Speaker 1: Welcome to Bedtime Astronomy. Explore the wonders of the cosmos
Speaker 1: with our soothing Bedtime Astronomy podcast. Each episode offers a
Speaker 1: gentle journey through the stars, planets, and beyond, perfect for
Speaker 1: unwinding after a long day. Let's travel through the mysteries
Speaker 1: of the universe as you drift off into a peaceful
Speaker 1: slumber under the night sky. This week in Astronomy, Martian
Speaker 1: slopes ley cake caused by dust, Moon's uneven interior and
Speaker 1: evolving dark matter. Martian slope streaks likely caused by dust,
Speaker 1: not water. A new study has challenged a long standing
Speaker 1: idea that dark streaks seen on the slopes of Mars
Speaker 1: may be caused by liquid water. For years, planetary scientists
Speaker 1: have been intrigued by these mysterious features, dark fingerlike markings
Speaker 1: that appear to creep down dusty Martian cliffs and crater walls,
Speaker 1: the first captured by NASA's Viking mission in the nineteen
Speaker 1: seventies and more recently observed by the Cassis camera on
Speaker 1: ESA's Exomar's trace gas orbiter, had been interpreted by some
Speaker 1: as signs of water flows, potentially even pointing to environments
Speaker 1: where life could exist today. However, new research from scientists
Speaker 1: at Brown University and the University of Burns suggests a
Speaker 1: different story. Instead of flowing water, the evidence now strongly
Speaker 1: points to dry avalanches of dust triggered by wind or
Speaker 1: impact events. The team, led by Valentine Bickel and A.
Speaker 1: Dumas Valentinas, used a machine learning algorithm to build the
Speaker 1: most comprehensive map yet of these slope streaks, analyzing more
Speaker 1: than eighty six thousand high resolution satellite images and cataloging
Speaker 1: over five hundred thousand individual streaks across the Martian surface.
Speaker 1: By cross referencing this data with environmental factors like temperature,
Speaker 1: wind speeds, humidity, and geoligical activity, they found no patterns
Speaker 1: supporting the presence of liquid or frost related processes. Instead,
Speaker 1: they discovered strong associations between streak formation and dry conditions,
Speaker 1: particularly areas with high wind activity and recent dust deposition.
Speaker 1: Some streaks were found to be more common near recent
Speaker 1: impact craters, where shock waves may loosen surface dust, while
Speaker 1: others appeared in regions prone to dust devils or rock falls.
Speaker 1: The researchers concluded that these features are most likely formed
Speaker 1: when fine layers of dust suddenly slide down steep slopes,
Speaker 1: creating the dark temporary markings seen from orbit. These streaks,
Speaker 1: some of which last for years while others fade more quickly,
Speaker 1: are likely part of ongoing dry geological processes that may
Speaker 1: transport millions of tons of dust every year, possibly playing
Speaker 1: an important role in mars climate system. Importantly, this new
Speaker 1: understanding diminishes the likelihood that theseus the streaks mark currently
Speaker 1: habitable environments, easing concerns about contaminating sensitive sites with Earth
Speaker 1: microbes brought by future missions. This also underscores the usefulness
Speaker 1: of big data and machine learning in planetary science, allowing
Speaker 1: researchers to eliminate some hypotheses without the need for immediate
Speaker 1: on site exploration. Ultimately, while the dream of discovering present
Speaker 1: day Martian water remains compelling, this study significantly shifts the
Speaker 1: focus toward understanding Mars as a planet shaped more by
Speaker 1: wind and dust than by water. Moon's uneven interior explains
Speaker 1: nearside farside differences. The Moon's two faces, The familiar nearside
Speaker 1: that always faces Earth and the more mysterious pharcide, have
Speaker 1: long puzzled scientists with their stark differences in appearance and composition.
Speaker 1: The near side is darker, smoother, and marked by vast
Speaker 1: plains of ancient solidified lava, while the far side is
Speaker 1: more rugged, heavily cratered, and and lacking in those widespread
Speaker 1: volcanic features. For decades, researchers have suspected that these visible
Speaker 1: contrasts might be due to differences deep within the Moon's interior,
Speaker 1: but direct evidence has been elusive. Now, using precise data
Speaker 1: from NASA's Gravity Recovery and Interior Laboratory Mission, or GRAIL,
Speaker 1: which involved two spacecraft named EBB and Flow, scientists have
Speaker 1: made a compelling discovery that may explain the mystery. They
Speaker 1: detected a subtle but significant difference in the way the
Speaker 1: Moon's mantle, the layer beneath the crust, responds to stress
Speaker 1: on each hemisphere. Specifically, they found that the mantle on
Speaker 1: the near side is two to three percent more deformable
Speaker 1: than on the far side, suggesting it is also warmer
Speaker 1: by as much as one hundred and seventy degrees celsius.
Speaker 1: This difference in deformability was derived from careful measurements of
Speaker 1: the Moon's gravitational field as it responds to tidal forces
Speaker 1: from Earth, allowing researchers to peer into the Moon's inner
Speaker 1: structure without needing to physically land on its surface. The team,
Speaker 1: led by Ryan Park developed models of the Moon's interior
Speaker 1: and showed that the observed differences could be explained by
Speaker 1: a thermal imbalance between the two sides. According to their analysis,
Speaker 1: this heat difference could stem from the presence of radioactive
Speaker 1: elements like thorium and titanium concentrated in the nearside mantle.
Speaker 1: These elements generate heat as they decay and may have
Speaker 1: kept the nearside warmer over billions of years. This lingering
Speaker 1: warmth could be a leftover effect from the same internal
Speaker 1: processes that fueled extensive volcanic activity on the near side
Speaker 1: between three and four billion years ago, while the cooler
Speaker 1: farcide remained less geologically active. The findings, published in the
Speaker 1: journal Nature offer strong support for the theory that the
Speaker 1: Moon's asymmetric surface features are the result of uneven heating
Speaker 1: in internal composition, rather than external factors alone. Importantly, the
Speaker 1: method used in this research, measuring subll gravitational shifts from orbit,
Speaker 1: can be applied to study the interiors of other celestial
Speaker 1: bodies as well, including Mars and the moons of the
Speaker 1: outer planets like Enceladus and Ganymede. Since it does not
Speaker 1: require landing a spacecraft, it presents a powerful tool for
Speaker 1: probing the hidden interiors of distant worlds and understanding how
Speaker 1: their internal dynamic shape what we see on the surface.
Speaker 1: Evolving dark matter may help solve the Hubble tension, a
Speaker 1: persistent mystery continues to challenge our understanding of the cosmos,
Speaker 1: lurking right at the center of the standard cosmological model.
Speaker 1: While all current observations confirm the idea that the universe
Speaker 1: is expanding, a puzzling inconsistency has emerged between measurements of
Speaker 1: that expansion in the early Universe compared to more recent
Speaker 1: local measurements. The rate of acceleration derived from the early
Speaker 1: universe appears to be slower than what we see closer
Speaker 1: to the press. This discrepancy, known as the Hubble tension problem,
Speaker 1: remains unresolved despite numerous efforts to explain it. Over the years.
Speaker 1: Scientists have floated a wide variety of ideas to address
Speaker 1: the issue. Some suggest that Einstein's theory of general relativity
Speaker 1: might need revision. Others wonder whether dark matter truly exists
Speaker 1: or whether time itself might not tick at a uniform
Speaker 1: pace throughout the cosmos. There are even speculations that the
Speaker 1: entire universe might be rotating in some subtle way. Now,
Speaker 1: a new idea enters the fray. What if dark matter
Speaker 1: itself changes over time While evolving Dark energy has been
Speaker 1: studied in some detail, the idea that dark matter could
Speaker 1: evolve hasn't attracted much attention. That's largely because current observations
Speaker 1: support the existence of a stable, non interacting form of matter,
Speaker 1: dark matter that influences the cosmos through its gravity but
Speaker 1: does not or absorb light. Though we haven't directly detected
Speaker 1: dark matter particles, the gravitational effects they produce match observations
Speaker 1: of galaxies and large scale cosmic structure quite well. Most
Speaker 1: researchers skeptical of dark matter's role prefer to to scard
Speaker 1: it altogether in favor of alternative explanations like modified gravity,
Speaker 1: rather than trying to tweak its properties. However, the new
Speaker 1: proposal suggests that, instead of being completely stable, a portion
Speaker 1: of dark matter could change over time. The researchers explored
Speaker 1: a model where both dark energy and dark matter might evolve,
Speaker 1: but found that varying dark matter alone offered a much
Speaker 1: better match to the data. Their work is built on
Speaker 1: the idea that what we observe in the universe, how
Speaker 1: it expands and evolves, depends on the balance between energy
Speaker 1: and matter. If dark energy is held constant but dark
Speaker 1: matter is allowed to evolve, the effects can resemble those
Speaker 1: produced by a model within constant dark matter and evolving
Speaker 1: dark energy. They proposed a form of dark matter with
Speaker 1: a changing equation of state, essentially, its behavior in relation
Speaker 1: to pressure and energy density shifts over time. To be
Speaker 1: consistent with observations, this equation of state would need to oscillate.
Speaker 1: While this might sound speculative, it isn't entirely unprecedented. Neutrinos,
Speaker 1: for example, have mass, don't interact strongly with light, and
Speaker 1: are a form of hot dark matter. They also exhibit
Speaker 1: oscillating properties in terms of mass. If cold dark matter
Speaker 1: particles had a similar oscillating behavior, it could account for
Speaker 1: the observational mismatch. The model that best fits the data,
Speaker 1: according to the researchers, is one where about fifteen percent
Speaker 1: of cold dark matter behaves in this oscillatory way, while
Speaker 1: the remaining eighty five percent remains standard and stable. This
Speaker 1: hybrid model would help reconcile the day difference between early
Speaker 1: and late measurements of the universe's expansion rate without undermining
Speaker 1: our current understanding of how dark matter behaves on large scales.
Speaker 1: It's important to recognize that the proposed model is still
Speaker 1: in the realm of theory, a toy model meant to
Speaker 1: explore possibilities rather than provide final answers. The researchers themselves
Speaker 1: acknowledge that their approach is broad and doesn't pinpoint specific
Speaker 1: physical characteristics or particle candidates for this oscillating dark matter.
Speaker 1: Even so, their work opens up new avenues for thinking
Speaker 1: about one of cosmology's biggest challenges. It expands the landscape
Speaker 1: of theoretical models and suggests that the concept of evolving
Speaker 1: dark matter may be more than just a fringe idea.
Speaker 1: In the ongoing effort to solve the Hubble tension. This
Speaker 1: line of inquiry could be one more step toward understanding
Speaker 1: the deeper mechanism shaping our universe. Seemed a