Smithsonian Astrophysical Observatory

meteorite: meteoroid that has not be vaporized completely as it passes through the atmosphere and reaches the Earth’s surface. Meteor: luminous phenomenon caused by the interaction between the atmosphere and a meteoroid that it disintegrates completely by friction before reaching the Earth’s surface. meteoroid: particles of small size, which come from space and falls attracted by the strength of the Earth’s gravity. micrometer: instrument for measuring small distances and angles in the field of the eyepiece. MPC: Minor Planet Center, located at the Smithsonian Astrophysical Observatory, Cambridge, Massachusetts, U.S.A., under the auspices of the 20 Commission of the International Astronomical Union. It is an organization nonprofit that survives mainly from subscriptions of the services offered. The MPC is responsible for the efficient collection, computing, checking and dissemination of astrometric observations and orbits of asteroids and comets via circulars of MPC. MPEC: Electronic circulars of MPC.

They are distributed by subscription and via email. node: each of the opposing points that the orbit of a star intersects the ecliptic. That distinguishes the ascending node and the descending, according to which the Astro cut the plane of the ecliptic from North to South or South to North. The line that unites them is called line of nodes. obliquity: angle between the axis of rotation of the planet and the pole of its orbit. perihelic, distance: the point of the orbit of an asteroid that is closest to the Sun.

disturbance: gravitational influences of one astronomical body with another. Polarimetry: observational technique based on an empirical relationship of the variation, with the phase angle, of the polarization of the light of the asteroid. precession: slowly, periodic conical motion of the axial rotation of the axis of a body. Radiometry: measurement technique of diameters, and more recently even forms, based on the reflectivity of the asteroids. Resonance: the natural frequency of vibration of a physical system. Resonance phenomena occur in all systems in motion, in the case of asteroids, Kirkwood gaps. secular resonance: occurs when the period of precession of a node or apse is a rational fraction of a similar period of one major planet. sidereal, period: time that it takes a body to return to the same position among the stars. Spacewtach: telescope on Kitt Peak which is used partly to search for asteroids approaching Earth. TDT oTT: terrestrial dynamic time or terrestrial time, timeline used in orbital calculations, it is determined by atomic clocks, therefore independent of the motion of the Earth. TEA: Ephemeris time, system of time measurement based on the measurement of the time of revolution of the earth around the Sun in a given year. TEA is made equal to your around 1902. Since then, the your is has been corrected and in 1996 the your has a difference of 62 seconds (your + 62 = DTT). TU o UTC: universal time or Coordinated Universal time, is the measure of time used by astronomers. It is based on observation. The difference between UTC and the atomic time requires periodic corrections. trans-Neptunian: family of asteroids that they are located after Neptune and Pluto. The first component of this group was discovered in 1992, currently more than 35 are known. Trojans: the two groups of asteroids located on the points the two groups of asteroids located on the Langranianos points preceding and following Jupiter in its orbit.