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Current affairs forms an important component of several competitive exams such as the UPSC Civil Services Examination, SSC CGL, Bank PO & PSU entrance tests, etc. Therefore, understanding terms/concepts/events that are in the news is critical for aspirants. We at PaGaLGuY bring you this series of articles in which we shall explain some of these important concepts/events for you.
In this article we are discussing Our Earth & Moon.
Local Time:
a) As we know Earth takes 24 hours to complete the revolution in 360°, it passes through 15° in one hour and 1° in every 4 minutes.
b) We use G.M.T. as a reference to determine the local timing of any place on the surface of earth.
c) There are total 24 time zones in the whole world. Each time zone is of 15°. Russia is the largest country which extends through 165° of longitude divided in eleven time zones.
d) Indian Standard Time is calculated on the basis of 82.5° E longitude in Mirzapur ,Uttar Pradesh) which is nearly on the corresponding longitude reference line. The IST is 5.30 hours ahead of GMT.
e) Time difference between eastern and western extremes in India is of two hours.
International Date Line:
a) If we travel towards the east direction from Greenwich line until we reach 180°E, we will be 12 hrs ahead of GMT. Similarly if we travel westward to 180°W, we will be 12 hrs behind from GMT.
b) There is a difference of a whole day between two sides of 180° meridian. This meridian is called as an International Date Line. If this line is crossed from Eastern side to the western side, we lose a whole day. Similarly, if we cross this line from western side to the eastern side, we end up in losing a whole day.
c) This line passes through Bering Strait in Pacific Ocean.
Moon :
a) Moon is the only satellite of Earth revolving around her in an elliptical orbit. Moon revolves around the earth as well rotates around the sun.
b) When moon is at apogee, it is farthest from the Earth. When its at perigee, it is closest from the Earth.
c) The sidereal period of moon is the time required by moon with respect to some fixed stars. The sidereal period of moon is 27.3 days if observed from earth.
d) The synodical period of moon is the time required by moon with respect to sun. The synodical period of moon is 29.5 days. It is considered as a Lunar month.
e) The effect of gravity on moon is only 17% to the gravity on surface of Earth.
f) The USA’s NASA Apollo 11 mission in 1969 was the first manned Moon landing.
g) The surface of the Moon features a huge number of impact craters from comets and asteroids that have collided with the surface over time. Because the Moon lacks an atmosphere or weather these craters remain well preserved.
h) A lunar eclipse occurs when the Earth is between the Sun and the Moon.
i) The Earth’s tides are largely caused by the gravitational pull of the Moon.
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