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marino5856

hour (unit of time) -- Encyclopedia Britannica - 0 views

  • in timekeeping
  • 3,600 seconds, now defined in terms of radiation emitted from atoms of the element cesium under specified conditions. The hour was formerly defined as the 24th part of a mean solar day—i.e., of the average period of rotation of the Earth relative to the Sun. The hour of sidereal time, 1/24 of the Earth’s rotation period relative to the stars, was about 10 seconds shorter than the hour of mean solar time.
    • marino5856
       
      It also has 24 hours the earth because in the system of the egyptians it said that it also has 24 hours because of the earth spinning.
  • In even earlier systems of timekeeping, an hour was 1/12 of a period of daylight or darkness—hence, variable in length with seasonal changes in the length of day and night. The custom of dividing the cycle of day and night into 24 periods seems to have originated with the ancient Egyptians.
touche5839

Sleepwalking -- Britannica School - 0 views

    • touche5839
       
      Sleepwalking is when people are in there sleep and they get out of bed. The person can walk, talk, or just sit on the bed. This mostly happens when children are in a very deep sleep. It's only dangerous if the sleepwalker becomes hurt.
marino5856

Clocks - How Time Works - 1 views

  • A day consists of two 12-hour periods, for a total of 24 hours. An hour consists of 60 minutes. A minute consists of 60 seconds. Seconds are subdivided on a decimal system into things like "hundredths of a second" or "millionths of a second."
    • marino5856
       
      There is 24 hours in a day because  they first divided 60 and that equals 12. So 12 plus 12 equals 24 so thats how they had 24 hours in a day.
  • hat's a pretty bizarre way to divide a day up. We divide it in half, then divide the halves by twelfths, then divide the twelfths into sixtieths, then divide by 60 again, and then convert to a decimal system for the smallest increments. It's no wonder children have trouble learning how to tell time.
  • How long is a day? It's the amount of time it takes for the Earth to rotate one time on its axis. But how long does it take the Earth to rotate? That is where things become completely arbitrary. The world has decided to standardize on the following increments:
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  • Why are there 24 hours in a day? No one really knows. However, the tradition goes back a long way. Take, for example, this quote from Encyclopedia Britannica:
  • Why are there 60 minutes in an hour and 60 seconds in a minute? Again, it is unclear. It is known, however, that Egyptians once used a calendar that had 12 30-day months, giving them 360 days. This is believed to be the reason why we now divide circles into 360 degrees. Dividing 360 by 6 gives you 60, and 60 is also a base number in the Babylonian math system.
    • marino5856
       
      The Egyptians had a calendar that has 12 months so that equals 360 day in total. Also science they new that there is 360 days in a year thats why a circle is 360 degrees. The Roman people invented that so that in the clock there is not 24 hours in a clock so there is 12 am and 12pm.
  • What do a.m. and p.m. mean? These abbreviations stand for ante meridiem, before midday, and post meridiem, after midday, and they are a Roman invention. According to Daniel Boorstin in his book The Discoverers, this simple division of the day into two parts was the Romans' first increment of time within a day:
Regina Cantu

Bartolomeu Dias -- Encyclopedia Britannica - 0 views

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    Bartholomew Dias Info
Diego Hinojosa

Venus -- Britannica School - 0 views

  • The second planet from the Sun is Venus. After the Moon, Venus is the most brilliant natural object in the nighttime sky. It is the closest planet to Earth, and it is also the most similar to Earth in size, mass, volume, and density. These similarities suggest that the two planets may have had similar histories. Scientists are thus intrigued by the question of why Venus and Earth are now so different.
    • Diego Hinojosa
       
      Venus is the second closest planet to the sun.It is really similar to earth and also it is the planet most close to earth. The earth and venus are really similar on size and also atmosphere.
Esteban Cantu

Jupiter -- Britannica School - 0 views

  • The planet is one of the brightest objects in the night sky, and even a small telescope can reveal its multicolored stripes. These stripes are bands of clouds being pushed around the planet by strong east-west winds. Jupiter is a world of complex weather patterns. Its most prominent feature is an orange-red oval called the Great Red Spot. The oval is a storm system that has lasted at least 300 years and is bigger across than Earth and Mars combined.
    • Esteban Cantu
       
      Jupiter is a really bright planet. Even with a small telescope, you can see it's stripes in the night sky. The great red spot is a giant storm. Scientist believe it's lasted 300 years long.
Diego Hinojosa

Neptune -- Britannica School - 0 views

  • The planet that Voyager uncovered is a stormy, windswept world with a vivid blue hue. Its highly active atmosphere is surprising, since it receives so little sunlight to power its weather systems. Like the other giant outer planets, Neptune has no solid surface. It also has a system of rings and more than a dozen moons.
    • Diego Hinojosa
       
      Neptune is a planet that has a lot of blue. It's atmosphere and also surface is not solid. It also has rings and like 12 moons.
  • Neptune is the smallest of the four giant outer planets. The diameter at its equator is about 30,775 miles (49,528 kilometers), as measured at a level of the atmosphere where the pressure is 1 bar (the pressure at sea level on Earth). This makes it slightly smaller than Uranus but nearly four times as big as Earth. Neptune’s mass is about 1.2 times greater than Uranus’, however, and more than 17 times greater than Earth’s. It is the third most massive planet in the solar system, after Jupiter and Saturn. Like the other outer planets, Neptune has a low density—only about 1.6 times the density of water. However, it is the densest of the four, being roughly 25 percent denser than Uranus.
    • Diego Hinojosa
       
      Neptune is also the smallest planet of the biggest four. The atmosphere of neptune is really thick.Neptune is the most hard planet in other words solid planet and it is four times bigger than the earth.
Diego Hinojosa

Mars -- Britannica School - 0 views

  • Nevertheless, the search for life on Mars continues, in part because it shows signs of having been wetter in the past. Water is necessary for all known forms of life. It is possible that microscopic life once existed on Mars. Today the surface is too cold and the air is too thin for liquid water to exist there for long. It is also bombarded with ultraviolet radiation from the Sun, which is very harmful to living things.
    • Diego Hinojosa
       
      Mars is the fourth planet from the sun for years and years there have been sending  little robots and machines from NASA to find more information. It has a very little atmosphere to protect it from the sun.
Diego Hinojosa

Saturn -- Britannica School - 0 views

  • Saturn was named after the ancient Roman god of agriculture. His counterpart in ancient Greek mythology was Cronus, the father of Zeus (the counterpart of the Roman god Jupiter). The planet Jupiter is Saturn’s nearest neighbor and the closest to it in size and composition. Like Jupiter, Saturn is a giant world formed mainly of hydrogen with no solid surface. It has a massive atmosphere, or surrounding layer of gases, with complex weather patterns. ESA/NASA/JPL/University of ArizonaESA/NASA/JPL/University of Arizona The planet’s extensive system of icy moons includes nine major moons and dozens of small ones. Some of the moons help create the rings and maintain their shape. Titan, the largest of Saturn’s moons, is bigger than the planet Mercury. It is the only moon in the solar system known to have a dense atmosphere.
    • Diego Hinojosa
       
      Saturn is the planet that has a lot of similarities to jupiter it dosen't have a solid surface. I't, with jupiter are the only planet with no solid surface it has a very harsh atmosphere.
    • Diego Hinojosa
       
      Saturn has a lot of similarities with Jupiter.They both don't have a solid surface they are both made of no more than oxygen etc. It has a massive and harsh atmosphere and it is the biggest planet with jupiter. Saturn has rings inside of the rings it has a mixture of things like sand and other materials.
Diego Hinojosa

Uranus -- Britannica School - 0 views

  • Uranus is the third largest planet in the solar system, after Jupiter and Saturn. Uranus is about four times bigger than Earth. Its diameter at the equator is about 31,763 miles (51,118 kilometers), as measured at the level of the atmosphere where the pressure is the same as at sea level on Earth. The planet is slightly larger than Neptune, but Neptune is about 1.2 times more massive. Uranus’ density is quite low—only about 1.3 times that of water, compared with 1.6 for Neptune and 5.5 for rocky Earth.
    • Diego Hinojosa
       
      Uranus is the third biggest planet on the whole solar system it is four times bigger than earth and it has a ver massive atmosphere
    • Diego Hinojosa
       
      Uranus is one of the 3 other planets that is the biggest on the whole solar system.It has a very harsh atmosphere.And it has very little water.
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