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Time
This category is for questions about the methods humans go about measuring the passage of time. You can also find questions about converting one unit of time to another.
9,512 Questions
What would happen in 1000 years from now?
It is difficult to predict with certainty what will happen in 1000 years from now, as many variables can influence the future. However, it is likely that technology will have advanced significantly, societies may be more interconnected, and there may be new challenges and opportunities that we cannot imagine today. Environmental changes and how they are addressed will also play a crucial role in shaping the future.
We have days and nights on earth due to the Earth rotating around axis. Approximately over 23.6 hours our Earth makes one complete rotation and as we rotate, we rotate away from the sun (night) and back towards it (day). A sundial works by gauging the suns position in the sky relative to where we are in that 24 hour period. The sun casts shadows on the sundial in different places as it moves across our sky, indicating different times. The time piece on the sundial is called a "gnomon" and by reading where the shadow falls when the sun hits the gnomon we can estimate the time of day.
Why are there 24 hours in a day?
The dividing of the day into useful chunks of time goes back to our earliest recorded history, and probably through pre-history as well. People in many cultures were of course aware of the regular passage of the sun across the sky, and most realized that the sun follows an arc-like line. The sun reaches a 'highest' point at mid-day and this could be used, along with sunrise and sunset, to begin charting out time periods of various length. They also noticed and studied the movements of the stars as they moved during the night, and as they changed over the year. In our earliest days we certainly didn't need anything nearly as accurate as a second or minute for daily activities, but many cultures had sophisticated ways to mark out some of the basic movements of the sun with great accuracy. The history is long and interesting and you can check the link as a starting point.
There is nothing magical or innately 'physical' about the idea of 24 equal time segments for a day, although this turns out to be a very useful number. We arrived at it over a long period of time, and essentially by convention. Often the ancient Egyptians are credited with getting the system going. There were number systems based on 12 at the time. The significance of the number 12 is mostly due to the 12 lunar cycles in a year and can also be found in other ancient civilizations in China, India and Sumer.
This may be why these systems often started by breaking the daylight period into 12 segments. Breaking the night time up in a similar way was an easy step. It would be impossible to highlight all the subtle quirks involved in our measurement of time, but here are some of them.
The modern 24 hour day is really a rather artificial system; a day measured this way in Universal Time does not match up to a solar day, a day that you would measure from 'solar noon' to 'solar noon'.
The length of a second (and by extension, an hour) is an average, or mean calculation originally based on the length of an entire year. This is why Universal Time was once called Greenwich Mean Time. This is also why Universal Time does not perfectly match the sun's movements. A second is now defined very precisely as a certain number of oscillations of a cesium atom. This definition may hold for many centuries and is now essentially independent of the earth's movement.
Our measurements of time seem to be so regular and absolute, yet as you know we need to add a day to our year to keep our calendars in synch with our yearly revolution around the sun.
What you may not know is that from time to time we need to add a leap second to a year (this is rarely made known to the public-- we really don't need to know. But people who are responsible for communications systems, etc. are made aware of it.) The whole topic is very complex and not particularly easy to grasp. It is a great study for those interested.
Is midnight 12 hours before or after noon on that same day?
Midnight always occurs 12 hours before noon of that same day.
I suspect, however, what you are really asking is Does 12:00 midnight begin a day or end a day? Let me explain it this way: Let's say that your teacher tells you that you must hand in your term paper by midnight Wednesday. Must you hand it in at 12:00 midnight as Tuesday turns to Wednesday or as Wednesday turns to Thursday? It is generally accepted that "midnight Wednesday" occurs AFTER the 24 hours of Wednesday have elapsed. So if your teacher rejects your paper that you plopped on his desk at, say, 9:00am on Wednesday because he says it was due by midnight, tell him you're 15 hours early. Which segues nicely into a pet peeve of mine: 12:00am and 12:00pm. Talk about ambiguous! There is no such thing as either one of those times. It's either 12:00 noon or 12:00 midnight. Having said that, though, most people think of 12:00am as midnight. Most, not all.
In military time, 12:00 midnight is 00:00 (for those of you that do not know military time, P.M. hours are 13:00-23:00, rather than 1:00pm-11:00pm; A.M. hours are 00:00-12:00, rather than 12 midnight-12 noon). Therefore, using military time, 12:00 midnight would be the beginning of the day. However, as there is no clear line between, the answer above can also be correct. If you're facing a deadline or in another situation where knowing the exact time is important, ask for a specification if possible.
Why is uplift and erosion over a long period of time destroy a part of the rock record?
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How are eras and periods of the geologic time scale named?
Eras and periods on the geologic time scale are often named based on significant geological events, key fossil groups, or regional stratigraphy that characterize that time interval. For example, the Triassic Period is named after the three distinct rock layers found in Germany. The Cretaceous Period is named after the Latin word "creta," meaning chalk, due to the abundant chalk deposits from this time.
How can ice cores be used to tell us how earths climate has changed over time?
Ice cores contain valuable information such as air bubbles and isotopic composition that can be used to reconstruct past climate conditions like temperature and atmospheric composition. By analyzing the layers of ice cores, scientists can track changes in these parameters over time and gain insights into how Earth's climate has evolved.
What is a measurements of earth's history divided into time periods?
fossil record
geologic time scale
You are lava. Lava is molten rock that flows as a liquid when hot and solidifies to form mountains when cooled. It can erupt from volcanoes to destroy towns and often resides underground in magma chambers.
What happens to the total amount of water on earth over time?
The total amount of water on Earth remains relatively constant through the water cycle, where water evaporates from oceans and other bodies of water, condenses into clouds, and falls back to the surface as precipitation. However, changes in climate and human activities can affect the distribution and availability of water in different regions.
Which events takes the most time revolutioning of earth?
The revolution of Earth around the Sun takes the most time, completing one orbit in about 365.25 days. This revolution is what defines a year on Earth.
What is the Order the units or geologic time from the longest to the shortest?
The order of units of geologic time from longest to shortest is: eon, era, period, epoch.
Paleontologists, stratigraphers, and geochronologists worked with geologists to develop the geologic time scale. Paleontologists studied fossil evidence, stratigraphers looked at the layers of rock formations, and geochronologists used radiometric dating techniques to determine the age of rocks and fossils.
Is an example of an Earth process being used to measure geologic time?
One example is radiometric dating, which uses the decay of radioactive isotopes in rocks to determine their age and establish a timeline of Earth's geological history. By analyzing the ratio of parent and daughter isotopes in a sample, scientists can calculate the age of the rock and infer when certain geological events occurred.
What are the variable gases by the time or location season?
Variable gases in the atmosphere include water vapor, carbon dioxide, methane, ozone, and nitrous oxide. Their concentrations can vary by location and season due to factors such as human activities, natural processes, and weather patterns influencing their production and removal rates.
The super-continent proposed by the theory of continental drift is called Pangaea. It is believed to have existed about 300 million years ago and subsequently broke apart to form the continents as we know them today.
Continued petroleum extraction can deplete petroleum resources in selected areas over time, leading to lower availability and potentially driving up prices. It can also contribute to environmental issues such as habitat destruction, air and water pollution, and greenhouse gas emissions that can impact ecosystems and human health. Additionally, the extraction process can release methane, a potent greenhouse gas, contributing to climate change.
Summer, Autumn, Winter and spring are the results.
How do scientists know how oxygen levels have changed over deep time?
Scientists use geological records such as rock formations, ice cores, and ocean sediments to measure oxygen isotope ratios. Changes in these ratios over time can provide insights into past oxygen levels. Additionally, the presence of certain fossils and chemical markers in rocks can also indicate past variations in atmospheric oxygen.
What does the geologic time scle indicate about the change in life-forms over time?
The geologic time scale shows the chronological arrangement of Earth's history based on significant events and changes in life-forms over time. It indicates the evolution and diversity of life on Earth, as well as the occurrence of mass extinctions and the emergence of new species. By studying the fossil record and the time scale, scientists can understand how life-forms have evolved and adapted to different environments over millions of years.
There is often a short amount of time to evacuate before an earthquake because earthquakes can occur suddenly without warning. Providing accurate early warnings can be challenging due to the unpredictable nature of seismic events. Quick evacuation protocols are in place to mitigate the risk of injury or harm to individuals in the affected area.
What are Three great time bombs in earths future are?
Three great time bombs in Earth's future are climate change, continued destruction of natural habitats, and depletion of essential resources like water and minerals. These issues have the potential to significantly impact ecosystems, species extinction, and human well-being if not addressed urgently.
What are Different ways land and things are changed over time?
Land and things can change over time through natural processes like erosion, weathering, and sedimentation. Human activities, such as agriculture, deforestation, urbanization, and mining, can also significantly alter land and its features over time. Additionally, factors like climate change can accelerate these changes and impact the overall ecosystem.
