Scott Alan Johnston

Jupiter’s largest moon, Ganymede, features a surprisingly strong magnetic field for its size. Tidal effects from Jupiter continually stretch and squeeze the moon, keeping its core warm and driving the magnetic field. But the exact geological processes occurring within the core are not fully understood. Now, a new experimental study has put one of the leading models of core dynamics to the test: the formation of crystalized ‘iron snow’.

Star formation is well understood when it happens in the populous centers of galaxies. From our vantage point on Earth, within the Milky Way, we see it happening all around us. But when newborn stars are birthed in the empty outskirts of galactic space, it requires a new kind of explanation. At the 243rd meeting of the American Astronomical Association yesterday, astronomers announced that they have observed, for the first time, the unique molecular clouds that give rise to star formation near the remote edges of galaxies.

The early universe, according to the Standard Model of Cosmology, ought to be a fairly homogenous place, with little structure or arrangement. In 2021, however, astronomers discovered a large pattern of galaxies forming a giant arc 3.3 billion light years across. Now, a second large-scale pattern has emerged. This time, it’s an enormous circle of … Continue reading "Two Giant Structures Have Been Found Billions of Light-Years Away"

The China National Space Administration (CNSA) has put out a call for international and industry partners to contribute science payloads to its Chang’e-8 lunar lander, set for launch to the Moon in 2028. The mission, which will involve a lander, a rover, and a utility robot, will be China’s first attempt at in-situ resource utilization on the Moon, using lunar regolith to produce brick-like building materials.

April 8’s North American solar eclipse is just around the corner, and it has astronomy fans and weather aficionados alike preparing for an incredible show. But it’s not just fun and games. Eclipses are rare opportunities for scientists to study phenomena that only come around once in a while.

The European Space Agency (ESA)’s next generation heavy lift rocket is just months away from its first flight, and its major components are now being assembled for launch at the Vehicle Assembly Building in Kourou, French Guiana.

For nearly three decades now, it’s been clear that the expansion of the Universe is speeding up. Some unknown quantity, dramatically dubbed ‘dark energy’, is pushing the Universe apart. But the rate at which the Universe’s expansion is increasing – called the Hubble Constant – hasn’t yet been nailed down to a single number.

Catching a supernova in action is tricky business. There is no way to predict them, and they don’t occur very often. Within the Milky Way they only occur about once a century, and the last one was observed in 1604. Of course, supernovae occur in other galaxies too, but you still have to get lucky … Continue reading "Astronomers Catch a Supernova Explode Almost in Realtime"

Astronomers are pretty sure they know where the Moon came from. In the early Solar System, a Mars-sized object dubbed Theia smashed into Earth. This cataclysmic collision knocked a huge mass of material into orbit, which coalesced and cooled into the Moon. But establishing exactly when this occurred is a difficult task. At the 55th annual Lunar and Planetary Science Conference (

Cosmic rays are high-energy particles accelerated to extreme velocities approaching the speed of light. It takes an extremely powerful event to send these bits of matter blazing through the Universe. Astronomers theorize that cosmic rays are ejected by supernova explosions that mark the death of supergiant stars. But recent data collected by the Fermi Gamma-ray … Continue reading "The Mystery of Cosmic Rays Deepens"