Even with this distance the gravitational pull of the sun is more than the pull of earth. One may think that the moon revolves around the earth because the distance of the moon from the earth is very less than the distance from the sun. Which is lower than the escape velocity needed for the moon to go out of earth’s gravitational pull.īecause of this the moon revolves around earth not sun. Keeping in mind that the revolutionary speed of the moon is $1.02\ kms^$ This is what is known as the escape velocity.ĭetermine a relation for the escape velocity by equating the centripetal force of attraction between the moon and the earth and the gravitational force acting between them and arrive at a numerical value for the escape velocity. However, recall that for the moon to escape the bounds of the earth’s gravitational force and fall under the influence of the Sun’s gravity, it must possess a certain velocity. The earth is moving toward Leo at the dizzying speed of 390 kilometers per second.Hint: We know that the gravitational force of attraction keeps the moon revolving around the earth, and the earth revolving around the Sun. It is more fun, though, to look up into the night sky and find the constellation known as Leo (the Lion). Question: Which of these statements is correct The Sun revolves around Earth and the Earth revolves around the Moon The Sun and Moon revolve around the Earth. We can also specify the direction relative to the CBR. The earth is moving with respect to the CBR at a speed of 390 kilometers per second. Because the CBR permeates all space, we can finally answer the original question fully, using the CBR as the frame of reference.
One of COBE's discoveries was that the earth was moving with respect to this CBR with a well-defined speed and direction. The earth is a little than 4 billion years old based on the decay rate of several radioactive elements. It is the equivalent of the entire universe "glowing with heat." Everyone, pretty much know the earth revolves around the sun and the moon revolves around the earth. This radiation, which remains from the immensely hot and dense primordial fireball that was our early universe, is known as the cosmic microwave background radiation (CBR).
In 1989, the COBE satellite was placed in orbit about the earth (again, the earth is the frame of reference!) to measure the long-diluted radiation echo of the birth of our universe. And God said, Let there be light, and there was light. And the Spirit of God was hovering over the face of the waters. The earth was without form and void, and darkness was over the face of the deep. In the beginning, God created the heavens and the earth. The question arises: Is there some universal frame of reference relative to which we can define the motions of all things? The answer may have been provided by the Cosmic Background Explorer (COBE) satellite. Genesis 1:1-31 ESV / 23 helpful votesNot Helpful. Our motion about our sun was described relative to our sun, while the motion of our local group of galaxies was described as toward the Great Attractor. This Great Attractor, having a mass 100 quadrillion times greater than our sun and span of 500 million light-years, is made of both the visible matter that we can see along with the so-called dark matter that we cannot see.Įach of the motions described above were given relative to some structure. The galaxies in our neighborhood are also rushing at a speed of nearly 1,000 kilometers per second towards a structure called the Great Attractor, a region of space roughly 150 million light-years (one light year is about six trillion miles) away from us. As we consider increasingly large size scales, the speeds involved become absolutely huge! In addition, our solar system-Earth and all-whirls around the center of our galaxy at some 220 kilometers per second, or 490,000 miles per hour. It covers this route at a speed of nearly 30 kilometers per second, or 67,000 miles per hour. Thus, the surface of the earth at the equator moves at a speed of 460 meters per second-or roughly 1,000 miles per hour.Īs schoolchildren, we learn that the earth is moving about our sun in a very nearly circular orbit. The earth rotates once every 23 hours, 56 minutes and 4.09053 seconds, called the sidereal period, and its circumference is roughly 40,075 kilometers. Questions about how fast the earth-or anything, for that matter-is moving are incomplete unless they also ask, "Compared to what?" Without a frame of reference, questions about motion cannot be completely answered.Ĭonsider the movement of the earth's surface with respect to the planet's center.
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