When scientists use light years to describe the distances between objects in space, the actual numerical distances are so vast, they're inconceivable to the human mind. The sun, however, is only 0.00001581 light years from Earth! Why are Light Years Used? Hypothetically, if you were to drive non-stop at 60 miles-per-hour, it would take 177 years to make it to the sun. For example, the sun is over 93,000,000 miles from Earth. If you tried to use them to calculate smaller distances, you'd get very small decimals. With 8,760 hours in a year, a light year is equal to 5.88 trillion miles! Light years are normally only used to calculate huge distances. Since light travels at the speed of 186,282 miles per second, it travels over 670,000,000 miles per hour. It is defined as the distance that light travels in 365.25 days. Then open and close each eye, one at a time, and you’ll notice your finger shifting relative to objects at the back of the room.A light year is a unit designed to measure distances between objects in outer space. Place a finger directly in front of your nose. You can demonstrate the angular shift, or parallax, yourself.

That shift is measured as a tiny angle, and is correlated to the distance from the earth to the star. Nearby stars shift their position relative to those that are much farther away. It is more difficult to understand and is linked to the measurement of angles and geometry. Thus the Light Year is just not a practical unit for our solar system.Īstronomers use another distance unit, the parsec, which represents 3.26 light years or about 20 trillion miles. An object 35 AU from Earth would only be a few thousandths of a Light Year away. The Light Year is fine for measuring distances to stars or other galaxies but not for measuring distances within our own solar system. The Light Year is about 64,500 times larger than the Astronomical Unit, too large to be appropriate for an object the size of our solar system. You might wonder why we don’t use this unit when discussing the solar system. In reading astronomy people encounter the unit called a Light Year, which is the distance light travels in one year (about 6 trillion 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. One astronomical unit is defined as the average distance from the Earth to the Sun, approximately 93,000,000 miles. Instead scientists devised another unit, called the astronomical unit (AU), which is convenient to use for making measurements within our solar system. The solar system is extremely large and the mile is just too small of a unit to use for measuring interplanetary distances. But it’s awfully cumbersome to say that a beetle is 0.000016 miles long or that Memphis is 5 069 000 inches from Jackson.Īs we measure larger and larger sizes, different units are applied. You could measure insects in miles and highway distances in inches, and be technically correct. You would measure the length of a bug in inches, or the distance to Memphis in miles.

Whenever we make a measurement, whether in science or everyday life, we choose a unit appropriate to the scale of the object being measured. In 1875 the 'Treaty of the Meter' was signed by the major countries of the world (including the United States), making the meter the official world standard for length. We have continued to refine and change our units, seeking to use those with more permanence. In 1670 a Frenchman, Gabriel Mouton, proposed standardizing the length to relate to a physical measurement of the Earth. Obviously this varied from person to person and there was little standardization. A cubit was the distance from the elbow to the tip of the index finger the foot was the length of a person’s foot a fathom was the length of a man’s outstretched arms. Long ago the human body was used as a reference. There is always a number and some unit (a group of words). We weigh 150 pounds we buy 20 oz of a liquid it is 150 km to the next town we are going 50 mph and so forth. When we make a measurement, we use a number and a name called the unit of the measurement. Vocatio Center for Life Calling and Career.Office of Student Leadership & Engagement.

23 parsecs toau