Fifty years ago, scientists discovered that the Earth is occasionally hit by cosmic rays of enormous energies. Since then, they have argued about the source of those ultra-high energy cosmic rays - whether they came from our galaxy or outside the Milky Way.
Charged particles may be small, but they matter to astronauts. NASA's Human Research Program (HRP) is investigating these particles to solve one of its biggest challenges for a human journey to Mars: space radiation and its effects on the human body.
In the faint southern constellation of Antlia the careful observer with binoculars will spot a very red star, which varies slightly in brightness from week to week. This very unusual star is called U Antliae and new observations are revealing a remarkably thin spherical shell around it.
Astronomers focused the Hubble Space Telescope on an exoplanet that had already been seen losing its atmosphere, which forms an enormous cloud of hydrogen, giving the planet the appearance of a giant comet.
In research that may prove useful to future lunar explorers, scientists have created the first quantitative map of water and its chemical building blocks trapped in the uppermost portion of the Moon's soil.