For studies of the structure of the Milky Way, our local galaxy, the parsec (pc) is the usual choice. The IAU recognises several other distance units to be used on different scales. The IAU also defines other astronomical units: the astronomical unit of time is 1 day (d) of 86,400 SI seconds (s) (SI is the International System of Units) and the astronomical unit of mass is equal to the mass of the Sun, 1.9891×10 30 kg.īeyond the Solar System the distances in astronomy are so great that using the au becomes too cumbersome. ![]() The unique symbol for the astronomical unit is au. This definition is valid irrespective of the used time scale. According to its definition adopted by the XXVIIIth General Asssembly of the IAU ( IAU 2012 Resolution B2), the astronomical unit is a conventional unit of length equal to 149 597 870 700 m exactly. It is a unit of length approximating the Sun-Earth distance (of about 150 million kilometres) which is of convenient use in astronomy. ![]() One of the most important of these is the astronomical unit. The International Astronomical Union (IAU) is responsible for maintaining and approving a special set of units in astronomy, formally defined in 1976. Scientists may need more exotic units such as measures of current, frequency and other scientific quantities, but the principle is the same, without an agreed scheme of measurement, scientists could not share results and there could be disastrous and costly mistakes. Everyone uses familiar units such as kilograms, kilometres and seconds and they are indispensable in daily life. ![]() The concept of an internationally standardised system of units is one of the most fundamental in experimental science. Measuring the Universe The IAU and astronomical units
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |