Astronomy and Cosmology

Because 75% of stars in our galaxy are red dwarfs, they seem like a good place for life to evolve in their habitable zone. The problem with red dwarfs is they have gigantic flares that would be deadly to life in the habitable zone. Also planets close enough to be in the habitable zone would be tidally locked. What about a tidally locked, earth-like planet? I've never heard this before, but what if life could thrive just out of reach of solar flares? Suppose life could evolve just "over the horizon" of the solar flares? The day side is too hot, the night side too cold, but the margin zone could be just right. The margin zone of such a planet could be habitable, and …

https://phys.org/news/2021-03-accuracy-cosmological-analysis-technique-mock.html Researchers confirm accuracy of cosmological data analysis technique using mock data: Astronomers have played a game of guess-the-numbers with cosmological implications. Working from a mock catalog of galaxies prepared by a Japanese team, two American teams correctly guessed the cosmological parameters used to generate the catalog to within 1% accuracy. This gives us confidence that their methods will be able to determine the correct parameters of the real universe when applied to observational data. The basic equations governing the evolution of the universe can be derived fro…

For example, is earth moving in some sort of direction due to expansion, are the galaxies and other planets movies in a direction at some pace. Thank you in advance!

Fueled by word choices such as the "Big Bang" it was always a temptation to think of an initial event where the Early Universe started from a well defined point and grew into an existing Space. But this, we are told is not what happened and it is said that everywhere is the centre of the Universe . Trying to make sense of this (I suspect it may not be too hard or counterintuitive,moreso that I may be "making a meal of it") can I view the situation as the Universe "expanding into itself"? And,if so is the "space" it is expanding into created by itself and equivalent to the distances between its constituent parts?

Hi everyone. Overview: I'm old but still have an interest in learning stuff. I was going to try and get on an undergraduate or post-graduate course in Astronomy or Astrophysics but circumstances have changed, people have become ill and I won't be doing any of that for... an unknown but long time. So I'm just going to do some reading at home but it seems sensible to use an undergraduate or post-graduate degree as a basis to guide that reading. A Google search for recommended reading lists from major universities offering a graduate or postgraduate course in Astrophysics or Astronomy has turned up very few results. Can anyone suggest a book or two please? …

Source screens. Source links. 1) Perseverance Rover’s Descent and Touchdown on Mars (Official NASA Video) 2) Curiosity Drops in on Mars in High-Res 3) Mars Curiosity Descent - Ultra HD 30fps Smooth-Motion Link to this topic (thread) on NASA forum: Curiosity/Perseverance landing scale comparison contradiction.

There is something very strange about the lighting on the Perseverance landing video. 1) Reflection of the “Sun” on the surface of “Mars” as if from a searchlight (too small bright spot). The height of the device at the time of this reflection hitting the frame is 9.5 km. 2) This reflection should be exactly under the Sun, that is, perpendicular to the surface of Mars, that is, point exactly at noon, but judging by the smooth movement of the shadow (on the separating heat shield) in the northeast direction (diagonally at 13:30), there is some kind of contradiction with lighting. The movement of the shadow over the heat shield indicates the position of the Sun in the sou…

https://phys.org/news/2021-02-supermassive-black-holes-dark.html New study suggests supermassive black holes could form from dark matter: A new theoretical study has proposed a novel mechanism for the creation of supermassive black holes from dark matter. The international team find that rather than the conventional formation scenarios involving 'normal' matter, supermassive black holes could instead form directly from dark matter in high density regions in the centers of galaxies. The result has key implications for cosmology in the early Universe, and is published in Monthly Notices of the Royal Astronomical Society. Exactly how supermassive black holes i…

I've been wondering about the expansion of space and the relation to the pressure of space. After reading about the cosmological constant and other things I had questions that I have been unable to find an answer to. I was wondering if the expansion of space and the pressure of space were related? If they're not then why not? I can't seem to find any information about the measurements of the vacuum pressure over an extended period of time to indicate any change in that pressure. To my way of thinking the pressure should correlate with the rate of expansion.( Assuming the two are related. Which I can't see why they wouldn't be.) I was also thinking that gaining an accepted…

I read somewhere that nothing is unstable.

Why, in spite of modifying Newton's second law, not to modify the Gravity Law? Why not, just for instance, to just consider it having two terms one relevant at planetary systems (proportional to 1/r2) scale and the other at galactic scales (proportional to 1/r)? This could be if each term would have a factor making them neglihible at the other scales something not so difficult to imagine, I think. Afterall Newton didn't know about galaxies dynamics. Is that this cannot be compatible with Relativity Theory?

Hi. Where in the universe is the point all galaxies, planets, celestial bodies are moving away from in their expansive motion ? Is that point consistently the one and only same for all constellations ? Is there any curving/bent trajectory ? Am sorry for the poor wording.

But if the big bang is not infinite in size, then it has a finite size, and even if expanding at a mind-boggling rate with an irregular shape, a center of mass could theoretically be determined. The universe, or multiverse, could be more than a single big bang.

How can we know that nothing travels faster than the speed of light (3 x 10^8 m/s)? If there were certain physical phenomena that could travel faster than light, we wouldn't be able to perceive it, since light has a limited fixed velocity. So, what if dark matter and dark energy are just phenomena that actually travel faster than light and we can't detect them through light wavelengths. We can measure its gravitational effects, but not its emission spectra.

In astronomy, the problem of hidden mass has often arisen. For example, at the beginning of the 19th century, an anomaly was discovered in the motion of the planet Uranus and the question arose whether Newton's law of gravity is correct or there is still a planet in the solar system. This question was resolved in 1846 by the discovery of the planet Neptune. Then an anomaly in the movement of Mercury was discovered, and astronomers began to look for another planet between Mercury and the Sun. She was even given the name Vulcan. But in 1915, Einstein explained the anomaly in the motion of Mercury from the perspective of a new theory of gravity, and the search for the Volcan…

The universe is expanding as observed by cosmological redshift - faster than the speed of light, and the speed of expansion is increasing. How exactly is this reconciled with the speed limit of C? Here is a proposal:http://www.scienceforums.net/topic/66209-the-speed-of-light-and-discrete-notions-of-space-and-time/page__p__675852#entry675852

Newton stated that each object was attracting each other, but Newton could not answer what caused this attraction. Time passed and the great scientist Sir Albert Einstein solved this problem with his Theory of Relativity. Albert Einstein defined Gravity by the concept of space-time, according to Albert Einstein, gravity is a curve in space-time. You may not have understood this very well and perhaps I cannot explain it to you through this blog, so let's do a little experiment first. You can also take this video if you want As shown in the video, Suppose space-time is not like a fabric on which our planet stars, satellites, etc.…

Does space weather affect the space crafts` launches and do scientists check it before space crafts go to space? I know there is such a fact like space turbulence and it can influence a spacecraft, but can space weather?

Hi, I am new to this so please bare with me. I am currently debating a flat earther, and I am unsure how to answer this question accurately. The claim is that the sun cannot be 93,000,000 miles away, as when you view it from a high altitude, the suns arc changes too much. The conclusion is that this must mean the sun is much closer, otherwise its arc wouldnt appear to change to us. I put this down to perspective and explained that if it were 93 million light years away our position would effect our perspective. (I might be wrong there) But I would also like to know if or why this is the case, I havent observed this or been able to. Thanks if anyone ca…

Many apologies for this OP as I'm sure it has been raised many times before. IFF the universe were truly infinite in spatial extent (and I appreciate the 'unknowability' aspect of this), would this imply perforce that whatever the energy density of the earliest moments of the universe, it too would have been spatially infinite? In such circumstances, would GR predict gravitational effects to be compressive, tensile or ... just undefined.?

https://arxiv.org/ftp/arxiv/papers/1605/1605.09187.pdf The Fermi Paradox is Neither Fermi’s Nor a Paradox: Abstract: The so-called Fermi paradox claims that if technological life existed anywhere else, we would see evidence of its visits to Earth—and since we do not, such life does not exist, or some special explanation is needed. Enrico Fermi, however, never published anything on this topic. On the one occasion he is known to have mentioned it, he asked “where is everybody?”—apparently suggesting that we don’t see extraterrestrials on Earth because interstellar travel may not be feasible, but not suggesting that intelligent extraterrestrial life does not e…

I've seen a number of references to space flowing across a black hole event horizon at the speed of light. If space can be lost in this way, what happens to the vacuum energy associated with that space? i.e. Does it increase the mass of the black hole?

Can you name spacecraft that can be used for microgravity missions and experiments? Nowadays it`s rather popular and useful to use uncrewed guided space vehicles for particular missions.

Two cosmological models involving the universe as never having had a beginning and never having an end (eternal), and having no boundaries (infinite) are really interesting me: The Cyclic universe in which the universe has always been (for an infinite amount of time into the past) and always will (for an infinite time into the future) go through cycles of massive expansion and then contraction. Our Big Bang being the last bounce back from the previous contraction and the cosmic microwave background radiation (CMBR) the result of the rapid expansion from the last epoch. The universe of dynamical equilibrium. The universe is not expanding. Redshift has been misund…

https://phys.org/news/2021-01-mars-chandler.html A combined team of researchers from the Jet Propulsion Laboratory, California Institute of Technology and the Royal Observatory of Belgium, has found evidence that Mars has a Chandler wobble. In their paper published in the journal Geophysical Research Letters, the group describes their study of decades of data from Mars probes and what it showed them. Approximately a century ago, astronomer Seth Carlo Chandler discovered that imperfectly round objects (such as planets) sometimes spin off their axis for periods of time. The phenomenon has come to be known as the Chandler wobble, and has been documented for planet …