Units of measurement in astronomy | Physical constants
An astronomical constant is any of several physical constants used in astronomy. Formal sets of constants, along with recommended values, have been defined by the International Astronomical Union (IAU) several times: in 1964 and in 1976 (with an update in 1994). In 2009 the IAU adopted a new current set, and recognizing that new observations and techniques continuously provide better values for these constants, they decided to not fix these values, but have the Working Group on Numerical Standards continuously maintain a set of Current Best Estimates. The set of constants is widely reproduced in publications such as the Astronomical Almanac of the United States Naval Observatory and HM Nautical Almanac Office. Besides the IAU list of units and constants, also the International Earth Rotation and Reference Systems Service defines constants relevant to the orientation and rotation of the Earth, in its technical notes. The IAU system of constants defines a system of astronomical units for length, mass and time (in fact, several such systems), and also includes constants such as the speed of light and the constant of gravitation which allow transformations between astronomical units and SI units. Slightly different values for the constants are obtained depending on the frame of reference used. Values quoted in barycentric dynamical time (TDB) or equivalent time scales such as the Teph of the Jet Propulsion Laboratory ephemerides represent the mean values that would be measured by an observer on the Earth's surface (strictly, on the surface of the geoid) over a long period of time. The IAU also recommends values in SI units, which are the values which would be measured (in proper length and proper time) by an observer at the barycentre of the Solar System: these are obtained by the following transformations: (Wikipedia).
Teach Astronomy - Fundamental Constants
http://www.teachastronomy.com/ There are several important fundamental constants of nature in astronomy. The first is the speed of light; 3*109 meters per second, or 300 thousand kilometers per second, or 186 thousand miles per second. A huge number, this reflects the fact that light and
From playlist 01. Fundamentals of Science and Astronomy
Teach Astronomy - Astronomical Units
http://www.teachastronomy.com/ The astronomical unit is defined as the mean distance between the Earth and the Sun. It has to be defined as the mean because the orbit is elliptical by a couple of percent. The astronomical unit is 150 million kilometers or 98 million miles. This sets the
From playlist 11. Interplanetary Bodies
From playlist Courses and Series
Teach Astronomy - Measuring the Hubble Constant
http://www.teachastronomy.com/ The Hubble constant sets the current expansion rate of the universe and gives an indication of its size and age. The best currently measured value of the Hubble constant comes from a heroic project done with the Hubble Space Telescope over a number of years.
From playlist 20. Galaxy Interaction and Motion
Parsecs, astronomical units and light years, distance units explained: fizzics.org
Notes to support this video lesson are here: https://www.fizzics.org/measuring-distance-in-astronomy/ Astronomical units , the parsec and the light year are different units commonly used to measure distances in astronomy. Where they come from and how they relate to our basic units of measu
From playlist Astronomy - physics of measuring distance
http://www.teachastronomy.com/ The vast distances to the nearest stars encourage astronomers to use a new unit of distance. Whereas meters and kilometers work well on the Earth, and the astronomical unit is the appropriate unit for scales within the solar system, the distance scale to the
From playlist 14. Stars
Teach Astronomy - Astronomy Units
http://www.teachastronomy.com/ Astronomers use the metric system, but they also use units that are more appropriate to the huge scales of the universe that are encountered in astronomy. In particular they use three different scales of distance. The astronomical unit, the mean distance be
From playlist 01. Fundamentals of Science and Astronomy
Teach Astronomy - Solar Constant
http://www.teachastronomy.com/ The solar constant is the amount of Sun's radiation that reaches the Earth. Assuming the atmosphere to be perfectly transparent, 1,370 joules reach every square meter of the Earth surface every second. Variations in the solar constant are subtle, only about
From playlist 14. Stars
Astronomy - Ch. 9.1: Earth's Atmosphere (33 of 61) What is the Diurnal Temperature Range?
Visit http://ilectureonline.com for more math and science lectures! In this video I will explain what is the diurnal temperature range. It is the range of the lowest temperature in a 24-hour period to the highest temperature in the same 24 hours. I will also explain why the smaller the ra
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Gravitation: Kepler’s Laws of Planetary Motion, Example Problems
This video goes through six example worked example problems for Kepler's third law of planetary motion. Social Media for Step by Step Science: Teacher Pay Teachers Store: https://tinyurl.com/y6d2cdfj Instagram: https://www.instagram.com/stepbystepscience101/ Website: https://stepbysteps
From playlist Gravitation: Orbital Velocity, Orbital Period, Potential Energy, Kinetic Energy, Mass and Weight
Cosmology, the study of the universe as a whole, has been turned on its head by a stunning discovery that the universe is flying apart in all directions at an ever-increasing rate. Is the universe bursting at the seams? Or is nature somehow fooling us? The astronomers whose data reveale
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Where Did Dark Matter And Dark Energy Come From?
Claim your SPECIAL OFFER for MagellanTV here: https://try.magellantv.com/historyoftheuniverse. Start your free trial TODAY so you can watch Other Earths: The Search For Habitable Planets, and the rest of MagellanTV’s science collection: https://www.magellantv.com/video/other-earths-the-sea
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Scientists May Be One Step Closer to Figuring Out How Fast the Universe is Expanding
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How Big is the Hubble Constant? - Sixty Symbols
Its exact value has been the subject of debate, but the Hubble Constant is an important figure in modern astronomy. Featuring Mike Merrifield from the University of Nottingham. The Hubble constant tells us how quickly the universe is expanding and is usually quoted in really odd units. I
From playlist Mike Merrifield - Sixty Symbols
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Studying Dark Energy: Mysterious Force That Shaped The Universe | Cosmic Vistas | Spark
We can’t see it, but dark energy is thought to be a main force shaping the universe. View the latest work to reveal the mysteries of this phenomenon, including a dark energy camera and telescope that will search for it in the movement of galaxies. - Season Five of Cosmic Vistas journeys in
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From playlist UNC: Astronomy 101 by Skynet University | CosmoLearning.org Astronomy
Teach Astronomy - Hubble Constant
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From playlist 20. Galaxy Interaction and Motion