Unraveling the Hubble Constant: A New Era of Cosmic Understanding

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In this episode of SpaceTime, we tackle some of the universe's most pressing mysteries, including new insights into the Hubble constant, the surprising geology of Venus, and the building blocks of stellar formation.
Resolving the Hubble Constant Debate
New data from the James Webb Space Telescope may have finally reconciled the long-standing discrepancy in the measurement of the Hubble constant, the rate at which the universe expands. For years, scientists have grappled with differing values derived from cosmic microwave background radiation and supernova observations. Lead author Wendy Friedman discusses how recent findings suggest that the standard model of cosmology holds up, with the Hubble constant now estimated at 70.4 kilometres per second per megaparsec, aligning more closely with earlier measurements. This breakthrough could reshape our understanding of the universe’s expansion and evolution.
Venus's Thin Crust
New research indicates that Venus's crust is unexpectedly thin, challenging previous assumptions about the planet's geology. A study published in Nature Communications reveals that Venus lacks the tectonic activity seen on Earth, resulting in a crust that is about 40 to 65 kilometres thick. This research proposes a model of crust metamorphism that could explain how volcanic activity persists on Venus, despite the absence of plate tectonics. Upcoming missions, including NASA's Davinci and Veritas, aim to gather more data that could confirm these findings and enhance our understanding of Venus's geological processes.
Building Blocks of Stellar Formation
A recent study highlights that the formation of stars is influenced not only by the amount of gas in a galaxy but also by its distribution. Observations from the WALLABY survey, conducted using the Australian Square Kilometre Array Pathfinder Telescope, reveal that star formation is concentrated in areas with higher gas density. Lead author Seona Lee explains how this research sheds light on the intricate processes that govern star formation, suggesting that gas location is critical for the birth of new stars across various galaxy types.
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✍️ Episode References
Astrophysical Journal
https://iopscience.iop.org/journal/0004-637X
Nature Communications
https://www.nature.com/naturecommunications/
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00:00 This is Space Time Series 28, Episode 66 for broadcast on 2 June 2025
01:00 Resolving the Hubble constant debate
12:15 Venus's surprisingly thin crust
22:30 Building blocks of stellar formation
30:00 Science report: New links between autism and Parkinson's disease