One astronomical unit AU is the average distance from the Earth to the Sun , which is about million kilometers 93 million miles. The astronomical unit is commonly used to measure distances between objects within the Solar System or around other stars. For example, at their closest to the Earth, Mars and Jupiter are 0. Despite its name, a light-year is a unit of distance, not a unit of time.
It is the distance that light travels in a vacuum in one Earth-year , which equals 9. You could measure insects in miles and highway distances in inches, and be technically correct. As we measure larger and larger sizes, different units are applied.
The solar system is extremely large and the mile is just too small of a unit to use for measuring interplanetary distances. Instead scientists devised another unit, called the astronomical unit AU , which is convenient to use for making measurements within our solar system.
One astronomical unit is defined as the average distance from the Earth to the Sun, approximately 93,, miles. Then if we say an object is 35 AU from the Earth we mean it is 35 times as far from the Earth as the Earth is from the Sun or 35 times 93 million miles. In reading astronomy people encounter the unit called a Light Year, which is the distance light travels in one year about 6 trillion miles. The Light Year is about 64, times larger than the Astronomical Unit, too large to be appropriate for an object the size of our solar system.
The Light Year is fine for measuring distances to stars or other galaxies but not for measuring distances within our own solar system. Thus the Light Year is just not a practical unit for our solar system.
Astronomers use another distance unit, the parsec, which represents 3. Our Solar System. Planets and Moons. A light year is the distance light travels in one year, while an AU, otherwise known as an astronomical unit, is the distance between the Sun and the Earth. A light year is approximately 9,,,, km. An AU is ,, km. As you can probably tell, an AU is much shorter than a light year.
What is the difference between an astronomical unit and a light year? Astronomy Introduction to Astronomy Astronomy Basics. Dec 23, Explanation: Light travels , kilometers in vacuum in one second. Related questions Why do astronomers use scientific notation to describe sizes?
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