A Hidden Ocean Might Exist Under Ganymedes Icy Surface

A Hidden Ocean Might Exist Under Ganymede's Icy Surface When you think about the Jupiter system, you think of a gas giant planet. It has major storms whirling around in the upper atmosphere. Deep inside, its a tiny rocky world surrounded by layers of liquid metallic hydrogen. It also has strong magnetic and gravitational fields that could be obstacles for any kind human exploration. In other words, an alien place.   Jupiter just doesnt seem like the kind of place that would also have tiny water-rich worlds orbiting around it.   Yet, for at least two decades, astronomers have suspected that the tiny moon Europa had subsurface oceans. They also think that  Ganymede has at least one (or more) oceans as well.  Now, they have strong evidence for a deep saline ocean there. If it turns out to be real, this salty subsurface sea could have more than all the water on Earths surface. Discovering Hidden Oceans How do astronomers know about this ocean? The latest findings were made using the Hubble Space Telescope to study Ganymede. It has an icy crust and a rocky core. What lies between that crust and core have intrigued astronomers for a long time. This is the only moon in the entire solar system that is known to have its own magnetic field. Its also the largest moon in the solar system. Ganymede also has an ionosphere, which is lit up by magnetic storms called aurorae. These are mainly detectable in ultraviolet light.   Because aurorae are controlled by the moons magnetic field (plus the action of Jupiters field), astronomers came up with a way to use the motions of the field to look deep inside Ganymede. (Earth also has aurorae, called informally the northern and southern lights).   Ganymede orbits its parent planet embedded in Jupiters magnetic field. As Jupiters magnetic field changes, the Ganymedean aurora also rock back and forth. By watching the rocking motion of the aurorae, astronomers were able to figure out that theres a large amount of salt water beneath the crust of the moon.The saline-rich water suppresses some of the influence that Jupiters magnetic field has on Ganymede, and that is reflected in the motion of the aurorae.   Based on Hubble data and other observations, scientists estimate the ocean is 60 miles (100 kilometers) deep. Thats about ten times deeper than Earths oceans. It lies under an icy crust thats about 85 miles thick (150 kilometers). Beginning in the 1970s, planetary scientists suspected the moon might have a magnetic field, but they didnt have a good way to confirm its existence. They finally got information about it when the  Galileo spacecraft took brief snapshot measurements of  the magnetic field in 20-minute intervals. Its observations were too  brief to distinctly catch the cyclical rocking of the oceans secondary  magnetic field. The new observations could only be  accomplished with a space telescope high above Earths atmosphere, which  blocks most ultraviolet light. The Hubble  Space Telescope Imaging Spectrograph, which is sensitive to ultraviolet light given off by the auroral activity on Ganymede, studied the aurorae in great detail.    Ganymede was discovered in 1610 by astronomer Galileo Galilei. He spotted it in January of that year, along with three other moons: Io, Europa, and Callisto. Ganymede was first imaged up-close by the Voyager 1 spacecraft in 1979, followed by a visit from Voyager 2 later that year.  Since that time, it has been studied by the Galileo and New Horizons missions, as well as Hubble Space Telescope and many ground-based observatories.The search for water on worlds such as Ganymede is part of a larger exploration of worlds in the solar system that could be hospitable to life.   There are now several worlds, besides Earth, that could (or are confirmed) to have water: Europa, Mars, and Enceladus (orbiting Saturn). In addition, the dwarf planet Ceres is thought to have a subsurface ocean.

5 Erroneously Constructed Not Only . . . But Also Sentences

5 Erroneously Constructed Not Only . . . But Also Sentences 5 Erroneously Constructed â€Å"Not Only . . . But Also† Sentences 5 Erroneously Constructed â€Å"Not Only . . . But Also† Sentences By Mark Nichol Writers often have difficulty determining the word order in sentences in which the phrase â€Å"not only† appears followed by an example and then, subsequent to â€Å"but also,† another example. Here are fixes to five such sentences. 1. â€Å"Digital cameras are not only changing photography, but our lives.† The key to correct syntax in â€Å"not only . . . but also† constructions is, when sharing a verb between the two examples, placing â€Å"not only† after the verb: â€Å"Digital cameras are changing not only photography but also our lives.† 2. â€Å"He wasn’t only listening to tone, but also to the rhythms and patterns he would need to understand and communicate.† This sentences partially conceals the problem because not is part of a contraction. To solve it, spell out the contracted phrase, and follow the rule stated in the explanation of the example above: â€Å"He was listening not only to tone but also to the rhythms and patterns he would need to understand and communicate.† 3. â€Å"Many people prefer the squatter neighborhoods not only because they provide affordable housing but freedom from government control and a sense of community spirit.† This sentence is improved by the basic strategy of placing the verb before â€Å"not only,† but a further fix is recommended. Because the element following â€Å"but also† is a two-part phrase, freedom may be (at least initially) misconstrued as applying to both â€Å"government control† and â€Å"a sense of community spirit,† so distance the second phrase from the first: â€Å"Many people prefer the squatter neighborhoods because they provide not only affordable housing but also freedom from government control, as well as a sense of community spirit.† 4. â€Å"We house them in the nicest neighborhoods we can afford, the ones that are not only comfortable in themselves, but that mask direct evidence of the world’s unfairness.† In this example, each corresponding phrase has its own verb. When this is the case, simply place â€Å"not only† and â€Å"but also† immediately preceding the respective verbs: â€Å"We house them in the nicest neighborhoods we can afford, the ones that not only are comfortable in themselves but also mask direct evidence of the world’s unfairness.† 5. â€Å"Eventually, I began to notice that dreams are not only inspirations for creative life and interesting puzzles to be solved, but that they provided access to a world of meaning that was even greater than the tactics of nonviolent social change.† More complex sentences pose a challenge, but as in the other examples, simply break the sentence elements down. The two points of this sentence are â€Å"dreams are inspirations . . .† and â€Å"they provide access . . . .† To achieve parallel structure, precede the first phrase with â€Å"not only that† and the second one with â€Å"but also that†: â€Å"Eventually, I began to notice not only that dreams are inspirations for creative life and interesting puzzles to be solved but also that they provide access to a world of meaning that was even greater than the tactics of nonviolent social change.† Want to improve your English in five minutes a day? Get a subscription and start receiving our writing tips and exercises daily! Keep learning! Browse the Grammar category, check our popular posts, or choose a related post below:Writing a Reference Letter (With Examples)Cannot or Can Not?When to Spell Out Numbers