Astronomy and Cosmology

Assuming 3i/Atlas is experiencing a deceleration 0,00000002 m/s², would its detection be unavoidable?

Modern physics is CPT symmetric, requires eternalism/Einstein's block Universe philosophy of time - assuming our Universe will finally collapse, the situation before such Big Crunch (BC) seems quite similar to after our Big Bang (BB). It brings many questions (yellow), maybe also answers - I would like to propose to discuss. For example: 1) From entropy perspective, thermodynamical parameters like densities seem very similar near BB and BC - so shouldn't the final entropy be similar? But if so, it means finally entropy should start decreasing - does it mean reversed 2nd law of thermodynamics near BC? How would evolution backward from BC differ from evolution forward fro…

What effects on Earth would we see if its orbital velocity was balanced with Jupiter's gravity at Moon distance to maintain a stable orbit? Assume everything is as it is now and we suddenly found Earth in that situation.

Is there anyone on here that can help me?

Is anyone else following the apparent discovery of objects in Earth orbit pre 1957 by Dr. Beatriz Villarroel while looking at old astronomical photography plates from Mt Palomar Observatory? It would appear that several objects were photographed by the Mt Palomar telescope in 1952 that appeared to be in Earth orbit https://www.researchgate.net/publication/394040040_Aligned_multiple-transient_events_in_the_First_Palomar_Sky_Survey These transient events are difficult to explain, I will post a youtube video explaining these transient events you can watch if you want. https://www.youtube.com/watch?v=MsV9wI4J2ic https://www.reddit.com/r/Astronomy/comments/1mjpa5k/aligned_…

State of the PlanetWas It an Alien Spacecraft—Or a Delivery Truck?A Harvard astronomer says a meteor came from beyond our solar system. A new study questions whether his data includes a more obvious explanation. While even the U.S. Space Command agreed the object was probably interstellar, many scientists doubted that Loeb had really found its remnants, much less that it was something made by aliens. Among them: a group of planetary scientists led by Benjamin Fernando of Johns Hopkins University. They decided to look into not the spherules themselves, but the earthquake record. For this, they recruited Göran Ekström, a seismologist at Columbia University’s Lamont-Doherty …

Greetings Astronomers, This may be an old subject but could you help me understand. Does this article suggests that dark matter is no longer dark? This article suggests that the baryonic gas found among the intergalactic medium--the space between galaxies--comprises 79% of our universe's missing matter. Am I reading that article correctly?

Let's discuss this.

I've done my own version of a diagram of Titan's hydrological cycle (attached,) the original (also attached) being on p12 of Dr Ralph Lorenz's great book Saturn's Moon Titan: Owners' Workshop Manual. Can anyone take a look and see if I've got it right please? Im particularly concerned about what I've put in the big text box about what happens to methane diffusion when it's hit by UV rays. Looks like H2 and H escape to space, and other components are broken down and fall back to the surface, but I'm not sure. It's for a graphic design project Cheerz GIAN🙂XXX (SCIENCE AGE ABOUT 12)

How did Mars lose its magnetic field? Is it due to external changes or are there other possible reasons?

How exactly does the expansion of space result in the lengthening of the wavelength of a photon? So you have a tiny photon in superposition with regards to its position and momentum travelling through spacetime for 13 billion years. An excitation propagating through the EM quantum field. Presumably the field is stretched by expansion, but the photon at any moment is a point. So how do the properties of the photon get stretched when it is just a point in the field? Unless the photon isnt a point, and is a line? And if it is a line, then space expansion doesnt occur at any instant but rather over a period? If a volume experiences space expansion, how do you measur…

Astrophysicists unveil biggest-ever 3D map of Universe: The map is very isotropic and homogeneous, the large scale galactic filaments are not as apparent on this scale. Discussion? Isotropic: .(of an object or substance) having a physical property which has the same value when measured in different directions. .(of a property or phenomenon) not varying in magnitude according to the direction of measurement. Homogeneous: .of uniform structure or composition throughout. Reference: https://www.ctvnews.ca/sci-tech/astrophysicists-unveil-biggest-ever-3d-map-of-universe-1.5030682

A deep field view from Webb, just click on the link in the article and zoom in and out, the small screen bottom right tells you where you are. You can also adjust filters. https://phys.org/news/2025-06-largest-universe-revealing-ghttps://cosmos2025.iap.fr/fitsmap.htmlalaxies-early.html Link here if you prefer not to read the article. https://cosmos2025.iap.fr/fitsmap.html

I've annotated this diagram by Dr Ralph Lorenz about the hydrological cycle on Titan. Does it look right? CHEERZ, GIAN🙂XXX (science age; 12)

I have wondered, if the reason gravity doesn't work at the quantum scale, is bc the shape of spacetime at that scale, is essentially flat/shapeless.

Hello, I'm new to this forum and eager to discuss a preprint paper I recently uploaded to ResearchGate. The paper, titled Fractal Topology of Spacetime, explores a scalar cyclic model and is approximately 17 pages long with a word count of around 7,000. Since it has not yet undergone peer review, I would appreciate any insights or constructive feedback. Would it be appropriate to share the full text here, or would posting a link to the paper be preferable?

I am about to start general astronomy at my college, any suggestions on what to prepare for or any tips regarding the subject?

ok.. someone help me understand this some scientists state some light the detect is from just after the bigbang, and has taken around 13 billion light years to reach us i understand that, but surely that light must have hit something inbetween?

This is something I can't figure out. Why don't they add a module that has a big centrifuge so the astronauts can work in 1G gravity? Or at least they can sleep and recreate in 1G. The ISS is like a big tinker toy where modules of all shapes and sizes can be attached. Why not attach such a centrifuge?

Hiya , I am new here and have been considering shapes . Recently I considered the Suns shape and its apparent roundness . I then considered movement of the Sun and thought to myself if it was moving then how can it retain being a round shape . My question to you all is, If the Sun was moving , wouldn't the shape not be round ?

Are you aware if the apparent superluminal velocities observed with relativistic jets from quasars is a settled issue as being caused by the angle of observation? I have heard that this explanation is disputed, but that was some time ago. Is it settled now?

although i have no idea what this potential stellar engine might look like, i do have a reason to believe we can harness energy from black holes (and subsequently use said energy) using stellar engines. ways of gathering energy from black holes include hawking radiation and accretion disks. i call this potential megastructure a nihility propulsor. thoughts? could this work in theory?

Why is blue shift not called violet shift? I never got the reason, I realize it's possible that there is no reason other then it's easier to say, but I would love a solid answer. Red and violet are at opposite ends of the visible light spectrum, it would make sense to call it violet shift instead of blue shift. Now here's where you make me feel like an idiot because I'm worrying about such a trivial thing.

The Jeans instability is the collapse of a cloud of gas or dust. Recently, a vSauce short claimed that if you wanted to destroy the Sun, you would need to spread its material far enough that it wouldn't recollapse into a star again. vSauce gives the number at 10 AU (Astronomical units) I usually trust vSauce but I have no clue how he got this number and I can't find any additional sources supporting it. Is 10 AU correct? Jeans instability - Wikipedia How To Destroy The Sun

We know that the Earth is protected by a magnetic field that channels dangerous solar wind to the poles, causing the Aurora Borealis. But what about the magnetic poles where this solar wind is impacting the Earth? Is it dangerous for people or animals to spend an extended period of time at the poles, because of the channeled radiation? I asked ChatGPT this question, and here is the answer. Is ChatGPT wrong? "The Earth's magnetic field does channel the solar wind — a stream of charged particles emitted by the Sun — toward the polar regions, leading to phenomena like the auroras (Aurora Borealis and Aurora Australis). However, this …