![]() ![]() ![]() This is consistent with the measurement that the Earth is slowing down by about 2.3 milliseconds per century. They have measured that the Moon is moving away from us at a rate of 3.8 centimeters a year. Is this measurable? Yes! The astronauts left mirrors on the Moon for scientists to bounce laser light. Therefore, the angular momentum of the slowing Earth is transferred to the Moon-the Moon moves away from the Earth. However, angular momentum needs to be conserved (think of a spinning skater bringing in her/his arms, she/he spins faster). What does this friction do? It slows down the Earth. Think of the Earth spinning with the Moon raising tides. The Earth rotates in one day and the Moon orbits in 27.3 days. However, over time, there is a bigger effect-tides. Major earthquakes have altered the length of the day by only microseconds. When Earth’s rotation alters, say due to earthquakes, does it impact the Moon’s speed? Images of the Sun taken at the same time (8:30 am) and location over a one year periodĪn analemma, similar to the one in front of the Flandreau Science Center in Tucson, AZĤ. There is an additional factor that complicates this- the tilt of the orbit of the Earth. The maximum difference is about 7.7 seconds, but because it adds up from one day to the next, the noon as determined by the Sun or a sundial will be off by as much as 7.7 minutes. The opposite is true when the Earth is farthest away. Similarly, when the Earth is closest to the Sun, the rotation of the Earth falls behind and it takes a little longer for the Sun to go from noon to noon (the day is slightly longer than 24 hours). Therefore, we see more than half of the Moon (the rotation falls behind when the Moon is closest, but ahead when farthest). Because of its elliptical orbit, it is moving faster when closest and slowest when farthest, but its rotation rate is constant. To further the discussion on a slightly more advanced level- recall the motion of the Moon. On July 4, 2011, when the Earth was farthest from the Sun (aphelion, 152.1 million kilometers) it was traveling at 29.3 km/s. On January 3, 2011, when the Earth was at its closest to the Sun (perihelion, 147.1 million kilometers), it was traveling at 30.3 km/s. The orbital speed of the Earth averages 29.78 km/s (107,200 km/hr), which is fast enough to move its own diameter length (about 12,600 km) in seven minutes (and the distance to the Moon (384,000 km) in four hours- taken, in part from Wikipedia). If you are interested in the issue of space junk and possible solution, later this year we will be publishing an in-depth conversation with Dr Jah as part of our podcast The Big Questions.Yes! Earth orbits the Sun at an average distance of 149.6 million kilometers every 365.2564 days. The study was published in the journal Science. I'm excited to work with others in highlighting the links and interconnectedness amongst all things and that marine debris and space debris are both an anthropogenic detriment that is avoidable," Dr Moriba Jah, associate professor of Aerospace Engineering and Engineering Mechanics at The University of Texas at Austin, added. "Ancient TEK (traditional ecological knowledge) informs us how we must embrace stewardship because our lives depend on it. Overpollution there would be to the detriment of all: Space junk can destroy satellites that we rely on in our daily life from communication to protection. Solutions to the current issues do exist, but they require the political will to hold countries and private enterprises to keep space a safe environment. ![]()
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