Write a for-and-against essay about the advantages and disadvantages of teenagers using mobile phones for your English teacher (80-90 words). ⚫ Para 1 (Introduction):
⚫ most teenagers have mobile phones
⚫ Para 2 (Advantages):
⚫ learn from educational sites
⚫ take a break from studying
⚫ Para 3 (Disadvantages):
⚫ Can be harmful
⚫ don’t do sport or hobby
⚫ Para 4 (Conclusion):
⚫ All in all, mobile phones are useful gadgets to have. However….
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ответ:
объяснение:
astronomers study our own solar system, as well as other solar systems, stars, and galaxies. the bulk of an astronomer's job is heavily based on research, as the focus is on understanding how the universe works, and on trying to discover things about the universe that would be considered scientific breakthroughs.
the main tools used by astronomers are:
telescopes - used to gather light emissions
spectrographs - used to break up light into a spectrum to tell the temperature, composition, and velocity of space objects
cameras - are connected to telescopes and used to gather images
spacecrafts - cameras and telescopes are placed onboard to collect images of space objects
computers - used to analyze data received from telescopes and spacecraft
astronomers use all these tools quite often, especially telescopes (along with applying a lot of physics and mathematics). they are able to use a variety of telescopes to observe objects in the universe - some of these telescopes are located here on planet earth and some are sent into space. only the very closest planets (all within our solar system) can be reached by spacecraft. therefore, telescopes or earth-orbiting satellites are relied upon to indirectly give us information about all other celestial objects by observing light emitted or reflected from them. telescopes gather light from distant objects and let us see them "up close." it is through the collection and detailed analysis of this light that astronomers are able to unlock some of the many mysteries of the universe. if fact, the main purpose of using a telescope is to collect this light so the astronomer can analyze and interpret this data.
an example of a telescope astronomers use is the hubble space telescope. it can see out to a distance of several billions of light-years (a light-year is the distance that light travels in one year, about 5,865,696,000,000 miles). the farthest that the hubble space telescope has seen so far is about 10-15 billion light-years away. several of the hubble deep field galaxies that astronomers are able to see are as they were billions of years ago, because this is how long it took for their light to reach us.
there are different fields of astronomy, and most astronomers will choose to focus on only one. some examples of these fields are solar astronomy, planetary astronomy, stellar astronomy, galactic astronomy, extragalactic astronomy, and cosmology. each field then branches into an observational or theoretical type of study. the observational branch uses the basic principles of physics and is focused on acquiring and analyzing data. the theoretical branch, on the other hand, describes astronomical objects and phenomena through the development of computer or analytical models. the two branches go hand-in-hand, with theoretical astronomy focusing on explaining the observational results, and observational astronomy being used to confirm theoretical results.
astronomy can also be divided according to its links with other branches of science, as it can apply physics, biology and geology to explain the origin and evolution of space, stars and celestial bodies. those four sub-fields are: astrophysics, astrometry, astrogeology, and astrobiology.