To make it easier for non-astronomers to grasp the distances in the universe, it is better to use a distance unit relevant to their lives
Amir Akzel New York Times
The Moon and Mars as photographed about a month ago when Mars passed by the Moon at the angle of view as seen from the Earth. Distant from the Earth 0.04 jet years and 6.5 jet years, respectively
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When astronomers talk about distances in space they use several units, which confuse the general public and even some scientists. The distance to the sun is defined as an "astronomical unit" - about 144 million kilometers. The distance between Earth and Mars is now less than 56 million kilometers - about 0.4 astronomical units. The average distance to other planets is a few astronomical units (5 to Jupiter, 9 to Saturn, 39 to Pluto).
But when we move to the nearest star, astronomers suddenly change the unit of distance. Distances to stars are measured in light years. A light year is the distance that light travels in a year, about 9.6 trillion kilometers.
Most people do not have an intuitive understanding of the size of a light year. A particle of light travels about 300 kilometers per second; It can orbit the Earth a little more than 7 times in that time period. But when you increase the range to the distance that the light particle travels in a year, you must multiply this distance by 60 (seconds in a minute), and again by 60 (minutes in an hour), and by 24 (hours in a day), and by 365 (days in a year).
The nearest star outside the solar system, Alpha Centauri, is 4.2 light years from Earth, about 40 trillion kilometers. When adding further away, astronomers change their unit of distance again. Now they talk about a farsec (about 3.26 light years) and a megafarsec (about 3.26 million light years). No wonder that very few people have an intuitive understanding of astronomical distances.
I propose a new unit of distance - "jet year". A jet year is exactly what its name implies: the distance a jet plane travels in a year when it flies non-stop. People who have flown in airplanes have a good sense of the distance that I call a "jet year". If it is assumed that a jet plane flies at an average speed of about 960 kilometers per hour, the distance it travels in a year is about 8.4 million kilometers. For example, the distance between Earth and Mars now is about 6.5 jet years.
Aircrew members who have worked for 15-14 years have already traveled the distance from Earth to Mars. An air crew member who worked for 40 years and is about to retire traveled the distance between the earth and the sun - about 17 jet years.
The distance unit jet year can also be used to describe the distances between the Earth and stars outside the solar system. Alpha Centauri is about 4.7 million jet years away. This figure gives us a good sense of the distance to it: if we fly non-stop for almost 5 million years, we will reach the nearest star. Sirius is about 9.5 million jet years away, and the center of the Milky Way galaxy is about 30 billion jet years away.
The neighboring galaxy to our galaxy, the Andromeda Galaxy, is distant from us about 2.5 trillion jet years, 2.2 million light years. The Moon, on the other hand, is two flight weeks away, 0.04 jet years.
Website editor's note: The intention behind the use of astronomical units (within the solar system) and light years in deep space is to reduce the numbers and avoid dealing with billions and trillions and millions of trillions. vice versa.
The use of a persec instead of a light year apparently changes a little more than three times and therefore does not actually move the orders of magnitude, but there you can also use the prefixes mega persec and giga persec, which I have not come across in the context of changing light, and then you can shorten distances at least intuitively in space.
And besides, terms set on the scale of human actions may seem outdated. When a fast and equal space plane is developed, the speed of the jet plane may seem ridiculous and the expression jet year will be equivalent to the expression horse power.
Avi Blizovsky
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