A backlit image of the comet 67P/Churyumov-Gerasimenko made on March 27, 2016, by the space probe Rosetta, which was built by the European Space Agency, when Rosetta was 329 kilometers (204 miles) from the comet. 67P is approximately 4.3 kilometers (2.7 miles) across at its widest point. #

This mosaic image of the asteroid Bennu is composed of 12 Polycam images collected on December 2, 2018, by the OSIRIS-REx spacecraft from a range of 24 kilometers (15 miles). Bennu is in near-Earth orbit, and measures about 492 meters (1,614 feet) across. #

A closer image shows a region near Bennu's equator that contains many large boulders clustered loosely together by the asteroid's gravity, taken by the Polycam camera on NASA’s OSIRIS-REx spacecraft on April 4, 2019, from a distance of 4.6 kilometers (2.9 miles). For scale, the triangular boulder on the horizon is 9.2 meters (30 feet) high, which is almost as tall as the tail of a C-130 Hercules aircraft. #

This composite image of the primordial contact binary Kuiper Belt object 2014 MU69 (nicknamed Ultima Thule) was compiled from data obtained by NASA's New Horizons spacecraft as it flew by the object on January 1, 2019. Ultima Thule is approximately 35 kilometers (22 miles) long, and orbits the sun at a distance of about 6.7 billion kilometers (4.2 billion miles). #

In January 2005, NASA's Mars-exploration rover Opportunity discovered a meteorite lying on the surface of Mars, the first meteorite of any type ever identified on another planet. Named Heat Shield Rock, it was identified as an iron-nickel meteorite. #

This image made by the Hubble Space Telescope and made available by NASA on March 28, 2019, shows the asteroid 6478 Gault, which is gradually self-destructing. It is spinning so fast, dusty material ejected from the surface has formed two long, thin, cometlike tails. The longer tail stretches more than 800,000 kilometers (500,000 miles) and is roughly 4,800 kilometers (3,000 miles) wide. The streamers will eventually disperse into space. #

In this image obtained by NASA's Dawn space probe, a peak at the south pole of the asteroid Vesta is seen at the lower right. The grooves in the equatorial region are about six miles (10 kilometers) wide. The image was taken on July 24, 2011, from a distance of about 5,200 kilometers (3,200 miles). Vesta is a massive asteroid, with a diameter of approximately 525 kilometers (326 miles), orbiting the sun in the asteroid belt between Mars and Jupiter. #

The trail of a falling object is seen above a residential-apartment block in the Ural city of Chelyabinsk, Russia, in this still image taken from a video on February 15, 2013. A meteor streaked across the sky, exploding in an airburst, sending shock waves to the ground, shattering windows, and injuring hundreds below. #

A local resident shows a fragment thought to be part of a meteorite collected in a snow-covered field in the Yetkulski region outside the Ural city of Chelyabinsk on February 24, 2013. A meteor that exploded over Russia's Ural Mountains and sent fireballs blazing to Earth set off a rush to find fragments of the space rock, which hunters hoped could fetch thousands of dollars apiece. #

A plume of dust (bottom center) from the comet 67P/Churyumov–Gerasimenko, seen by the OSIRIS wide-angle camera on the European Space Agency’s Rosetta spacecraft on July 3, 2016. The shadow of the plume is cast across the basin in the Imhotep region. This plume was especially useful from a scientific perspective. As well as observing the site of the plume and the plume itself, Rosetta went through the ejected material, allowing instruments to collect valuable in situ measurements. Analysis of these data indicates that some as-yet-undetermined source of subsurface energy helped power the plume. #

The Philae lander of the European Space Agency's Rosetta mission landed safely on the surface of the comet 67P/Churyumov-Gerasimenko, as these first two images from the lander's CIVA camera confirm. One of the lander's three feet can be seen in the foreground. The view is a two-image mosaic taken on November 12, 2014. Rosetta and Philae had been riding through space together for more than 10 years. Philae was the first probe to achieve a soft landing on a comet, and Rosetta was the first to rendezvous with a comet and follow it around the sun. #

The comet Pan-STARRS (left) is seen with a one-day-old crescent moon as both set over the Very Large Array radio-telescope antenna dishes near Magdalena, New Mexico, on March 12, 2013. The comet was discovered in June 2011 by the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) in Hawaii. #

The NASA spacecraft Deep Impact collides with the comet Tempel 1 in this image captured by Deep Impact's flyby spacecraft, released on July 4, 2005. The spacecraft collided with the comet, half the size of Manhattan, creating a brilliant cosmic smashup that capped a risky voyage to uncover the building blocks of life on Earth. #

This view of the nucleus of Halley's Comet was obtained by the Halley Multicolor Camera on board the Giotto spacecraft as it passed within 600 kilometers (373 miles) of the comet's nucleus on March 13, 1986. #

The asteroid 243 Ida (left) and its tiny moon, Dactyl (right), as seen by NASA's Galileo spacecraft, an image that provided the first conclusive evidence that natural satellites of asteroids existed. Ida, the large object, is about 56 kilometers (35 miles) long, and Dactyl is about 1.5 kilometers (one mile) wide. This portrait was taken by Galileo's CCD camera on August 28, 1993, from a range of 10,870 kilometers (6,755 miles). #

This image provided by the Japan Aerospace Exploration Agency shows the shadow (center left) of the Japanese unmanned spacecraft Hayabusa2 over the asteroid Ryugu on September 21, 2018. Hayabusa2 released two small Minerva-II1 rovers on the asteroid in a research effort that may provide clues to the origin of the solar system. #