Reliable with reference to what ?Al-Layth said:Particularly interested in the orbital velocities of the planets
That is a lot of objects! Assuming you do mean Milky way and not just solar system, there are some maps on the web.Al-Layth said:.... all of the various astronomical objects in the milky way galaxy.
I think OP is asking where the input data for the model comes from. Famously, the first quality database of astronomical position observations was Tycho Brahe's (though, where'd the makers of Stonehenge get theirs?). Is there a gold standard today, that such software packages are based on? And/or, the math isn't super complicated: are the models publicly available, with starting points that are refined over time?Baluncore said:There are software packages that do a good job of predicting the positions of astronomical objects.
https://en.wikipedia.org/wiki/Numerical_model_of_the_Solar_System
https://en.wikipedia.org/wiki/VSOP_model
Velocity isn't a measured input, it's an output. A stable orbit has only one possible velocity for each location on the orbit, which can be calculated, if you want - it isn't needed for an orbit model. Measuring a handful of points enables the shape of the orbit to be traced, and then derived mathematically (eccentricity, inclination).Al-Layth said:I am looking for the most relied upon studies that measured the motions of the sun, earth, jupiter...etc any or all of the various astronomical objects in the milky way galaxy. Particularly interested in the orbital velocities of the planets
Al-Layth said:sun, earth, jupiter..
The solar system and milky way galaxy are to very different orders of scale. The planetary movements around the sun are well known of which Russ gave an example, and there are many more astronomers since. The galaxy is orders of magnitude more complicated given the billions of stars, dust clouds, nebula, the dense core, and objects on the other side of the dense core. Nevertheless, there are plenty of galactic maps of stars and objects, and velocities of those objects based on years of observation.Al-Layth said:all of the various astronomical objects in the milky way galaxy.
https://www.esa.int/Science_Explora...tes_richest_star_map_of_our_Galaxy_and_beyondESA’s Gaia mission has produced the richest star catalogue to date, including high-precision measurements of nearly 1.7 billion stars and revealing previously unseen details of our home Galaxy.
I don't believe that can be right. 1% in velocity is 2% of the mass. That's ten earth mass. More if they are far away.ETERNITY Starship said:We have yet to map all the mass in the solar system ... no mass map = no accurate speed map
The future positions do not need to be predicted from first principles with precision model parameters. A model requires integration steps, that will amplify the errors exponentially and catastrophically.ETERNITY Starship said:Ref orbital velocities of planets in our solar system
The speeds constantly change due to subtle interactions with other planets and other non planetary mass
There are several methods to measure the velocities of astronomical objects in the Milky Way, including Doppler shift measurements, proper motion studies, and radial velocity measurements. Doppler shift involves observing the change in wavelength of light emitted by an object due to its motion relative to the observer. Proper motion studies track the apparent motion of stars across the sky over time. Radial velocity measurements use the Doppler effect to determine the speed at which an object is moving towards or away from us.
The Doppler effect refers to the change in frequency or wavelength of a wave in relation to an observer moving relative to the wave source. In astronomy, it helps measure the velocity of an object by observing the shift in spectral lines of the light it emits. When an object moves towards us, its light is blueshifted (shorter wavelengths), and when it moves away, its light is redshifted (longer wavelengths). By measuring these shifts, astronomers can determine the object's velocity along the line of sight.
The accuracy of velocity measurements can vary depending on the method used and the quality of the observational data. Modern spectroscopic techniques, such as those used in radial velocity measurements, can achieve precisions of a few meters per second for nearby stars. Proper motion measurements, especially those from space telescopes like Gaia, can achieve extremely high accuracy, often within microarcseconds per year. However, factors like interstellar medium interference and instrumental limitations can affect the overall precision.
Measuring the velocities of objects in the Milky Way is crucial for understanding the dynamics and structure of our galaxy. It helps astronomers determine the distribution of mass, including dark matter, and study the formation and evolution of the Milky Way. Velocity measurements also aid in identifying and characterizing different stellar populations, such as those in the galactic halo, disk, and bulge, and in tracing the orbits of stars and other objects, which can reveal past interactions and mergers with other galaxies.
There are several challenges in measuring the velocities of astronomical objects. One major challenge is the vast distances involved, which can make it difficult to obtain precise measurements. Interstellar dust and gas can obscure or distort the light from objects, complicating observations. Additionally, the intrinsic variability of some stars and the presence of binary or multiple star systems can affect velocity measurements. Instrumental limitations and the need for long-term observations to detect proper motion also pose significant challenges.