Birthday gift from the earth: every year you grow up, you can stay in bed for about 0.0003 seconds
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in fact, there were 25 leap seconds from 1972 to 2015 (see the table below). Since 2000, there have been four “leap seconds”. At 23:59:59 GMT on June 30, 2012, add one second, recorded as 23:59:60, and then 00:00:00 the next day. Compared with Beijing time, that is, at 7:59 on July 1, the special phenomenon of 7:59:60 occurs, and then at 8:00:00. A leap second occurred at 7:59:60 on July 1, 2012 Beijing time. On July 1, 2015, Beijing time, there was another leap second at 7:59:60
03 Irregular change
material or energy exchange outside and inside the earth. For example, the impact of meteorites on the earth sometimes accelerates the earth and sometimes slows the earth. Earthquakes often accelerate the earth’s rotation.
on March 11, 2011, a magnitude 8.9 earthquake occurred in the sea area near Honshu Island, Japan (later revised to magnitude 9.0) , the Japanese earthquake is the fifth largest earthquake since 1900. According to an article on the earthquake, according to NASA According to the calculation of geophysicist Richard gross, this earthquake reduced the earth’s daily rotation speed by 1.6 microseconds. A similar situation also occurred in the Chile earthquake in 2010, when the calculation result was 1.26 microseconds, while the Sumatra earthquake in 2004 increased the rotation speed by 6.8 microseconds.
why does the movement of mantle material affect the earth’s rotation? For a rotating earth, its rotation speed is related to its moment of inertia. In short, moment of inertia is the square of mass multiplied by radius. Crustal movement (including earthquake) It will affect the material distribution inside the earth. Generally speaking, the material tends to move where the potential energy is low. For example, water tends to flow to the lower part. After the mantle material moves to the center of the earth, the moment of inertia of the earth will decrease, which will accelerate the rotation speed of the earth.
generally speaking, the rotation of the earth is extremely slow, which means that it will change in the day and night in the future Long. Unless an asteroid comes to “smoke” Go to the earth, otherwise this slowing trend should not stop. Therefore, Xiaobian has a bold idea. As long as Xiaobian lives long enough, he can have enough time to brush the B station, brush the microblog, brush the drama and drink happy water every day!
original title: why does the earth turn slower and slower