Original reports, explanations and news from their publishers.
As Dawn approached Ceres in 2015, bright spots stood out inside Occator crater. Close observations transformed them from an optical puzzle into evidence for salty liquid moving through the dwarf planet’s crust.
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NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
Eris was identified in 2005 as a distant world comparable to Pluto. Its discovery forced a practical choice: keep adding planets as similar bodies appeared, or define what separated the major planets from this growing outer population.
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NASA, ESA, and M. Brown (California Institute of Technology)
On 21 January 2017, observers at several European sites watched Haumea pass in front of a star. The main disappearance measured the dwarf planet’s silhouette. Smaller, separate dips in the starlight revealed material orbiting around it.
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NASA, ESA, and D. Ragozzine (Brigham Young University); Image Processing: Gladys Kober (NASA/Catholic University of America)
In April 2015, Hubble recorded a faint point beside the bright dwarf planet Makemake. Announced in 2016 and nicknamed MK 2, the companion offered a way to measure the system’s mass and explain part of its combined thermal emission.
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NASA, ESA, and A. Parker and M. Buie (SwRI)
Long before Dawn orbited Vesta in 2011, laboratories held meteorites suspected to come from it. The spacecraft could test that connection by measuring the asteroid’s minerals, chemical composition and the impact scars capable of launching fragments into space.
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NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
OSIRIS-REx delivered material from Bennu on 24 September 2023. In laboratories, the dark grains revealed a history that photographs could not: water-altered minerals, salts and a varied inventory of carbon chemistry inherited from the asteroid’s parent body.
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NASA/Goddard/University of Arizona
Hayabusa2 returned its Ryugu sample capsule to Earth in December 2020. The grains came from two carefully documented touchdowns, including one near an artificial impact crater. Their minerals and chemistry now connect a small rubble-pile asteroid to a much older, water-altered parent body.
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NASA
Psyche reflects radar strongly and appears to contain substantial metal. That made it a candidate remnant of a planetesimal’s core, exposed after collisions removed outer rock. NASA’s Psyche mission is designed to test that interpretation rather than assume it.
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NASA/JPL
On 13 April 2029, Apophis will pass about 32,000 kilometres above Earth’s surface. It will be a close encounter, but NASA’s refined orbit rules out an Earth impact for at least the next century. The scientific opportunity is to observe how a small asteroid responds to a strong gravitational encounter.
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NASA/JPL-Caltech and NSF/AUI/GBO
DART struck Dimorphos on 26 September 2022. The target was the small moon of Didymos, allowing researchers to measure a deliberate orbital change in a compact binary system that posed no impact threat to Earth.
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NASA/JPL
Giotto photographed Halley’s dark nucleus in March 1986, surrounded by escaping material. The comet’s next close passage by the Sun is expected in 2061. Its long absence from bright evening skies follows from the shape of its orbit, rather than a disappearance from the Solar System.
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©ESA · Halley Multicolor Camera Team / Giotto Project · ESA educational/editorial use with attribution; no promotional use.
Rosetta reached comet 67P/Churyumov–Gerasimenko in August 2014 and stayed as it approached the Sun and moved away again. That long encounter let scientists connect a changing surface with the dust and gases escaping from it.
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ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0 · CC BY-SA 3.0 IGO
