Astronomy and Planetary Science Thread

Earth’s history written in the stars: zircon crystals reveal galactic influence

New Curtin University research has uncovered a striking link between the structure of our galaxy and the evolution of Earth’s crust, showing its development was shaped by the impact of meteorites during its journey through the Milky Way and not solely through internal processes as was previously widely considered.
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www.curtin.edu.au

Earth’s history written in the stars: zircon crystals reveal galactic influence | News at Curtin

New Curtin University research has uncovered a striking link between the structure of our galaxy and the evolution of Earth’s crust, showing its development ...
www.curtin.edu.au www.curtin.edu.au

Related paper:

 
Hmmm, hadn't heard of the details of the penetrator technique before. The method is to get the energy into the body of the asteroid. If it's a relatively small one, use a massive tungsten penetrator that melts as it penetrates the body and thus transfers its energy into the mass of the asteroid, heating far more of it than an external nuclear explosion would. Faced with a planet-killer, use a series of penetrators to dig a tunnel into its heart and then send a big nuke to follow.

Inspired by 'Rods from God' obviously.*

Does anyone know any more about this idea?

View: https://www.youtube.com/watch?v=dKm7T13X7n4


*https://en.wikipedia.org/wiki/Kinetic_bombardment
 
That would unfortunately still send chunks of broken asteroid our way if they even attempt to do it in a real emergency when a city killer sized asteroid was to hit Earth, it would end up being like what was fetured in the film Deep Impact.
 
FighterJock said:
That would unfortunately still send chunks of broken asteroid our way if they even attempt to do it in a real emergency when a city killer sized asteroid was to hit Earth, it would end up being like what was fetured in the film Deep Impact.
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Yep. The best solution is still gigaton-range nukes, backed up by X-Ray lasers and other heavy duty weaponry.
 
The lasers would have to be rapid firing to cope with the amount of rubble that would come of the main explosion not the COIL lasers that were used in the airborne laser.
 
Grey Havoc said:
Yep. The best solution is still gigaton-range nukes, backed up by X-Ray lasers and other heavy duty weaponry.
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Make more sense to put Orion Puls engine on big Roid and use Nuke to alter the course of Roid away from Earth...
 
Michel Van said:
Make more sense to put Orion Puls engine on big Roid and use Nuke to alter the course of Roid away from Earth...
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One issue with that is that you would likely need to more reliably detect potential impactors well in advance in order to be able get to and maneuver them away in time.
 
The measured rotation period was consistent with the spot position shifts inferred from the transit observations, enabling the team to obtain a unique solution for the system geometry. They found that the stellar spin axis and the planet’s orbital axis are misaligned by about 62°, revealing that TOI-3884 is a highly tilted planetary system. Such large tilts are typically attributed to past gravitational interactions with massive planets or stellar companions—yet no such companions are known to exist, making this system particularly intriguing.
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Here's an interesting video from Anton Petrov concerning the slipperiness of ice:


Hello and welcome! My name is Anton and in this video, we will talk about new study that challenges 200 years of physics about why ice is slippery
Links:
https://journals.aps.org/prl/pdf/10.1...
https://www.mdpi.com/2075-4442/6/1/26
https://link.springer.com/article/10....https://www.youtube.com/redirect?ev...ticle/10.1007/s11249-016-0665-z&v=ZhHc3xDNfGw
Other ice videos:
https://www.youtube.com/watch?v=upJxH1cTvVE
• Shocking Discovery That Water Ice Can Prod...

• Bizarre Form of Water Ice Solves a Magneti...

• Experimental Evidence That Water Ice Can B...

• Ice In Space Is a Lot Stranger Than We Tho... https://www.youtube.com/watch?v=BxAvat0PD8g
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0:00 Why is ice slippery?
1:30 What we thought previously - liquid layer
2:50 Pressure melting proposition
3:43 Frictional heating proposition
4:17 Experiments couldn't prove it
5:20 New research using molecular simulations and exciting discoveries
8:10 Evidence from the study
8:45 Unusual findings
10:15 Amorphization, viscosity and surface types
11:40 What all of this means
12:40 Conclusions and what's next
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#ice #water #physics
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FighterJock said:
That would unfortunately still send chunks of broken asteroid our way if they even attempt to do it in a real emergency when a city killer sized asteroid was to hit Earth, it would end up being like what was fetured in the film Deep Impact.
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I gather that some scenarios are based on the principle that a disaster is preferable to a catastrophe and a catastrophe is preferable to an apocalypse.
 
Brett Davidson (Rhino...) said:
I gather that some scenarios are based on the principle that a disaster is preferable to a catastrophe and a catastrophe is preferable to an apocalypse.
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At astronomical speeds, any collision completely disintegrates the projectile into plasma before it pierces too far into the interior of the asteroid, if it is of the NI-Fe type, and completely disintegrates it if it is of the "rubble pile" type

In the first case, the impact would only deflect the trajectory, in the second, most of the pieces would be rejoined by the effect of microgravity.

In my opinion, a bunker-busting nuclear bomb would be more effective in both cases.

https://en.wikipedia.org/wiki/Nuclear_bunker_buster
 
When Jupiter and Saturn were forming I suspect that in their very early stages they quickly went from Super Earths to Ocean planets to mini-Neptunes to Ice giants.
 
At the conference, Coelho was coy about an upcoming piece of news from ARCA and KM3NeT. Nature reports that ARCA has already detected the likely most energetic neutrino to date, and unlike the chill neutrinos created in our atmosphere, this one is probably from something “cataclysmic” in the faraway cosmos. And this is ARCA’s secret weapon: a fourth layer that ignores all the previous noise in order to amplify energetic neutrinos from further away.

At this energy level, Coelho explained, it’s almost always very dark. When many of ARCA’s sensors lit up with an unexpected and very bright event, the scientists all took notice. The energetic neutrino signature seems to have given ARCA a proving ground to continue searching for neutrinos from the cosmos—as well as their explosive sources.
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www.popularmechanics.com

Scientists May Have Found Signs of a Hidden Universe on the Ocean Floor

Deep-sea sensors detected the most energetic neutrino ever recorded.
www.popularmechanics.com www.popularmechanics.com
 
Has anyone else got paranoid about You Tube that when it suggests an astronomy or space flight video to you, and it’s from some channel you’ve never heard of before, that it’s going to be some AI generated slop these days? I just don’t trust You Tube’s algorithms.
 
Some interesting info in this article on observations planned of this comet.

Comet 3I/ATLAS – frequently asked questions

What is comet 3I/ATLAS?

Comet 3I/ATLAS is a newly identified interstellar object, meaning that it comes from outside our Solar System. It is only the third of its kind ever observed, following 1I/ʻOumuamua in 2017 and 2I/Borisov in 2019.

Why is it important?

These comets are absolutely foreign. Every planet, moon, asteroid, comet and lifeform in our Solar System share a common origin. But interstellar comets are true outsiders, carrying clues about the formation of worlds far beyond our own.

When and how was it detected?

It was first spotted on 1 July 2025 by the Asteroid Terrestrial-impact Last Alert System (ATLAS) telescope in Río Hurtado, Chile. Its unusual trajectory immediately raised suspicions that it originated from interstellar space. This was later confirmed by astronomers around the world, and the object was given its formal designation: 3I/ATLAS.

Why the name ‘3I/ATLAS’?

Traditionally, comets were named after the person who discovered them. Nowadays, we follow a coded naming system developed by the International Astronomical Union. The first letter indicates the category that the comet falls under – in this case ‘I’ for ‘Interstellar’. The number ‘3’ before the ‘I’ indicates that the comet is the third of its kind. The word ‘ATLAS’ refers to the programme that operates the telescope that first spotted the comet.
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Can you give some quick facts about the comet?

Size: a few hundred metres to a few kilometres across

Speed: roughly 210 000 km/h – the highest ever recorded for a Solar System visitor

Age: billions of years old – indicated by its breathtaking speed, evidence that it has been drifting through space for a very long time

Closest approach to Earth: 240 million km

Closest approach to Mars: 30 million km

Does it pose a danger to Earth?

The comet will come no closer than 240 million km – that’s over 1.5 times the distance between Earth and the Sun. During its closest approach to the Earth, it will be on the other side of the Sun. It poses no danger to our planet or any other planets in the Solar System.

Is ESA’s Planetary Defence Office tracking the comet?

Yes. ESA's Planetary Defence Office responded promptly to the discovery, with ESA astronomers contributing to global efforts to track the comet’s path using telescopes in Hawaii, Chile and Australia. They are also looking for evidence of its existence in older data – a process known as ‘precovery’.

These efforts are part of ESA’s broader mission to detect, track, and characterise near-Earth objects – though 3I/ATLAS is not considered one, due to its distance from our planet.

By the time the comet reaches its closest point to Earth, it will be hidden behind the Sun. It is due to reappear in late November, offering astronomers another window for study.

What will happen to 3I/ATLAS in the coming months?

3I/ATLAS is an active comet. Observations by the NASA/ESA Hubble Space Telescope already capture a dust plume ejected from the Sun-warmed side of the comet, and the hint of a dust tail streaming away from its nucleus. Comets originating within our own Solar System display similar behaviour.

As the comet continues to approach the Sun, it will likely lose more and more mass as frozen gases transform into vapour, carrying dust and ice into space. Observations by the NASA/ESA/CSA James Webb Space Telescope of the coma, or ‘halo’, surrounding the comet already reveal carbon dioxide, water, carbon monoxide, carbonyl sulphide and water ice being released as the comet heats up.
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Is ESA planning to visit 3I/ATLAS?

The comet will make its closest approach to the Sun in late October 2025, passing just inside the orbit of Mars. After that moment, it will speed away from us. This is far too soon, and the comet is moving far too quickly, to contemplate sending a spacecraft to visit or land on it. Instead, we are observing 3I/ATLAS from a distance with our space telescopes and planetary missions.

What ESA missions will observe 3I/ATLAS?

The comet has already been observed by space telescopes close to Earth, including the NASA/ESA Hubble Space Telescope and the NASA/ESA/CSA James Webb Space Telescope. In the coming months, ESA will turn interplanetary voyagers such as Mars Express, ExoMars Trace Gas Orbiter and the Jupiter Icy Moons Explorer (Juice) in the direction of the comet to make further observations with eyes from all over the Solar System. 3I/ATLAS will pass through the field of view of the ESA/NASA Solar and Heliospheric Observatory (SOHO), but we expect it to be much too faint to be visible.

When and how will ESA’s Mars’s missions observe 3I/ATLAS?

ESA’s Mars Express and ExoMars Trace Gas Orbiter (TGO) will observe the comet with several instruments around its closest approach to Mars on 3 October 2025. On that date, 3I/ATLAS will be around 30 million km from Mars.

The instruments turning their eyes to the comet include Mars Express’s High Resolution Stereo Camera (HRSC) and ExoMars TGO’s Colour and Stereo Surface Imaging System (CaSSIS) – both cameras that are typically used to photograph the Red Planet. We will also attempt to measure the spectrum of light from the comet using Mars Express’s OMEGA and SPICAM spectrometers and TGO’s NOMAD spectrometer, though it is not certain whether the comet and its tail will be bright enough for a full spectral characterisation.

The observations may give us hints about the volatile activity and composition of 3I/ATLAS. As Mars Express and ExoMars TGO are designed to image the martian surface just a few hundred to thousand kilometres below, we do not expect spectacular images of a (relatively) small comet 30 million km away; the comet itself will cover less than a pixel in the images. We expect better images of the halo of gas around the comet and the tail that streams behind it. The success of the observations also depends on how bright the comet is as it approaches the Sun, which in turn depends largely on how much water it contains and how much escapes in the form of a tail.

When and how will ESA’s Juice mission observe 3I/ATLAS?

Of all ESA interplanetary spacecraft, the Jupiter Icy Moons Explorer (Juice) is likely to have the best view of 3I/ATLAS in a very active state. Juice will attempt observations in November 2025 using several instruments, including cameras, spectrometers and a particle sensor. Coordination with NASA’s Europa Clipper mission is being considered, in particular to observe using the twin ultraviolet spectrographs (one on each spacecraft).

As Juice is currently close to the Sun, it is using its main high-gain antenna as a heat shield. It is using its smaller medium-gain antenna to send data back to Earth at a much lower rate. It is also far from Earth, on the other side of the Sun. Therefore, we don’t expect to receive data from Juice’s observations of 3I/ATLAS until February 2026.

Is ESA planning any missions to visit a comet in the future?

Following in the footsteps of ESA’s Rosetta mission, which landed on Comet 67P in 2014, ESA is currently developing the next-generation comet mission, Comet Interceptor. Comet Interceptor will be the first mission to visit a comet coming directly from the outer reaches of the Sun's realm, carrying material untouched since the dawn of the Solar System. It is also possible – though very unlikely given their rarity – that Comet Interceptor could visit an interstellar comet.
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How Interstellar Objects Similar to 3I/ATLAS Could Jump-Start Planet Formation Around Infant Stars

Interstellar objects like 3I/ATLAS that have been captured in planet-forming discs around young stars could become the seeds of giant planets, bypassing a hurdle that theoretical models have previously been unable to explain.
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…

Interstellar objects can potentially bypass this problem. Pfalzner’s models show how the dusty planet-forming disc around each young star could gravitationally capture millions of interstellar objects the size of 1I/’Oumuamua, which was estimated to be around 100 metres long.
“Interstellar space would deliver ready-made seeds for the formation of the next generation of planets,” said Pfalzner.
If interstellar objects can act as the seeds of planets, it also solves another mystery. Gas giant planets like Jupiter are rare around the smallest, coolest stars, which astronomers refer to as ‘M dwarfs’. They are more commonly found around more massive stars similar to the Sun. The problem, though, is that planet-forming discs around Sun-like stars have a lifetime of about two million years before dissipating and it’s very challenging to form to form gas giant planets on such a short timescale. However, if captured interstellar objects are present as seeds onto which more material can accrete, it speeds the process of planet formation up and giant planets can form in the lifetime of the disc.
“Higher-mass stars are more efficient in capturing interstellar objects in their discs,” said Pfalzner. “Therefore, interstellar object-seeded planet formation should be more efficient around these stars, providing a fast way to form giant planets. And, their fast formation is exactly what we have observed.”
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EPSC-DPS2025: How Interstellar Objects Similar to 3I/ATLAS Could Jump-Start Planet Formation Around Infant Stars – Europlanet

www.europlanet.org www.europlanet.org
 
Flyaway said:
Has anyone else got paranoid about You Tube that when it suggests an astronomy or space flight video to you, and it’s from some channel you’ve never heard of before, that it’s going to be some AI generated slop these days? I just don’t trust You Tube’s algorithms.
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Same here. It's happening on my facebook feed too with lots of alerts about amazing new discoveries - such as Morris dancing cures cancer, someone somewhere has been able to generate cold fusion in porridge, poodles are actually insects, kelp is intelligent, and of course the perennial ancient civilisations and/or aliens. The algorithms have discovered that I'm interested in science but they can't distinguish between science and pseudoscience.

en.wikipedia.org

Gresham's law - Wikipedia

en.wikipedia.org en.wikipedia.org
 
Brett Davidson said:
Some or many apparent water worlds or mini-Neptunes might be carbon planets.

View: https://www.youtube.com/watch?v=YhHLGv76Z0U


https://arxiv.org/pdf/2508.16781
https://arxiv.org/pdf/2508.15117
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Follow-on, an alternative model. Sub-Neptune water worlds may just be very unlikely but OTOH, Earth-like worlds with oceans might be fairly common.

Earlier models assumed that sub-Neptunes could accumulate vast amounts of water during their formation, leading to “Hycean planets”—a blend of hydrogen and ocean. But those models didn’t account for chemistry between a planet’s atmosphere and its molten interior.

Caroline Dorn, professor of exoplanets at ETH Zurich, explains: “Water on planets is much more limited than previously believed.” Her team factored in how early sub-Neptunes likely had deep magma oceans wrapped in hydrogen gas. As the atmosphere and magma interacted, water molecules were broken down. Hydrogen and oxygen bonded with metals and silicates, sinking into the planet’s core.

Computer simulations of nearly 250 model planets confirmed this process, showing that only a tiny fraction of water—just a few percent at most—remains on the surface. This makes the idea of ocean-covered Hycean worlds with 10–90% water mass extremely unlikely.

It narrows the playing field. Planets large enough to be sub-Neptunes are probably too dry to support Earth-like oceans. Instead, smaller rocky planets may be better candidates for habitable conditions. Detecting such worlds, however, will require telescopes even more powerful than today’s James Webb Space Telescope.

Interestingly, the study also suggests that Earth may not be unique. Our planet’s modest amount of water appears fairly typical when compared to the simulated results. “Earth may not be as extraordinary as we think,” says Dorn.

Perhaps most surprising, the most water-rich atmospheres didn’t come from planets formed far out in icy regions, but from those that developed closer in. There, water was generated chemically—when hydrogen in the atmosphere reacted with oxygen in magma—to form new H₂O.


www.sciencedaily.com

Alien water worlds were just a mirage

A new study challenges the dream of water-rich “Hycean” planets like K2-18b, suggesting that most sub-Neptunes lose their water deep into their interiors during formation. Instead of vast oceans, these worlds likely retain only a few percent of water at the surface.
www.sciencedaily.com

scienmag.com

Exoplanets: More Than Just Water Worlds

An exoplanet identified as K2-18b, located 124 light-years from Earth, recently ignited interest and speculation within the scientific community and beyond. The excitement initially centered on a
scienmag.com scienmag.com

 
NMaude said:
That magma would cool down eventually forming a deeply buried solid surface so I wonder if water could then precipitate onto it?
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I'm hoping that Planet Nine really exists and that we can get a spectrum of it, and maybe (probably long after I've gone to the big distillery in the sky) a probe to discover its structure.
 
A volcano or a meteorite? New evidence sheds light on puzzling discovery in Greenland’s ice sheet

Buried deep in Greenland’s ice sheet lies a puzzling chemical signature that has sparked intense scientific debate. A sharp spike in platinum concentrations, discovered in an ice core (a cylinder of ice drilled out of ice sheets and glaciers) and dated to around 12,800 years ago, has provided support for a hypothesis that the Earth was struck by an exotic meteorite or comet at that time.

Our new research offers a much more mundane explanation: this mystery platinum signature may have originated from a volcanic fissure eruption in Iceland, not space.
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…

It is important to note that our research focused on the platinum spike and did not consider other evidence, such as spherules (spherical fragments of melted rock) and black mats (mysterious dark layers in soil), for an extraterrestrial impact. That said, based on our analysis of the new results and existing data, a large northern hemispheric volcanic eruption seems to be the most straightforward explanation for the Younger Dryas Event.

Understanding past climate triggers is vital for anticipating what lies ahead. Although the chance of a large meteorite impact or volcanic eruption in any given year is low, such events are virtually certain to occur eventually. Knowing how Earth’s climate responded in the past is therefore crucial for preparing for the consequences of the next major event.
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theconversation.com

A volcano or a meteorite? New evidence sheds light on puzzling discovery in Greenland’s ice sheet

New research suggests that a mystery platinum signature found in Greenland’s ice may have come from a volcanic eruption in Iceland.
theconversation.com theconversation.com

Related paper:

journals.plos.org

A possible volcanic origin for the Greenland ice core Pt anomaly near the Bølling-Allerød/Younger Dryas boundary

The Younger Dryas Event (YDE) is the most recent and most well-understood millennial-scale cooling event. A deglacial meltwater pulse is the traditionally accepted trigger for the event, but both a bolide impact and volcanism are recently advanced alternative explanations. A high Pt/Ir and Pt/Al...
journals.plos.org journals.plos.org
 
NMaude said:
We do have a planet Nine already, it's called Pluto, it's Planet X you're thinking of.
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If Pluto is Planet Nine, Eris would be a candidate for Planet X.
en.wikipedia.org

Dwarf planet - Wikipedia

en.wikipedia.org en.wikipedia.org
A dwarf planet is a small planetary-mass object that is in direct orbit around the Sun, massive enough to be gravitationally rounded, but insufficient to achieve orbital dominance like the eight classical planets of the Solar System.
[...]
dwarf planets – in rough order of decreasing diameter, Pluto, Eris, Haumea, Makemake, Gonggong, Quaoar, Sedna, Ceres, and Orcus.
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Pluto a proper planet? That means any number of Solar System planets from ten through seventeen - or higher, keeping in mind the trans-Neptunian Solar System may hide all kinds of surprises. Well past ten - X - anyway.
 
Arjen said:
Pluto a proper planet? That means any number of Solar System planets from ten through seventeen - or higher, keeping in mind the trans-Neptunian Solar System may hide all kinds of surprises. Well past ten - X - anyway.
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I've heard this tired song and dance before and it could simply be avoided by "Grandfathering" in Pluto for historic reasons.
 
Grey Havoc said:
Handy for a planetside base.
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Given that Venus's dense, highly toxic atmosphere (~95% CO2 with sulphuric-acid aerosols present) has an surface pressure of ~90 atmospheres (Equivalent to under ~3,000ft of sea-water) and a temperature of ~900F (Hot enough to melt lead and zinc). Using those tunnels for a base would be rather....difficult to implement;):D.​
 

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