14 DAY TRIAL // During a meeting of the International Astronomical Union (IAU) held last month, experts in the field decided to attach a clear, constant value to an astronomical unit (AU), a measure of the distance between the Earth and the Sun.
Previously, the length of an AU was determined by a large number of ever-changing factors, such as the length of a day, or orbital inclination. Now, the unit has a clearly set value, which can be used as a basis for measuring distances inside the solar system even more accurately.
According to the IAU decision, an AU is now 149,597,870,700 meters, or about 92.956 million miles.
The vote to redefine this critical astronomical unit of measurement was adopted unanimously. Scientists say that it will be much easier to create tables revealing the exact positions of objects in the sky from now on. These charts are called ephemerides.
AUs are also used to measure the motions of various objects inside the solar system, and a great deal of uncertainty was associated with the previous, changing value. Additionally, engineers, software designers and students will now have an easier time understanding this important unit of measurement.
“The new definition is much simpler than the old one,” explains Technical University of Dresden astronomer Sergei Klioner. The expert is part of a larger group of astronomers that have spent the past few years figuring out how to make and implement the change.
“The broader community of astronomers are able now to better, with less efforts, understand what their colleagues – astronomers who are experts in planetary ephemerides – do and how they produce the high-accuracy theories of motion in the solar system,” he adds, quoted by Space.
By using AU instead of angles, astronomers now have an easier time figuring out distances in the Universe. A couple of centuries ago, scientists had to move to the other side of the planet to conduct the same measurements, and then use complex trigonometry to establish distances.
“Expressing distances in the astronomical unit allowed astronomers to overcome the difficulty of measuring distances in some physical unit,” Paris Observatory astronomer Nicole Capitaine says.
“Such a practice was useful for many years, because astronomers were not able to make distance measurements in the solar system as precisely as they could measure angles,” she adds, in an email for Space.