![]() Three science instruments allow for accurate determination of stellar positions and velocities as well as the spectral properties. Gaia revolves about its axis slowly in about six hours and is composed of two optical space telescopes. The data helps unveil the origin and future evolution of the Solar System and the Milky Way and helps understand stellar and planetary-system evolution and our place in the cosmos. Gaia data allows, for example, for the derivation of asteroid and exoplanet orbits and physical properties. Finnish researchers were strongly involved in the release. On Monday, June 13, ESA released Gaia data in Data Release 3 (DR3). Gaia was launched in December 2013 and has collected science data from July 2014. More importantly, the model also comprises the Yarkovsky effect on Apophis as an acceleration along the transverse direction of motion, \(\rangle\), the difference is 0.The Gaia space mission of the European Space Agency ESA is constructing an ultraprecise three-dimensional map of our Milky Way galaxy, observing almost two billion stars or roughly one percent of all the stars in our galaxy. The choice of 16 asteroids is to have a fair comparison with other models 6, 13, 17, though not all these models use the most massive asteroids. We have implemented a planetary model to compute high-precision ephemeris of the major Solar System objects 16, which includes the Sun, all planets, Pluto, the Moon, and 343 main-belt asteroids, and is consistent with JPL’s DE430 model 17 see Supplementary Note 1 for details and Supplementary Figure 1 for some comparisons.įor the treatment of the NEA, we consider Apophis as a mass-less test-particle subject to the Newtonian gravitational attraction from the Sun, the eight planets, the Moon, Pluto and the 16 most massive main-belt asteroids (see Supplementary Table 1), including post-Newtonian corrections (except for the asteroids) and Earth’s J 2 zonal harmonic see Supplementary Note 2. This imposes having a realistic model for the Solar System dynamics and for the asteroid. Very precise ephemerides are required to compute possible hazardous events of NEAs. While the underlying ephemeris and NEA models differ, the agreement of the values is a reproducible validation for the calculations, which is particularly important and desirable specially for potentially hazardous objects. The value we obtain is essentially the same as the current one reported by the Jet Propulsion Laboratory (JPL) 1 with minor differences in the uncertainties, and is also consistent with preliminary estimates which use high-quality optical observations 15. The results use an independent implementation for the planetary ephemeris and for the orbital dynamics of Apophis, as well as a different numerical integration technique. Our results provide definite predictions for the close approach in 2029 of Apophis, as well as in 20. Here we report independent results for a non-zero value of the unknown transverse Yarkovsky acceleration of Apophis, as determined from optical and radar astrometry data that include 2021 observations. Several attempts to obtain this acceleration for Apophis have reported marginal detections, essentially indistinguishable from a pure gravitational model 7, 12, 13, 14. ![]() The leading source of orbital uncertainty for Apophis is the Yarkovsky effect 2, 5, 6, 7, a dissipating non-gravitational interaction which induces a semi-major axis acceleration due to re-emission of the incident solar radiation 8, 9, 10, 11. ![]() Computing the orbital dynamics of a NEA is a difficult problem, especially for assessing possible hazardous events where high precision is crucial: the NEA orbit is sensitive to several interactions, including post-Newtonian gravitational corrections, tidal effects and non-gravitational forces 3, 4. Apophis (99942), a Near Earth Asteroid (NEA) discovered in 2004, will have a close approach to the Earth on April 13, 2029, with a proximity close to 1/10 of the Earth-Moon distance 1, 2. ![]()
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