NASA's Planetary Radar Images Slow-Spinning Asteroid 2008 OS7

This collage represents a selection of planetary radar observations of asteroid 2008 OS7 that were made the day before its close approach with our planet on Feb. 2, 2024. The stadium-size near-Earth object passed at a distance of about 1.8 million miles (2.9 million kilometers, or 7 ½ times the distance between Earth and the Moon). Scientists at NASA's Jet Propulsion Laboratory used the powerful 230-foot (70-meter) Goldstone Solar System Radar antenna at the Deep Space Network's facility near Barstow, California, to capture these images. The observations will help scientists better understand the asteroid's size, rotation, shape, and surface details. Until this close approach, very little was known about 2008 OS7 as it has been too distant for planetary radar to image it. The asteroid was discovered on July 30, 2008, during routine search operations for NEOs by the NASA-funded Catalina Sky Survey, which is headquartered at the University of Arizona in Tucson. Observations revealed that the asteroid is comparatively slow rotating, completing one rotation every 29 ½ hours. The rotational period of 2008 OS7 was determined Petr Pravec, at the Astronomical Institute of the Czech Academy of Sciences in Ondřejov, Czech Republic, who observed the asteroid's light curve – or how the brightness of the object changes over time. As the asteroid spins, variations on its shape can change the brightness of reflected light astronomers can see, and those changes can be recorded to understand the period of the asteroid's rotation. The Goldstone observations confirm the asteroid's uncommonly slow rotation. https://photojournal.jpl.nasa.gov/catalog/PIA26149