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Astronomers have assembled the largest-ever compilation of high-precision galaxy distances, called Cosmicflows-4. Galaxies, such as the Milky Way, are the building blocks of the universe, each comprised of up to several hundred billion stars. Galaxies beyond our immediate neighborhood are rushing away, faster if they are more distant, which is a consequence of the expansion of the universe that began at the moment of the Big Bang. Measurements of the distances of galaxies, coupled with information about their velocities away from us, determine the scale of the universe and the time that has elapsed since its birth.

“Since galaxies were identified as separate from the Milky Way a hundred years ago, astronomers have been trying to measure their distances,” said Brent Tully, astronomer at the University of Hawaii at Manoa. “Now by combining our more accurate and abundant tools, we are able to measure distances of galaxies, and the related expansion rate of the universe and the time since the universe was born with a precision of a few per cent.”

From the newly published measurements, the researchers derived the expansion rate of the universe, called the Hubble Constant, or H0. The team’s study gives a value of H0=75 kilometers per second per megaparsec or Mpc (1 megaparsec = 3.26 million light years), with very small statistical uncertainty of about 1.5 percent.

There are a number of ways to measure galaxy distances. Generally, individual researchers focus on an individual method. The Cosmicflows program spearheaded by Tully and Kourkchiincludes their own original material from two methods, and additionally incorporates information from many previous studies. Because Cosmicflows-4 includes distances derived from a variety of independent, distinct distance estimators, intercomparisons should mitigate against a large systematic error.

Astronomers have assembled a framework that shows the universe’s age to be a little more than 13 billion years old, however, a dilemma of great significance has arisen in the details.

Physics of the evolution of the universe based on the standard model of cosmology predicts H0=67.5 km/s/Mpc, with an uncertainty of 1 km/s/Mpc. The difference between the measured and predicted values for the Hubble Constant is 7.5 km/s/Mpc – much more than can be expected given the statistical uncertainties. Either there is a fundamental problem with our understanding of the physics of the cosmos, or there is a hidden systematic error in the measurements of galaxy distances.

Cosmicflows-4 is also being used to study how galaxies move individually, in addition to flowing with the overall expansion of the universe. Deviations from this smooth expansion arise due to the gravitational influences of clumps of matter, on scales ranging from our Earth and Sun up to congregations of galaxies on scales of a half billion light years. The mysterious dark matter is the dominant component on larger scales. With knowledge of the motions of galaxies in response to the mass around them, we can recreate the orbits that galaxies have followed since they were formed, giving us a better understanding of how the universe’s vast, dark-matter-dominated structures have formed over the eons of time.


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Voyager 2’s Flyby Sheds Light on Uranus’s Magnetic Mystery

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Voyager 2's Flyby Sheds Light on Uranus's Magnetic Mystery

A recent analysis of 38-year-old data from NASA’s Voyager 2 spacecraft has provided fresh insights into the unique magnetosphere of Uranus, according to a study published on November 11 in Nature Astronomy. During Voyager 2’s 1986 flyby, Uranus’ magnetosphere was found to be unexpectedly distorted by a blast of solar wind. The findings suggest that the planet’s magnetic field behaves unlike any other in the solar system.

Findings Highlight Unusual Magnetic Structures

Jamie Jasinski, a planetary scientist at NASA’s Jet Propulsion Laboratory and California Institute of Technology, and lead author of the study, noted that Voyager 2’s timing happened to coincide with an intense solar wind event, a rare occurrence near Uranus. This compression of Uranus’s magnetosphere, seen only around 4% of the time, is thought to be responsible for the unique measurements Voyager captured. Had the spacecraft arrived even a week earlier, Jasinski observed, these conditions would likely have been different, possibly leading to alternative conclusions about Uranus’s magnetic characteristics.

Unlike Earth, Uranus exhibits a complex “open-closed” magnetic process, influenced by its extreme axial tilt. This tilt subjects Uranus to highly variable solar wind effects, resulting in a magnetosphere that opens and closes cyclically.

Implications for Future Uranus Exploration

The study’s conclusions go beyond Uranus itself, offering insights into the magnetic behaviours of its outermost moons, including Titania and Oberon. These moons, it turns out, lie within Uranus’s magnetosphere rather than outside it, making them candidates for investigations into subsurface oceans through magnetic field detection. As Jasinski highlighted, these conditions would simplify detecting any magnetic signatures that suggest liquid beneath the moons’ icy surfaces.

While Voyager 2 remains the only mission to visit Uranus, the study’s findings underscore a growing interest in exploring the ice giant in greater detail.

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Tajikistan rock shelter reveals ancient human migration routes

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Tajikistan rock shelter reveals ancient human migration routes

Archaeologists have uncovered a rock shelter in Tajikistan’s Zeravshan Valley that was occupied by multiple human species, including Neanderthals, Denisovans, and Homo sapiens, for over 130,000 years. Discovered along the Zeravshan River in the Inner Asian Mountain Corridor (IAMC), this site, known as Soii Havzak, provides new insight into the migration patterns of ancient humans. Researchers believe the IAMC may have facilitated interactions between these groups, offering clues about how they lived and possibly coexisted in Central Asia.

Discovery Along the Zeravshan River

A team led by Dr Yossi Zaidner, senior lecturer at the Institute of Archaeology at the Hebrew University of Jerusalem, recently excavated the site. Evidence of various human occupations was found, including stone tools and animal bones dating from 150,000 to 20,000 years ago. Zaidner noted that Central Asia’s IAMC could have served as a natural migration route, allowing distinct human populations to cross paths. “This discovery is crucial for understanding ancient human presence in Central Asia and how different human species may have interacted here,” he stated in a press release.

Significance for Human Migration and Interaction

Artifacts from Soii Havzak, including stone blades, rock flakes, crafted flints, and signs of fire use, suggest repeated use of the shelter by different human groups. The find highlights Central Asia’s significance in ancient migration routes, with the Zeravshan River likely serving as a pathway for early humans as they dispersed across continents.

A Pathway for Ancient Civilisations

Beyond its prehistoric importance, the Zeravshan Valley later became a key route on the Silk Road, linking distant civilisations such as China and Rome. Researchers expect further studies at Soii Havzak to shed light on the broader implications of this region in ancient human migration and cross-cultural interactions, aiming to deepen understanding of human history and evolution during the Middle Paleolithic era.

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NASA’s Juno shows Jupiter’s storms and moon Amalthea up close

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NASA’s Juno shows Jupiter’s storms and moon Amalthea up close

NASA’s Juno spacecraft has delivered breathtaking images of Jupiter, highlighting the planet’s swirling, multicoloured storms and unique moons. During Juno’s 66th close flyby on October 23, the spacecraft approached the planet’s polar regions and captured close-up views of its fifth-largest moon, Amalthea. The raw images collected by JunoCam have since been processed by citizen scientists, who enhanced colours and contrasts to reveal Jupiter’s atmospheric details in a new light.

Spectacular Details of Jupiter’s Storms Revealed

Citizen scientist Jackie Branc processed one of Juno’s most striking images, showcasing a region on Jupiter called a Folded Filamentary Region (FFR), located near the planet’s subpolar areas. FFRs are known for their complex cloud patterns, which include white billows and fine, thread-like filaments. This recent image captures Jupiter’s stormy atmosphere with an emphasis on these fine details, giving scientists and the public alike a vivid view of the planet’s dynamic weather systems.

Juno’s data, available to the public online, allows enthusiasts and researchers to adjust image features such as contrast and colour balance. This collaborative effort has enabled a range of perspectives on Jupiter’s atmospheric bands, turbulent clouds, and powerful vortices.

Amalthea: A Close-Up of Jupiter’s Unique Moon

Juno also captured images of Amalthea, a small, potato-shaped moon only 84 kilometres in radius. In images processed by Gerald Eichstädt, the white balance was adjusted to distinguish Amalthea from the blackness of space, presenting the moon in stark relief. This view of Amalthea, with its rugged, irregular shape, adds to our understanding of Jupiter’s complex satellite system.

Launched in 2016, the Juno mission was originally planned to conclude in 2021, but its mission has been extended, with plans to end in September 2025. When its mission concludes, Juno will plunge into Jupiter’s atmosphere, marking the end of its successful exploration journey.

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