Space News & Blog Articles

For generations, scientists have probed the structure and composition of the planet using seismic wave studies. This consists of measuring shock waves caused by Earthquakes as they penetrate and pass through the Earth’s core region. By noting differences in speed (a process known as anisotropy), scientists can determine which regions are denser than others. These studies have led to the predominant geological model that incorporates four distinct layers: a crust and a mantle (composed largely of silicate minerals) and an outer core and inner core composed of nickel-iron.

According to seismologists from The Australian National University (ANU), data obtained in a recent study has shed new light on the deepest parts of Earth’s inner core. In a paper that appeared in Nature Communications, the team reports finding evidence for another distinct layer (a solid metal ball) in the center of Earth’s inner core – an “innermost inner core.” These findings could shed new light on the evolution of our planet and lead to revised geological models of Earth that include five distinct layers instead of the traditional four.

The research was led by Dr. Thanh-Son Pham and Dr. Hrvoje Tkalcic, a postdoctoral fellow and professor with ANU’s Research School of Earth Sciences (RSES), respectively. As they indicate, the team stacked seismic wave data from about 200 earthquakes in the past decade that were magnitude-6 or more. The triggered waveforms were recorded by seismic stations worldwide, which traveled directly through the Earth’s center to the opposite side of the globe (the antipode) before traveling back to the source of the earthquake.

Artist’s impression of Earth’s interior structure. Credit: Argonne National Labs

Anisotropy measurements of Earth’s inner core based on these waves’ travel times revealed previously-unrecorded data about Earth’s interior structure. This included the possible presence of a layered structure in the innermost part of the inner core. “The existence of an internal metallic ball within the inner core, the innermost inner core, was hypothesized about 20 years ago,” said Dr. Pham in an ANU press release. “We now provide another line of evidence to prove the hypothesis.”

The Big Bang may have not been alone. The appearance of all the particles and radiation in the universe may have been joined by another Big Bang that flooded our universe with dark matter particles. And we may be able to detect it.

In the standard cosmological picture the early universe was a very exotic place. Perhaps the most momentous thing to happen in our cosmos was the event of inflation, which at very early times after the Big Bang sent our universe into a period of extremely rapid expansion. When inflation ended, the exotic quantum fields that drove that event decayed, transforming themselves into the flood of particles and radiation that remain today. 

When our universe was less than 20 minutes old, those particles began to assemble themselves into the first protons and neutrons during what we call Big Bang Nucleosynthesis. Big Bang Nucleosynthesis is a pillar of modern cosmology, as the calculations behind it accurately predict the amount of hydrogen and helium in the cosmos.

However, despite the success of our picture of the early universe, we still do not understand dark matter, which is the mysterious and invisible form of matter that takes up the vast majority of mass in the cosmos. The standard assumption in Big Bang models is that whatever process generated particles and radiation also created the dark matter. And after that the dark matter just hung around ignoring everybody else.

But a team of researchers have proposed a new idea. They argue that our inflation and Big Bang Nucleosynthesis eras were not alone. Dark matter may have evolved along a completely separate trajectory. In this scenario when inflation ended it still flooded the universe with particles and radiation. But not dark matter. Instead there was some quantum field remaining that did not decay away. As the universe expanded and cooled, that extra quantum field did eventually transform itself triggering the formation of dark matter.

It’s notoriously difficult to take a picture of a black hole. But when they are surrounded by material we have an opportunity to witness the hole carved out by the event horizon. But what we see in the famous images of black holes isn’t the event horizon itself, but a magnified and enlarged version known as the shadow.

No light can escape the surface of a black hole, a boundary which is known as the event horizon. Because of that simple fact black holes make for frustratingly difficult astronomical targets. They emit no radiation of their own (except for the possibility of the exotic quantum process known as Hawking radiation, but that is far too feeble to be meaningful). Plus, they don’t reflect or refract any surrounding light, so we can only detect them based on their influence on their surroundings.

The most common way to do this is to search for accretion discs, which are rings of material surrounding a black hole consisting of matter flowing into the event horizon. As the matter approaches the black hole, it heats up and glows with intense high energy radiation. We have been able to observe accretion discs around black holes of all sizes, from stellar mass black holes in our galactic neighborhood to the supermassive black holes sitting in the hearts of galaxies.

We’ve also been able to observe the gravitational waves emitted when black holes merge together, and watch as stars orbit around central, unseen centers of gravity.

But starting a few years ago the Event Horizon Telescope has been able to provide a new view of black holes by directly imaging the material in the environment of two supermassive black holes, one in the Virgo galaxy and one in our own. The images show a ghostly glow surrounding a void of complete nothingness.

On March 1, 2023, NASA’s Juno spacecraft flew by Jupiter’s moon Io, coming within 51,500 km (32,030 miles) of the innermost and third-largest of the four Galilean moons. The stunning new images provide the best and closest view of the most volcanic moon in our Solar System since the New Horizons mission flew past Io and the Jupiter system in 2006 on its way to Pluto.

Cleary, Io still looks like a pizza. The mottled and colorful surface comes from the volcanic activity, with hundreds of vents and calderas on the surface that create a variety of features. Volcanic plumes and lava flows across the surface show up in all sorts of colors, from red and yellow to orange and black. Some of the lava “rivers” stretch for hundreds of kilometers.

In its extended mission, Juno has now orbited Jupiter 49 times, and is on course to study several of Jupiter’s moons. This latest flyby of Io was the third of nine flybys of the volcanic moon over the next year, with the first coming in December of 2022. An upcoming flyby next year on February 3, 2024 will come as close as 1,500 km (930 miles) from Io.

Jason Perry, an Io observation expert who has worked with the Cassini, Galileo and HiRISE imaging teams said on Twitter that his first looks at these images show some subtle changes from the New Horizons images.

“Surface changes are pretty subtle but there are at least two,” Perry wrote. “The first is a small flow from the eastern end of East Girru. This is a [volcanic] hotspot first seen by New Horizons in the middle of a mini outburst. Still active according to Juno JIRAM.”

Evolution is a problem-solver, and one of the problems it solved in many different ways is locomotion. Birds fly. Fish swim. Animals walk.

But earthworms found another way to move around the niche they occupy. Can we copy them to explore other worlds?

Earthworms are adapted to moving through the soil, and their segmented bodies allow them to do it. An earthworm has between 100 and 150 segments, and they also have two types of muscles that allow them to move: circular and longitudinal. The muscles and segments allow them to move via crawling. Tiny bristle-like appendages called setae help the earthworms move by preventing them from slipping backward.

Earthworms use the flexibility of their bodies to move using peristalsis. Peristalsis is wave-like motions that move up and down the earthworm’s body segment by segment. It’s similar to how we swallow food: when we swallow, it sends a muscle wave travelling down our esophagus that pushes the food into our stomach.

This close-up video shows an earthworm moving.

Less than a year and a half into its primary mission, the James Webb Space Telescope (JWST) has already revolutionized astronomy as we know it. Using its advanced optics, infrared imaging, and spectrometers, the JWST has provided us with the most detailed and breathtaking images of the cosmos to date. But in the coming years, this telescope and its peers will be joined by another next-generation instrument: the Nancy Grace Roman Space Telescope (RST). Appropriately named after “the Mother of Hubble,” Roman will pick up where Hubble left off by peering back to the beginning of time.

Like Hubble, the RST will have a 2.4-meter (7.9 ft) primary mirror and advanced instruments to capture images in different wavelengths. However, the RST will also have a gigantic 300-megapixel camera – the Wide Field Instrument (WFI) – that will enable a field of view two-hundred times greater than Hubble’s. In a recent study, an international team of NASA-led researchers described a simulation they created that previewed what the RST could see. The resulting data set will enable new experiments and opportunities for the RST once it takes to space in 2027.

The team included researchers from the Astrophysics Science Division at NASA’s Goddard Space Flight Center, the Flatiron Institute’s Center for Computational Astrophysics, the National Astronomical Observatory of Japan (NAOJ), the South African Astronomical Observatory (SAAO), the Space Telescope Science Institute (STScI), the European Southern Observatory (ESO), the Mitchell Institute for Fundamental Physics and Astronomy, the Ecole Polytechnique Fédeérale de Lausanne (EPFL), and multiple universities.

Side view of the simulated Universe, each dot represents a galaxy whose size and brightness corresponding to its mass. Credits: NASA/GSFC/A. Yung

The simulation was based on a well-tested theory of galaxy formation that incorporates the most widely accepted cosmological model – the Lambda Cold Dark Matter (LCDM) model. This allowed the team to simulate five light cones measuring two-square-degree in diameter (about ten times the apparent size of a full Moon) that contained over 5 million galaxies each. These galaxies were distributed across the redshift spectrum (z=1-10), corresponding to distances of 1 million and over 13 billion light-years.