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1500 questions
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What else could the Event Horizon Telescope Observe?
The Event Horizon Telescope was made possible in order to observe the details of supermassive black holes. This took a huge amount of work installing extra telescopes and developing the hardware and software needed to do VLBI at such short…
Steve Linton
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12
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Existence of planets larger than their host star?
The mass region of objects between ~ 0.5 Jupiter masses and 80 Jupiter masses (gas giants through to brown dwarfs and red dwarfs) is typified by an almost flat relationship with object diameter. There are planets out there which are larger in…
Ingolifs
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12
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Why do we see galaxies with their actual spiral shapes?
Since the actual position of stars is relative, and we see the light they emitted long time ago, and one galaxy has thousands of millions of stars, and those stars can be separated by hundred of thousands of light years, why don't we see galaxies as…
Mbbc
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What object in the universe is most opaque to neutrinos?
I had this thought, and my first guess was "high density = lots of absorption, so I guess it's neutron stars" but this physics.se question about that has a great answer which covers why that's incorrect.
So what object will absorb the highest…
llama
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How did they make a video of the center of the galaxy, and what is it exactly that's flashing there?
The ESA video ESOcast 173: First Successful Test of Einstein’s General Relativity Near Supermassive Black Hole includes a clip of images of stars at the center of our galaxy orbiting around SgrA*, a presumed supermassive black hole. This isn't…
uhoh
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1 answer
Mars vs Venus: the retention of atmospheres in relationship to Earth
Correct me if I'm wrong, but the factors than enable a planet to retain or lose an atmosphere seem to be: 1. Magnetic Field, 2. Solar Winds, 3.Weight of Gases, 4. Planetary Temperatures. 5. Distance from the Sun In regards to solar winds and…
Peter Wilson
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12
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After Oumuamua passage, has an "urgency" telescope time request procedure been set up?
During the rapid passing of ʻOumuamua through our solar system, it was difficult to get instant telescope time. Usually, formal requests and a review process are necessary before telescope time is provided to a particular project.
Now everybody is…
Everyday Astronaut
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How would astronomical seeing on Mars differ from that on Earth?
Astronomical seeing is the limiting factor for the resolution of all but the smallest Earthbound telescopes.
Source
Stunning advances in adaptive optics (along with it's predecessor speckle interferometry and it's budget-minded cousin lucky…
uhoh
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Why can't a quasistar exist now?
From my research, I found out that quasistars theoretically existed because of a black hole core whose radiation pressure counteracted gravity within the star. However, a few websites stated that quasistars do not exist now because there are metals…
Pyrania
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Why black holes are extremely cold?
"The most massive black holes in the Universe, the supermassive black
holes with millions of times the math [sic] of the Sun will have a
temperature of 1.4 x $10^{-14}$ Kelvin. That's low. Almost absolute zero,
but not quite. A solar mass black…
Paran
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5 answers
What is the proper interpretation of a negative parallax?
The Gaia data release 2 dataset has some parallaxes listed as negative. What is the proper interpretation of this? Should they be discarded as bad data? Use their absolute value to calculate the distance? Use them as-is and treat them as negative…
shino
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Local Sidereal Time
I am trying to understand how to calculate local sidereal time and have found the following formula:
$$\text{LST} = 100.46 + 0.985647 \cdot d + \text{long} + 15 \cdot \text{UT}$$
Here, $d$ is the number of days from J2000, including the fraction of…
user3574623
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12
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1 answer
Do neutron stars shine?
Ignore pulsars and the like, just a neutron star in empty space – does it emit light and neutrinos?
user6760
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4 answers
Is any 3 body system known?
https://en.m.wikipedia.org/wiki/Three-body_problem
Have three or more celestial bodies rotating each other in a stable manner ever been observed, or it is only a theoretical problem?
user84558
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What is the name of that which exists beyond the Universe?
"The Universe is commonly defined as the totality of existence" but that is more of a philosophical position. Empirically we know (or believe) that it is of finite size some believe it is expanding others that is (or will be) contracting.
As we…
James Jenkins
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