Scott Alan Johnston, Author at Universe Today

April 3, 2024April 3, 2024 by Scott Alan Johnston

What's the Earliest the Moon Could Have Formed?

Artist's impression of the giant impact that shaped the Earth and created the Moon. Credit: NASA/JPL-Caltech.

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 (LPSC 55) last month in The Woodlands, Texas, researchers proposed a new timeline of events that moves the giant impact earlier than previous predictions, at just 50 million years after the formation of the Solar System.

March 29, 2024March 29, 2024 by Scott Alan Johnston

Astronomers Catch a Supernova Explode Almost in Realtime

A composite image taken with the Liverpool Telescope showing the location of SN 2023ixf, a red supergiant supernova (the most blue object in the rectangle) that occurred 22 million light-years from Earth in the Pinwheel Galaxy. Credit: E. Zimmerman et al., Weizmann Institute of Science/Liverpool Telescope.

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.

March 23, 2024March 23, 2024 by Scott Alan Johnston

Red Giants Offer a New Way to Measure Distance in the Universe

The Large Magellanic cloud. Credit: CTIO/NOIRLab/NSF/AURA/SMASH/D. Nidever (Montana State University) Image processing: Travis Rector (University of Alaska Anchorage), Mahdi Zamani & Davide de Martin.

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.

Not for lack of trying.

March 10, 2024March 10, 2024 by Scott Alan Johnston

Ariane 6 is Coming Together

Part of the first Ariane 6 rocket inside the Vehicle Assembly Building, Kourou, French Guiana earlier in 2024. Credit: ESA/CNES/Arianespace/Arianegroup.

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.

February 22, 2024February 22, 2024 by Scott Alan Johnston

If Hycean Worlds Really Exist, What are Their Oceans Like?

Artist's impression of possible hycean world K2-18 b. Credit: NASA, ESA, CSA, Joseph Olmsted (STScI)

Astronomers have been on the hunt for a new kind of exoplanet in recent years – one especially suited for habitability. They’re called hycean worlds, and they’re characterized by vast liquid water oceans and thick hydrogen-rich atmospheres. The name was coined in 2021 by Cambridge astronomer Nikku Madhusudhan, whose team got a close-up look at one possible hycean world, K2-18b, using the James Webb Space Telescope in 2023. In a newly accepted paper this January, Madhusudhan and coauthor Frances Rigby examined what the internal structure of hycean planets might look like, and what that means for the possibility of finding life within.

February 17, 2024February 17, 2024 by Scott Alan Johnston

China's Chang'e-8 Mission Will Try to Make Bricks on the Moon

Artist's impression of Chang'e-8. Credit: CNSA.

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.

January 13, 2024January 13, 2024 by Scott Alan Johnston

Two Giant Structures Have Been Found Billions of Light-Years Away

Artistic impression of the Giant Arc and the Big Ring on the sky. Background image credit: Stellarium.

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 galaxies, nicknamed the Big Ring. Together, the Giant Arc and the Big Ring present a challenge to the Standard Model, and may send cosmologists back to the drawing board.

January 9, 2024January 9, 2024 by Scott Alan Johnston

Young Stars in the Outskirts of Galaxies Finally Have an Explanation

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.

January 3, 2024January 3, 2024 by Scott Alan Johnston

Iron Snow Could Explain the Magnetic Fields at Worlds Like Ganymede

Iron snow in the core of Ganymede. Credits: Image by Ludovic Huguet and map texture from NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

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’.