Astronomers have identified a possible new example of one of the universe’s strangest galaxy types: galaxies that appear to contain little or no dark matter. The newly studied pair, FCC 224 and FCC 240, on the outskirts of the Fornax Cluster, share several unusual traits with the only known pair of controversial dark-matter-deficient galaxies. The findings were uploaded to the arXiv preprint server on May 22.

Since NASA’s Artemis II crew members safely splashed down in the Pacific Ocean on April 10 after their record-setting mission around the moon, science teams have been busy collecting more data and combing through observations collected on the test flight. Results from these science investigations will help support safe human exploration of deep space and provide a blueprint for how future missions will conduct science on the lunar surface as NASA builds a moon base and develops an enduring human presence there.

Asteroids and planetesimals regularly bombarded Earth between about 4.6 billion and 3.5 billion years ago, during the Hadean and Archean eons. Because few rocks today are more than 4 billion years old, our understanding of the planet’s environment during that time is limited. However, samples from the moon and its cratered surface hint at the period’s rate of cosmic impacts.