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This is Space Time, Series 28, Episode 86, for broadcast on the
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18th of July, 2025. Coming up on Space Time, the youngest
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basaltic lunar meteorite ever found on Earth. Could
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hypothetical objects called dark dwarves be lurking at the center
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of our galaxy, and could they help explain dark matter? And
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astronomers use adaptive optics to get a new view of the
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spectacular Carina Nebula.
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All that and more coming up on Space Time.
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Welcome to Space Time with Stuart Gary.
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Scientists studying a 2.35 billion year old meteorite have
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filled a billion year gap in the Moon's volcanic history. The
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ancient space rock, catalogued as Northwest Africa 16286, was
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purchased from a dealer in Algeria back in February 2023.
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Its providence before that remains uncertain. What is known
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is that the 311-gram specimen has a unique chemical signature.
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The findings of its examination, presented at the Goldschmidt
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Conference in Prague, are offering fresh insights into how
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the Moon's interior evolved, highlighting the long-lived
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nature of its volcanic activity.
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The analysis lends weight to the hypothesis that the Moon
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retained internal heat generating processes which
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powered lunar volcanic activity in several distinct phases. A
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lead isotope analysis dates the rock's formation to around 2.35
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billion years ago, and that's during a period in which few
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lunar samples exist.
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And that also makes this the youngest basaltic lunar
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meteorite ever discovered on Earth. In fact, its rare
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geochemical profile sets it apart from those returned by
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previous Moon missions. With chemical evidence indicating it
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likely formed from a lava flow that solidified after emerging
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from deep within the lunar interior.
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The study's lead author Joshua Snape from the University Of
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Manchester says lunar rocks from sample return missions provide
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fantastic insights, but they're limited to the immediate areas
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surrounding the mission's landing site. By contrast, lunar
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meteorites can potentially be ejected by impact cratering
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occurring anywhere on the Moon's surface.
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As such, there's some serendipity surrounding this
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sample. As it reveals secrets about lunar geology without the
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massive expense of a space mission. The meteorite contains
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relatively large crystals of the mineral olivine. The rock's a
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type of lunar volcanic basalt known as olivine pyrrhic basalt.
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It contains moderate levels of titanium and high levels of
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potassium. In addition to the unusual age of the sample, the
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study also found that the lead isotope composition of this
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rock, that is the geochemical fingerprint retained from when
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the rock first formed, points to it originating from a source in
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the Moon's interior with an unusually high uranium-to-lead
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ratio.
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And these chemical clues may help identify the mechanisms
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that have enabled periods of ongoing internal heat generation
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on the Moon.
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Snape says the age of the sample is especially interesting
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because it fills an almost billion-year gap in science's
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understanding of lunar volcanic history. It's younger than the
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basalts collected by the Apollo, Luna and Chang'E 6 missions, but
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it's older than the much younger rocks brought back by Chang'e 5.
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He says its age and composition showed that volcanic activity
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continued on the Moon throughout this time span. And the analysis
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suggests an ongoing heat generation process within the
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Moon, potentially from radiogenic elements decaying and
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producing heat over long periods. Moon rocks are rare.
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This particular rock provides new constraints about when and
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how volcanic activity occurred on the Moon.
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This meteorite is one of only 31 lunar basalt meteorites
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officially identified on Earth. Its distinct composition with
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melted glassy pockets and veins, suggests that it was likely
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shocked by an asteroid and meteorite impact on the Moon's
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surface before being ejected into space and eventually
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falling to Earth.
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Of course, this shock event also makes it more challenging to
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interpret the date obtained for the rock, but the researchers
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have estimated its age with a margin of plus or minus 80
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million years. This is space-time.
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Still to come, a new study suggests that hypothetical
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objects known as dark dwarves exist at the centre of the
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galaxy and could reveal the true nature of that mysterious
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substance known as dark matter. And astronomers use adaptive
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optics to undertake a new study of the western wall of the
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Korean nebula in unprecedented detail. All that and more still
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to come on Space Time.
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A new study suggests that hypothetical objects which would
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be named dark dwarves could reveal the true nature of that
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mysterious substance known as dark matter. Dark matter is an
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invisible material that makes up around 80% of all the matter in
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the universe. Scientists have no idea what it is, but they know
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it exists because they can see its gravitational influence on
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so-called normal or baryonic matter.
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For example, it prevents galaxies from flying apart as
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they revolve, and it acts as a magnifying lens to amplify light
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coming from more distant objects behind it. But working out a way
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to identify what dark matter is has been problematic. Now, a
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report in the Journal Of Cosmology and Astroparticle
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Physics come up with a hypothetical object which may
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well provide an answer.
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They've named these objects dark dwarves, not because they're
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dark bodies, but because of their special link with dark
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matter. One of the study's authors, Jeremy Saxton from the
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University Of Hawaii, says that among the best-known dark matter
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candidates are what are called weakly interacting massive
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particles, better known as WIMPs.
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These are very massive particles that interact very weakly with
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ordinary matter. They pass through things unnoticed, don't
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emit light, and don't respond to electromagnetic forces. So they
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don't reflect light and therefore remain invisible,
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revealing themselves only through their gravitational
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effects. Now this type of dark matter would be necessary in
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order for Dark Dwarfs to exist.
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The thing is, because dark matter interacts
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gravitationally, it could also be captured by stars, which have
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powerful gravitational fields. And therefore it could
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accumulate inside them. Now, if that happens, dark matter might
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also interact with itself, resulting in annihilation.
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Annihilation would release energy, and that would heat the
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star up.
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Studies like the one Saxton and colleagues are now doing are
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important because they offer concrete tools in order to break
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the deadlock on discovering what dark matter really is.
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So, what are dark dwarves? Well, ordinary stars like our Sun, for
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example, shine because of nuclear fusion processes which
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occur in their cores, generating huge amounts of heat and energy.
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Fusion happens when a star's mass is large enough so that
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gravitational forces compress matter towards the centre of the
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star, and they do that with such intensity they trigger reactions
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between atomic nuclei.
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This is nuclear fusion. And the process releases huge amounts of
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energy, which we see as light. Sexteen says dark dwarves also
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emit light, but not because of nuclear fusion. They don't have
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enough mass to do that. In fact, they're very low-mass objects,
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less than about 8% the mass of the Sun. And that's not
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sufficient to trigger fusion reactions.
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The answer are brown dwarves. They fill a gap between the
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largest planets and the smallest red dwarf stars. And they do
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emit a faint light, energy produced by their relatively
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small gravitational contraction.
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The idea of this new hypothesis is that if brown dwarves are
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located in regions where dark matter is especially abundant,
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such as for example the centre of our galaxy, then they could
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transform into something else, what Sextine describes as a dark
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dwarf.
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Sextine explains that the more dark matter you have around, the
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more you can capture. And the more dark matter ends up inside
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the star, the more energy will be produced through the
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annihilation of dark matter.
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Other candidates propose to explain what dark matter is, are
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hypothetical particles such as axions or sterile neutrinos. But
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all these lack the mass needed to produce the expected effect
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needed for dark dwarves.
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Only massive particles capable of interacting with each other
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and annihilating into visible energy could power a dark dwarf.
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Of course, this entire hypothesis would have little
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value if there wasn't a concrete way to identify a dark dwarf if
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you saw it.
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Saxton and colleagues propose a distinctive marker. He says
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while there'd be several markers available, he believes the
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isotope lithium-7 would be the best because it would have a
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unique effect. See, lithium-7... Burns very easily and is quickly
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consumed in ordinary stars.
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So if you were able to find an object which looked like a dark
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dwarf, you could look for the presence of lithium-7 in its
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spectra, because it wouldn't be there if it was a brown dwarf or
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a similar object. This is space-time.
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Still to come, astronomers use adaptive optics to study the
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spectacular western wall of the Korean nebula in unprecedented
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detail. And later in the science report. A new study is mapping
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killer whale populations in Australian waters for the very
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first time. All that and more still to come on Space Time.
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Astronomers using the International Gemini South
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Observatory have captured the western wall of the spectacular
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Korean nebula in unprecedented detail. The amazing new image
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uses the process of adaptive optics, resulting in a tenfold
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improvement in sharpness in order to reveal a number of
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unusual structures within this amazing nebula.
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For astronomers, looking through the Earth's atmosphere is a lot
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like looking at the sky from the bottom of a swimming pool full
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of water. The atmosphere's density, temperature, inversion
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layers, turbulence and composition all cause photons to
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bounce around. It's what makes stars twinkle in the night sky,
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which is great for romance, but not so good for astronomers.
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Adaptive optics works by using lasers to measure changes in the
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atmosphere directly above the observatory's telescopes. It
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then corrects for these changes using actuators to constantly
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change the shape of the telescope's mirror, effectively
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compensating for the atmosphere.
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With the help of adaptive optics on the 8.1-metre Gemini South
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telescope in Chile, astronomers have been able to state the
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Carina Nebula with new eyes. The brilliant Carina Nebula, located
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in the Southern Hemisphere sky, is some 500 times larger than
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the better-known Orion Nebula, making it an ideal candidate for
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investigating star formation.
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The astronomers' use of adaptive optics allowed them to
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significantly improve upon previous observations of Carina
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's western wall, the nebula's world-defined edge. The thing
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is, Star-forming regions are shrouded in dust and gas. These
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are normally impenetrable to optical telescopes.
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But by looking through the infrared part of the spectrum,
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astronomers can see through this gas and dust. These latest
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observations by Patrick Hartigan from Rice University utilised
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the Gemini South's Adaptive Optics Imager and their Infrared
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Adaptive Optics Camera to peer through the outer layers of dust
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to reveal a huge wall of gas and dust glowing with the intense
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ultraviolet light from nearby massive young stars.
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Astronomers examined this region with the infrared wavelength of
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molecular hydrogen, 2120 nanometers. And molecular
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hydrogen is the best way to trace these structures because
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they'd otherwise be rendered invisible by dust blocking them
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at optical and ultraviolet wavelengths, which is where the
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Hubble Space Telescope operates.
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With a resolution 10 times higher than it would be without
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adaptive optics from the ground, these new images are twice as
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sharp as those from the Hubble Space Telescope at this
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wavelength. And they reveal a wealth of detail never observed
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before. The western wall is a mountainous section of the
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nebula, with a long series of parallel ridges that may be
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being produced by a magnetic field.
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There's a remarkable, almost perfectly smooth wave, and there
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are fragments that appear to be in the process of being sheared
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off the cloud by a strong stellar wind. There's also
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evidence of a jet of material being ejected from a newly
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formed star.
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Hartigan says the data in this new image provides the sharpest
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view to date of how massive young stars affect their
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surroundings and how they influence the star and planetary
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formation process.
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He says it's possible that the Sun and its planetary system
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formed in exactly the same sort of environment. If so, radiation
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and winds from any nearby massive stars would also have
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affected the masses and atmospheres of our solar system
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's outer planets.
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Gemini South is a large telescope. It is eight meters in
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diameter. And it sits atop of a mountain in the Andes in Chile.
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And what this instrument does is it allows you to get very, very
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sharp images of objects because what it does is it actually
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distorts the shape of the mirror. So that compensates for
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any sort of shimmering in the Earth's atmosphere. And the
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other reason for going down there where you have to take the
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images in the Southern Hemisphere is that there are
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some parts of the sky that just are never... Visible from the
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north.
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Well, Karina is a very interesting area of star
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formation because it's probably the nearest star-forming region
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to us that has really, really massive stars. And that's very
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important because what it does, what the massive stars do, is
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they emit a lot of radiation and that can actually affect the
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surrounding cloud out of which other stars are form.
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These images really show clearly for the first time how star
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formation proceeds in regions that have massive stars, and an
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awful lot of stars form in those kind of regions.
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Ultimately, this is the story of creation, because what you're
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doing is you're looking at regions that are actually
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forming new stars and planets. So a couple million years from
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now, there will be new stars and planets there that don't exist
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now.
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And those will go through their lives and will be shining long
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after the Earth and the Sun have disappeared. In the meantime,
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the Sun will have thrown off its outer layers back into the
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interstellar medium, and then those provide new gases for new
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clouds, which then in the future form new stars. So there's this
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really large cycle of stellar life that is occurring.
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And what we're doing here is we're actually seeing into the
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stellar nurseries. In very high detail through the dust, which
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is what the infrared light gives you, and you can really begin to
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see what's happening right at the beginning when stars and
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planets are forming.
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That's Rice University's Professor Patrick Hartigan, and
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this is Space Time.
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And time now to take another brief look at some of the other
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stories making news in science this week with a science report.
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A new study has found significant levels of
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nanoplastics in water samples taken across the Atlantic Ocean.
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Nanoplastics are fragments of plastic less than a thousandth
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of a millimetre in size. A report in the journal Nature
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analysed samples taken from the top 10 metres of Atlantic
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coastal waters at a dozen separate locations.
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The authors found that all these samples contained high
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concentration of nanoplastics. Particles. They say the average
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nanoplastic concentration at a depth of 10 metres was around
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18.1 milligrams per cubic metre of water. Samples taken from the
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sea floor had an average concentration of 5.5 milligrams
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per cubic metre.
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And samples taken from near coastlines in Europe had
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concentrations of around 25 milligrams per cubic metre. The
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authors estimate that nanoplastic pollution in the top
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10 metres of water in the North Atlantic is probably around 27
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million tonnes. And that was previously thought to be the
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amount polluting the Earth's entire ocean system.
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Australians have one of the longest life expectancies on
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Earth, with the average Aussie living for around 83.92 years.
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But there are some steep socio-economic differences. Now,
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a report in the Lancet Medical Journal claims Australia has
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made progress in reducing some of those socio-economic
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equalities in life expectancy, which were widening up until the
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late 2010s.
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However, the findings by the Australian National University
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show that although there was a narrowing of the gap in life
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expectancy across socioeconomic groups from the late 2010s
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onwards, the impact of the COVID-19 pandemic on women
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reversed that positive trend. In fact, overall, the authors found
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that the socioeconomic gap in life expectancy was larger in
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the period 2020-2022 compared to what it was between 2013 and
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2015.
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Well, although they're well documented in the Northern
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Hemisphere and around Antarctica, much less is known
00:17:13
about killer whales in Australian waters. That's a bit
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puzzling because orcas are actually commonly sighted
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year-round in all coastal waters around Australia.
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So now a new study by Flinders University has been mapping
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these tooth cetaceans in local waters in order to model their
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distribution and shed light on the local habitat preferences in
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the process uncovering ecological distinctions between
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different killer whale populations.
00:17:39
The Trump administration has followed through on the
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president's election promise, releasing tens of thousands of
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documents and records related to the assassination of President
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John F. Kennedy.
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And that public disclosure has now forced the CIA, America's
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main spy agency, to admit for the first time that an officer
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specializing in psychological warfare ran an operation that
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came into contact with Lee Harvey Oswald before the Dallas
00:18:03
killing. The importance of this discovery is that the
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confirmation shows the CIA had lied for decades about its role
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both before and after the assassination.
00:18:13
The previously hidden January 17, 1963 document is a CIA memo
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showing that George Gernades, the deputy chief of the CIA's
00:18:21
Miami branch, used the alias Howard Griebler. Until now, the
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agency had denied that Griebler was a cover name used for an
00:18:29
operative working with an anti-Communist group opposed to
00:18:32
Cuban dictator Fidel Castro.
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In fact, for decades, the spy agency falsely claimed that it
00:18:37
had nothing to do with this group, which was instrumental in
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having Oswald's Pro-Castro stances publicised soon after
00:18:43
the shooting. Cheney's oversaw all aspects of political action
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and psychological warfare, including covertly funding and
00:18:51
directing the Anti-Castro activists commonly referred to
00:18:54
as DRE.
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In fact, it was four DRE activists who got into that
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now-famous scuffle with Oswald in New Orleans when he was
00:19:02
passing out Pro-Castro Fair Play for Cuba Committee pamphlets.
00:19:06
Interestingly, the Fair Play For Cuba Committee was yet another
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CIA-inspired operation.
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It was also the DRE who debated Castro on local New Orleans
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television in August 1963, which provided more media attention,
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setting him up and showing him to be a Communist. A year
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earlier, the Pentagon had formulated a plan called
00:19:25
Operation Northwoods. It was designed to stage a false flag
00:19:28
attack on the United States. Blame Cuba for the attack and
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then use that as an excuse to attack the Communist nation.
00:19:35
These new documents still don't shed any fresh light on whether
00:19:39
Oswald acted alone when he used his manly Kakano rifle to shoot
00:19:43
the president from the Texas schoolbook depository on
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November 22, 1963.
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Or if the CIA hired a mafia contract hitman to act as a
00:19:52
second shooter, so as to ensure Kennedy was neutralized to
00:19:56
prevent him from undertaking two of his stated aims. Breaking up
00:19:59
the CIA and limiting American involvement in the Vietnam War.
00:20:03
The thing is, these new documents do confirm that the
00:20:06
CIA knew Oswald before the assassination. Tim Mendham from
00:20:10
Strand Skeptics says the huge document release and the
00:20:13
discoveries being made will keep conspiracy theorists, both those
00:20:17
steeped in reality and the others, going for years.
00:20:20
People are still looking for them and they're still trying to
00:20:21
find the smoking gun, as we talk about.
00:20:24
Yes, so there's still no evidence of a second gunman on
00:20:26
the grassy knoll then? None.
00:20:27
No one's aware of it. There's an article that came out recently
00:20:30
by... Someone named Rebecca Watson, who's a known long-term
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skeptic, looking into a lot of the information there,
00:20:36
especially looking into the film JFK. It came out 20 years ago,
00:20:39
whatever. Looking at the JFK assassination, it had a lot of
00:20:42
conspiracy stuff in it and a lot of false information in it that
00:20:45
was being presented as fact, despite how many years is it
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now?
00:20:49
November 1963, was it?
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That's right, yes. I'm old enough to remember it.
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A friend of mine was actually a student in Dallas at the time.
00:20:56
And she remembers exactly what happened on that day. The
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classes were stopped and they were all told about it and they
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were all very sad and the whole town sort of shut down, the
00:21:04
whole city. And this is a... Even back then, Dallas was a big
00:21:07
city.
00:21:07
The one conspiracy you might get, this is sort of going on a
00:21:11
tangent, if you could get out of the Kennedy assassination was
00:21:13
the rise of British pop popularity in the US because, as
00:21:17
people have said, the Beatles first arrived soon after their
00:21:20
big tour. It was the first time they were in the US performing
00:21:22
Ed Sullivan's show.
00:21:23
It was early 64 and... Their sense of jollity and joy and
00:21:28
excitement etc. Contrasted with a very gloomy US. And it's been
00:21:32
written that a lot of young people therefore were very
00:21:34
attracted to the Beatles because they were offering an
00:21:36
alternative emotion to the doom and gloom that was sort of in a
00:21:39
lot of parts of the US.
00:21:41
And the Beatles come out, jolly mop tops, hair going ooo, etc.
00:21:44
And that led to the whole British invasion of music bands
00:21:47
and it changed the world of pop music, changed the world of
00:21:50
music and probably changed society a lot. So there is quite
00:21:53
an amazing sort of, you can follow a social thread that
00:21:56
might be an impact of the JFK assassination, apart from a lot
00:21:59
of conspiracy thinking about how terrible governments are.
00:22:02
They have found stuff which indicates the CIA were pretty
00:22:04
crap at preventing it, that they had some information, but they
00:22:07
didn't do a very good job of acting upon it. So they kept it
00:22:10
back for that reason, so as not to be embarrassing.
00:22:11
That's Tim Mendham from Australian Skeptics.
00:22:30
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