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Our Cosmic Address: Where is Earth Situated in the Universe?
When measuring distances on Earth, we use inches, feet, yards, meters, miles, kilometers, and so on. However, when we try to describe the placements of planetary or stellar bodies in space relative to Earth, it becomes impractical to use the same units. Instead, when speaking in terms of the cosmos, we use significantly larger units of measurement to quantify vast distances. The smallest of these common units is the Astronomical Unit (AU),which describes the distance between the Earth and the Sun. One AU equates to about 150 million kilometers, 93 million miles, or around 8 light minutes.
For example, it is easier to describe Saturn’s relative distance to us in AU rather than kilometers. On average, Saturn orbits 1,427,000,000 km away from Earth; however, it is more practical to say that Saturn orbits at a mean distance of 9.5 AU.
The second way in which we describe distances within the universe is by the time it takes light to travel to that given distance. The speed of light is a universal constant and the fastest speed at which anything can move — it is a cosmic speed limit. Light travels through a vacuum at exactly 299,792,458 meters (983,571,056 feet) per second, which equates to approximately 186,282 miles per second. It is commonly denoted as c = 3 x 10⁸ m/s in calculations, where ‘c’ represents the speed of…
