Monday, February 18, 2013

Friday, February 8, 2013

Calculation of time





The International Date Line

The International Date Line (IDL) is an imaginary line of longitude on the Earth’s surface located at about 180 degrees east (or west) of the Greenwich Meridian.
The date line is shown as an uneven black vertical line in the Time Zone Map above and marks the divide where the date changes by one day. It makes some deviations from the 180-degree meridian to avoid dividing countries in two, especially in the Polynesia region.
The time difference between either side of the International Date Line is not always exactly 24 hours because of local time zone variations.


Read the information given in the power point to know more about the time.
http://www.wisc-online.com/objects/ViewObject.aspx?ID=SOC3702


Here is current location time in Maldives.
http://www.timeanddate.com/worldclock/city.html?n=715

Saturday, February 2, 2013

Phases of the moon



Understanding The Moon Phases
Have you ever wondered what causes the moon phases? We all know that its appearance changes over time. But why? The good way to understand the phases of the moon is to examine an earth-moon-sun diagram:








Moon Phases Simplified

It's probably easiest to understand the moon cycle in this order: new moon and full moon, first quarter and third quarter, and the phases in between.
 new moon occurs when the moon is positioned between the earth and sun. The three objects are in approximate alignment (why "approximate" is explained below). The entire illuminated portion of the moon is on the back side of the moon, the half that we cannot see.

At a full moon, the earth, moon, and sun are in approximate alignment, just as the new moon, but the moon is on the opposite side of the earth, so the entire sunlit part of the moon is facing us. The shadowed portion is entirely hidden from view.

The first quarter and third quarter moons (both often called a "half moon"), happen when the moon is at a 90 degree angle with respect to the earth and sun. So we are seeing exactly half of the moon illuminated and half in shadow.


After the new moon, the sunlit portion is increasing, but less than half, so it is waxing crescent. After the first quarter, the sunlit portion is still increasing, but now it is more than half, so it is waxing gibbous. After the full moon (maximum illumination), the light continually decreases. So the waning gibbous phase occurs next. Following the third quarter is the waning crescent, which wanes until the light is completely gone -- a new moon.

( Ref: http://www.moonconnection.com/moon_phases.phtml)

 
Activity:
1: See this link for a better understanding of the phases of the moon
http://www.science-class.net/PowerPoints/Moon_phases_files/frame.htm 


2: Lunar Cycle: complete the calendar by filling them with the correct moon phases for all days.
http://sciencenetlinks.com/media/filer/2011/10/14/moon_challenge.html  


3: Self check quiz:
http://glencoe.mcgraw-hill.com/sites/0078617006/student_view0/unit7/chapter23/section_2_self-check_quiz-eng_.html 

Eclipses

What is eclipse? and what causes eclipse?

     







Read this  

http://www.publish.csiro.au/multimedia/projects/eclipses/index.htm 

Further reading: http://www.mreclipse.com/Special/SEprimer.html

Once you finished reading do the following activity.

Activity
Quiz 1:
http://www.astronomyquiz.info/lunar-eclipses-quiz.html

Quiz 2:
http://www.astronomyquiz.info/solar-eclipses-quiz.html