wonderful universe
Asteroids
The IAU ’ s definiton of asteroid is : “ Asteroids , or minor planets , are small and often irregularly shaped celestial bodies . The known majority of them orbit the Sun in the so-called main asteroid belt , between the orbits of the planets Mars and Jupiter . However , due to gravitational perturbations caused by planets as well as non-gravitational perturbations , a continuous migration brings main-belt asteroids closer to Sun , thus crossing the orbits of Mars , Earth , Venus and Mercury .” ( Reference : https :// www . iau . org / public / themes / neo / nea2 /) A total of 12 spaceships developed by United States , Japan and the European Space Agency already visited asteroids . OSIRIS-REX was the last mission to reach an asteroid .
IMAGES COURTESY OF NASA / Goddard / University of Arizona
Left , this mosaic image of asteroid Bennu is composed of 12 PolyCam images collected on Dec . 2 by the OSIRIS-REx spacecraft from a range of 15 miles ( 24 km ). The image was obtained at a 50 ° phase angle between the spacecraft , asteroid and the Sun , and in it , Bennu spans approximately 1,500 pixels in the camera ’ s field of view .
Above , this view of sample site Osprey on asteroid Bennu is a mosaic of images collected by NASA ’ s OSIRIS-REx spacecraft on May 26 . A total of 347 PolyCam images were stitched together and corrected to produce the mosaic , which shows the site at 0.2 inches ( 5 mm ) per pixel at full size . The spacecraft took these images during an 820-foot ( 250-meter ) reconnaissance pass over the site , which is the closest Osprey has been imaged . The pass was designed to provide high-resolution imagery to identify the best areas within the site to collect a sample .
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