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Cosmology has undergone significant changes from 2000 to 2025, marked by an increased understanding of dark matter and dark energy's dominance in the Universe. Evidence gathered in the late 1990s pointed towards these mysterious components making up the majority of the cosmic energy budget, with normal matter contributing a mere 5%. Subsequent data from projects like the Hubble key project, WMAP, and Planck's Cosmic Microwave Background (CMB) observations, alongside extensive supernova and large-scale structure surveys, appeared to solidify this picture. However, tensions have emerged as these different data sets reveal inconsistencies, hinting at a potential need for a breakthrough in cosmological understanding.
The core issue revolves around the Hubble constant, a measure of the Universe's expansion rate. Measurements derived from supernova data, CMB observations, and large-scale structure surveys are not mutually compatible, leading to a significant debate within the scientific community. While some propose a crisis in cosmology, questioning the foundations of the Big Bang and the ΛCDM model, others argue that the situation is less dire. Alterations or modifications to the current cosmological model might be necessary to reconcile the discrepancies and restore order. The DESI survey, designed to measure the evolution of large-scale structure, is crucial in understanding how dark energy affects this evolution. Furthermore, recent research indicates that dark energy may not be constant, challenging our established cosmological history. Astronomers are also finding the sky brighter than previously thought, necessitating a reanalysis of existing data. Studies involving Type Ia supernovae at high redshifts, as highlighted by the Union2 compilation of 557 supernovae, provide crucial data for refining the understanding of dark energy's equation-of-state parameter. These observations, made possible by telescopes such as the Hubble Space Telescope, Gemini, and the Very Large Telescope, are instrumental in probing the expansion history of the Universe and revealing potential variations in dark energy's behavior over cosmic time.
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The Bullseye galaxy, also known as LEDA 1313424, has been revealed as a unique ring galaxy with an unprecedented nine concentric rings. This makes it significantly different from other ring galaxies, as prior to the 2025 discovery of the Bullseye galaxy, no other galaxy had been found with more than three concentric rings. This rare class of galaxies, representing only 1 in 10,000 galaxies, typically forms after a galactic collision which appears as a central galaxy surrounded by a well-defined ring of stars.
The Bullseye galaxy is a spiral galaxy that is in the process of transforming into a ring galaxy. This is because a galactic collision occurred around 50 million years ago. High-resolution imagery from NASA’s Hubble Space Telescope confirmed eight rings, and data from the W. M. Keck Observatory in Hawaii confirmed a ninth ring. Hubble and Keck also pinpointed the cause: a blue dwarf galaxy that sits to the immediate center-left of the main galaxy.
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Astronomers are tracking asteroid 2024 YR4, a space rock with the potential to impact Earth. Recent data shows the probability of a collision in 2032 has been increasing. Initially, the chance of impact was estimated at 1.2%, but has since risen to 3.1%. While this may sound alarming, experts say it's a normal part of refining the asteroid's trajectory.
This asteroid has the potential to wipe out a major city. Scientists use the Torino Scale to rate the potential hazards of near-Earth objects. Currently, asteroid 2024 YR4 has a rating of 3, indicating that it is worthy of attention from astronomers. This ranking reflects the probability that the asteroid is capable of localized destruction. As scientists continue to observe the asteroid, gathering more data on its orbit, the probability of impact is expected to either increase further or drop to zero. Once a definitive miss is confirmed, the asteroid's ranking on the Torino Scale will likely be reassigned to Level 0, indicating no threat.
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