instance_of pioneer venus multiprobe
Aeronautics ( from the ancient Greek words  " r ", which means " air ", and  " nautik " which means " ___MASK70___ ", i . e . " ___MASK70___ into the air ") is the ___MASK6___ or ___MASK47___ involved with the study , ___MASK22___ , and manufacturing of air flight capable machines , and the techniques of operating aircraft and rockets within the atmosphere . The British Royal Aeronautical ___MASK19___ identifies the aspects of " aeronautical Art , Science and Engineering " and " the profession of Aeronautics ( which expression includes Astronautics )." A ___MASK21___ is an astronomical body orbiting a ___MASK83___ or stellar remnant that The term " ___MASK21___ " is ancient , with ties to ___MASK63___ , astrology , science , mythology , and religion . Several planets in the Solar System can be seen with the naked eye . These were regarded by many early cultures as divine , or as emissaries of deities . As scientific knowledge advanced , human perception of the planets changed , incorporating a number of disparate objects . In 2006 , the International Astronomical Union ( IAU ) officially adopted a resolution defining planets within the Solar System . This definition is controversial because it excludes many objects of planetary mass based on where or what they orbit . Although eight of the planetary bodies discovered before 1950 remain " planets " under the modern definition , some celestial bodies , such as Ceres , Pallas , Juno and Vesta ( each an object in the solar asteroid ___MASK39___ ), and Pluto ( the first trans - Neptunian object discovered ), that were once considered planets by the scientific community , are no longer viewed as such . A ___MASK67___ or moon is , in the most common usage , an astronomical body that orbits a planet or ___MASK84___ ( or sometimes another Small Solar ___MASK32___ Body ). The apparent ___MASK30___ of a celestial object is a number that is a measure of its brightness as seen by an observer on Earth . The brighter an object appears , the lower its ___MASK30___ value ( i . e . inverse ___MASK51___ ). The Sun , at apparent ___MASK30___ of  27 , is the brightest object in the sky . It is adjusted to the value it would have in the absence of the atmosphere . Furthermore , the ___MASK30___ scale is logarithmic ; a difference of one in ___MASK30___ corresponds to a change in brightness by a factor of , or about 2 . 512 . Venus is the second ___MASK21___ from the Sun , orbiting it every 224 . 7 Earth days . It has the longest rotation ___MASK82___ ( 243 days ) of any ___MASK21___ in the Solar ___MASK32___ and rotates in the opposite ___MASK90___ to most other planets . It has no natural satellite . It is named after the Roman goddess of love and beauty . It is the second - brightest natural object in the night sky after the Moon , reaching an apparent magnitude of  4 . 6 , bright enough to cast shadows . Because Venus orbits within Earth ' s orbit it is an inferior ___MASK21___ and never appears to venture far from the Sun ; its maximum angular distance from the Sun ( elongation ) is 47 . 8 °. The Moon is an astronomical body that orbits ___MASK21___ Earth , being Earth ' s only permanent ___MASK67___ . It is the fifth - largest ___MASK67___ in the Solar ___MASK32___ , and the largest among planetary satellites relative to the size of the ___MASK21___ that it orbits ( its primary ). Following Jupiter ' s satellite Io , the Moon is second - densest satellite among those whose densities are known . On ___MASK4___ 11 , 1958 , Pioneer ___MASK37___ became the first spacecraft launched by NASA , the newly formed space agency of the United States . The flight was the second and most successful of the three Thor - Able space probes . Pioneer 11 ( also known as Pioneer G ) is a robotic ___MASK57___ launched by NASA on April 6 , 1973 to study the asteroid belt , the environment around Jupiter and Saturn , solar wind , cosmic rays , and eventually the far reaches of the Solar System and heliosphere . It was the first probe to encounter Saturn and the second to fly through the asteroid belt and by Jupiter . Due to power constraints and the vast distance to the probe , last contact with the spacecraft was on September 30 , 1995 . The Pioneer Venus Multiprobe , also known as Pioneer Venus 2 or Pioneer 13 was a ___MASK64___ launched in 1978 to explore Venus as part of NASA ' s Pioneer program . In astronomy , the rotation ___MASK82___ of a celestial object is the ___MASK1___ that it takes to complete one revolution around its axis of rotation relative to the background stars . It differs from the planet ' s solar ___MASK97___ , which includes an extra fractional rotation needed to accommodate the portion of the planet ' s orbital ___MASK82___ during one ___MASK97___ . Aerospace is the ___MASK74___ effort in ___MASK6___ , engineering and business to fly in the atmosphere of Earth ( aeronautics ) and surrounding space ( astronautics ). Aerospace organisations research , ___MASK22___ , manufacture , operate , or maintain aircraft and / or ___MASK64___ . Aerospace activity is very diverse , with a multitude of commercial , industrial and ___MASK79___ applications . Earth , otherwise known as the world , is the third ___MASK21___ from the Sun and the only object in the Universe known to ___MASK16___ life . It is the densest ___MASK21___ in the Solar ___MASK32___ and the largest of the four terrestrial planets . The Solar ___MASK32___ is the gravitationally bound ___MASK32___ comprising the Sun and the objects that orbit it , either directly or indirectly . Of those objects that orbit the Sun directly , the largest ___MASK53___ are the planets , with the remainder being significantly smaller objects , such as dwarf planets and small Solar ___MASK32___ bodies . Of the objects that orbit the Sun indirectly , the moons , two are larger than the smallest planet , Mercury . Pioneer 10 ( originally designated Pioneer F ) is an American ___MASK57___ , launched in 1972 and weighing , that completed the first mission to the planet Jupiter . Thereafter , " Pioneer 10 " became the first spacecraft to achieve escape velocity from the Solar System . This space exploration project was conducted by the NASA Ames Research Center in California , and the ___MASK57___ was manufactured by TRW Inc . The Pioneer program is a ___MASK73___ of United States unmanned ___MASK45___ missions that were designed for planetary ___MASK36___ . There were a number of such missions in the program , but the most notable were Pioneer 10 and Pioneer 11 , which explored the outer planets and left the solar ___MASK32___ . Pioneer 10 and Pioneer 11 carry a golden plaque , depicting a man and a woman and information about the origin and the creators of the probes , should any extraterrestrials find them someday . The Sun is the ___MASK83___ at the center of the Solar ___MASK32___ . It is a nearly perfect sphere of hot plasma , with internal convective ___MASK34___ that generates a magnetic field via a dynamo process .< ref name =" doi10 . 1146 / annurev - astro - 081913 - 040012 "></ ref > It is by far the most important source of energy for life on Earth . Its diameter is about 109 times that of Earth , and its mass is about 330 , 000 times that of Earth , accounting for about 99 . 86 % of the total mass of the Solar ___MASK32___ . About three quarters of the Sun ' s mass consists of hydrogen (~ 73 %); the rest is mostly helium (~ 25 %), with much smaller quantities of heavier elements , including oxygen , carbon , neon , and iron . The National Aeronautics and ___MASK45___ ___MASK55___ ( NASA ) is an independent agency of the ___MASK61___ of the United States ___MASK66___ responsible for the civilian space program as well as aeronautics and aerospace research .