece involves such a range of character and generation that it will appeal to an equally wide range of people.”
An ambitious opera, telling the story of an infamous witch trial, was premiered in October. A film of Kepler's Trial the Opera is now available online. The project was conceived by historian Professor Ulinka Rublack whose recent research shines new light on a 400-year-old scandal.
YesRelated Links: Kepler's Trial: An OperaBBC Radio 4 In Our Time
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