Earth's Sunset (NASA, International Space Station Science, 04/26/08)

Sunset Calculation

Posted by AT
Knowing the earth rotation and revolution correctly makes it possible to calculate the time and angle of sunset precisely for any location on Earth as we did with sunrise. We should be aware that there are areas near the poles where the sun remains visible or invisible the whole day.…
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silhouette of newly wedded couple

Sun Rise Calculations

Posted by AT
Knowing the earth rotation and revolution correctly makes it possible to calculate the time and angle of sunrise precisely for any location on Earth. We should be aware that there are areas near the poles where the sun remains visible or invisible the whole day. We can calculate sunrise from…
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Solar Scientist Confirm Existence of Flux Ropes on the Sun

Sun Distance

Posted by AT
Sun distance from earth ranges from 147 million kms to 152 Million kms. Sun distance depends on the time of the year and it is less in winter and more in Summer. The following web app gives this value for any day during the year: Year Sun Distance Today :…
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The Tolsey Clock

Equation of Time

Posted by AT
Equation of time is the difference between apparent solar time and mean solar time. EOT = apparent solar time – mean solar time Wikipedia defines EOT by the follwoing: The equation of time describes the discrepancy between two kinds of solar time. The word equation is used in the medieval…
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Magnificent CME Erupts on the Sun - August 31

Sun Right Ascension

Posted by AT
Wikipedia defines Right ascension (RA) as the angular distance of a particular point measured eastward along the celestial equator from the Sun at the March equinox to the (hour circle of the) point in question above the earth.  When paired with declination, these astronomical coordinates specify the location of a…
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Proportion Test – Example

Posted by AT
In the previous post, we explained how to calculate P-value and thus perform hypothesis testing for categorical data. In this post we will give an example. A study was performed to see if there is a difference between males and females who use cannabis regularly. The sample size was 134…
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Proportion Test

Posted by AT
The parameter of interest when we deal with categorical data is the sample proportion. An example of a sample proportion could be the proportion of people that are use cannabis. Imagine that we want to compare the proportion of males that are cannabis users to the proportion of females that…
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Null Hypothesis

Posted by AT
Null hypothesis is effectively stating the default situation. It is as you said there is nothing going on. When some one puts forward a claim the null hypothesis is that this claim is not true and needs to be proven. When we are testing between a new claim and the…
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person holding blue holy book

Hilal

Posted by AT
Download our android app! Moslems Must Observe the apparent movement of the sun across the sky in order to performs prayers. There is no consensus on the times of the prayers among different Moslem factions and developing an algorithm was affected by this fact. For example, Sun depression angle considered…
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person wearing beige sweater holding map inside vehicle

Directions On Map

Posted by AT
The direction between any two places on Earth can be calculated using the spherical trigonometry. We can use the following equation to do that Direction Angle =tan-1 (sin(longitude2 - longitude1)/cos(latitude1)*tan(latitude2)-sin(latitude1)*cos(longitude2-longitude1)) In spherical trigonometry values of latitude and longitude represent angles as in the following diagram: Example One famous example is…
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