All Questions

3
votes
1answer
43 views

Moon's path as seen from Earth

As observed from the surface of Earth: Will the moon ever repeat the same path (trajectory)? If yes, what is the period of repetition? And also will the moon cover the night sky with its path ...
-1
votes
0answers
21 views

Counting stars in a given area

Suppose that, at a distance of 50pc from the Sun, there is a spherical cluster of stars (uniformly distributed) of radius 1pc and that the density of stars in the galaxy is 0.14 per cubic parsec. ...
0
votes
0answers
18 views

Underground cave in Mars' Armstrong limit [duplicate]

Can a cave, fissure, volcano vent etc. exist on Mars with in the Armstrong limit and support plant life if light and soil was provided? I am not asking how deep is the Armstrong limit of Mars rather ...
4
votes
3answers
171 views

Why does the Moon appear to be flat?

There's no way around it: when I look at the full moon at night it looks like a mostly flat disc, with at most a bit convexity in the middle. Phases of moon look like a full moon seen through a cut-...
2
votes
1answer
32 views

Where can I find data on Mercury's orbit to fit a model to? [duplicate]

I have a project in which a Monte-Carlo method is used to find the optimal parameters for some model that is fit to a data set. I want to fit a model for the orbit of Mercury using this methods, but I ...
2
votes
0answers
41 views

Why is the moon drifting? Shouldn't orbital decay bring it closer? [duplicate]

I noted that the moon drifts away from Earth a few centimeters each year. However, I'm thinking that the emission of gravitational waves would deter such thing and cause the exact opposite. ...
4
votes
2answers
139 views

A neutron star without a flat surface and an atmosphere?

In the Kurzgesagt video Atoms As Big As Mountains — Neutron Stars Explained they state that neutron stars have an atmosphere that reaches about 10 centimeters above the surface. How is this possible?...
1
vote
1answer
79 views

Why is the moon that special? Is it really a well built coincidence? [duplicate]

I find it funny that the moon is the only object in the solar system to almost perfectly fit the sun, resulting in the spectacular solar eclipses. No other object except maybe a few irregular moons ...
0
votes
2answers
68 views

Are red giants stationary or do they move? [closed]

A friend and I are having a friendly chat about this. They are stars so I'm claiming they still move in orbit.
5
votes
2answers
125 views

How can it be known that Venus does not have plate tectonics?

This answer provides some insight into Venus' surface geology: Water may be necessary as a lubricant for plate tectonics. Whether or not this is the case, Venus does not have plate tectonics. It ...
-1
votes
0answers
12 views

What Would Earth's Mean Surface Temperature Be on Axial Maximum?

Over a 41,000-year cycle, Earth's axial tilt (or obliquity) varies between 22.1 and 24.5 degrees. Both numbers may sound awfully low, but the major benefit that it has for the middle and higher ...
16
votes
3answers
3k views

Official degrees of earth’s rotation per day

What is the official degree to one decimal point please, of the earth’s rotation in one single day. Can it be confirmed that it is exactly 360.0 degrees using official data? Thank you in advance.
2
votes
1answer
55 views

Various moon orbits

Orbits can follow certain patterns, as I am aware. Some include a circular orbit around the bulk of the planet, a polar orbit spinning about the pole... What I'd like to know, for a planet with two ...
1
vote
1answer
60 views

Was is the angle needed to see a glory (a rainbow-like effect) from space off the Earth? [closed]

What positions would the Earth, Sun and viewer need to be to see a glory (a rainbow-like effect) from space? What position would they need to be in to reproduce this picture? Source: Gizmodo (NASA ...
3
votes
0answers
59 views

Why do planets and satellites in the Solar system look so wildly different if they came from more or less the same matter?

First, the planets. We have Mercury, which is rocky, no atmosphere. But then we have Venus, which is completely different: thick atmosphere, very hot, geologically active. Then Earth - blue, full of ...
4
votes
1answer
95 views

Why Venus evolved so differently from Earth?

I read somewhere that the reason why Venus has a runaway greenhouse effect and Earth doesn't is the former's inability to form separate tectonic plates due to slightly higher temperature softening the ...
0
votes
1answer
46 views

calculating stellar visibility

Please could you let me know a (basic) formula for calculating at what time a star would become visible of an evening in clear weather conditions. I presume the formula would involve the stars ...
2
votes
1answer
40 views

Mini disk of a blackhole meaning

What is meant by the "mini disk" of a blackhole? Is it the same as accretion disk? If not, whats the difference? Eg: In the abstract of this paper https://arxiv.org/abs/1806.05697 it is mentioned "...
4
votes
2answers
147 views

Does matter accelerate to the speed of light as it approaches the singularity?

$$v_\mathrm e=\sqrt{\frac{2GM}r}$$ If we understand the escape velocity to be the speed needed to escape from the 'surface' of a gravitational object described by the above equation. It is equally ...
-2
votes
1answer
88 views

Can the Sun pull an iron asteriods in it's orbit into it? [closed]

Can our Sun's magnetic field strengthen in any way in a short period? Can the Sun pull anything trapped in close orbit around it? What would happen if an object in orbit passes over a sunspot for ...
4
votes
1answer
58 views

Have any more “white dwarf pulsars” been discovered or searched for?

Back in 2016, Marsh et al. reported that the binary system AR Scorpii exhibits complex radio signals similar to those observed from traditional pulsars. In particular, pulsed synchrotron emission ...
6
votes
1answer
95 views

Anti matter in Jupiter magnetic field?

My question is based in this Wikipedia article about the Jupiter magnetic field: https://en.wikipedia.org/wiki/Magnetosphere_of_Jupiter Jupiter magnetic field generates plasma and accelerates ionized ...
2
votes
2answers
78 views

When would we detect a tiny meter size natural satellit in a geostationary orbits?

A natural, tiny (meters-size, maybe 10.000kg mass) natural satellite could be trapped in a geostationary orbit. I wondered for quite some time: When and how are we able to detect these satellites? ...
2
votes
1answer
59 views

Making sense of the lomb-scargle periodogram

I am trying to use the periodogram to tell when a signal is periodic or not by following the tutorial for the astropy Lomb-scargle periodogram here. http://docs.astropy.org/en/stable/stats/...
3
votes
1answer
58 views

Tuning radio telescopes

In this paper, Section 2.1, the authors talk about using the ICRF2 to find a tuning frequency in search of the 21-cm absorption (of HI). Since we already know the frequency of HI (1420.40575177 MHz), ...
1
vote
0answers
64 views

Conversion factors for flux

I have a flux value in the infrared band of 8 mJy at a wavelength of 80 microns that I want to translate into X-ray conventional ...
0
votes
1answer
178 views

Is the moon inside earth’s atmosphere? If so, what are the consequences?

Recently, a paper was published claiming that the Earth’s atmosphere extends far beyond the Moon. This has been reported on by a number of news sources and websites, including the ESA, Business ...
3
votes
0answers
39 views

How did the Big Bang occured if before that there was no time? [duplicate]

I am thinking, that if the Big Bang created time, it implies that before the Big Bang there was no time (correct me if I am wrong). My question is that, if there was no time before the Big Bang, how ...
1
vote
0answers
31 views

Higgs field interactions in universe [closed]

Is the Higgs field found everywhere? Is it responsible for our mass, and are we in the Higgs field?
0
votes
0answers
14 views

Did OSO-3 or any other spacecraft or ground telescope record the solar activity that is likely the cause of the May 1967 aurora?

The question What solar event caused massive aurora borealis in the mid 1960's? reminds me again of a stunningly bright aurora that I saw circa 40°N circa 1967, and after reading the comments and ...
2
votes
2answers
75 views

Did I see the dragon capsule on Friday night?

I live just south of Sydney Australia, and I went outside to watch the ISS pass overhead on Friday night. The ISS was following a smaller object easily visible to the naked eye. Sydney time 20.43 or ...
7
votes
3answers
2k views

Can we track matter through time by looking at different depths in space?

If we look back far enough we can see all the origins of the universe, so is it possible, even if not feasible, that we could trace the history of some matter as it moves through space-time? I want to ...
7
votes
0answers
51 views

What percentage of Helium-3 is primordial vs produced in stars

I tried to research but what I found is pretty limited. A very tiny but non zero percentage of primordial matter was Helium-3 or 3He. Stars produce 3He as part of the proton-proton chain but they ...
0
votes
1answer
46 views

Mass of a potential black hole in a binary system

So I've been given the velocity curve, parallax and apparent magnitude of a star in a binary system with what is potentially a black hole. I've calculated from the apparent magnitude and parallax that ...
0
votes
1answer
67 views

How to calculate declination of Moon?

Is there any way to calculate declination of Moon for any day?I'll subtract inclination of Earth on the ecliptic from the result. I'll get Moon's the shortest angular distance from Sun. Thanks for all ...
2
votes
1answer
245 views

Could Mars have oil?

What events could have to happen to Mars (which is thought to once look like Earth) that may have depleted the atmosphere and erase all proof of life ever existing at least on the surface? I know an ...
1
vote
1answer
58 views

What fills the new space created during expansion?

Does it remain void and pushes even more or will virtual particles eventually create normal matter?
4
votes
1answer
59 views

Can a frost line exist around a protoplanet?

The Frost line is the border that marks where volatiles such as water, methane, ammonia, etc. (commonly referred to as 'ices') are able to condense into solid grains in the protoplanetary disk around ...
1
vote
1answer
25 views

Vertical speed vector at which the sun travels to and from the galactic equator

What is the speed of progression of the sun toward and away from the galactic equator during its orbit?
2
votes
0answers
36 views

Definition of the light that is projected by a celestial body/luminary [closed]

I'm creating an application which will simulate the light created by sun or moon on a 3d topographic map of Earth. Something like this: Is there a word or definition for this light/light projection?
1
vote
2answers
87 views

Determine distance from the galactic center in DS9

I have a list of coordinates of black hole/neutron star systems in decimal degrees (ie. {(266.416,-29.009), (266.418,-29.009),...} from DS9 and would like to determine the distance from SgrA* in ...
10
votes
2answers
148 views

What was the first astronomical measurement which demonstrated that “the Earth is surrounded by vacuum”?

The question Who was the first to realize that the Earth is surrounded by vacuum? was closed because some users felt it was answered by answers to a different question in an different SE site: Who was ...
1
vote
1answer
55 views

What causes hot temperature extremes?

Recently I looked into the hottest(and coldest, but in another question) natural places. I find this to be a "cloud of searing gas that is surrounding a swarm of galaxies clustered together five ...
1
vote
0answers
54 views

What causes cold temperature extremes? [duplicate]

Recently I looked into the coldest(and hottest, but in another question) natural places. I discover this to be the Boomerang Nebula, with a freezing temperature of about −272.15 °C. Then I looked at ...
9
votes
3answers
163 views

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 ...
1
vote
2answers
71 views

Terminology for empty space at the edge of the observable universe?

Is there a name for a point at the edge of the observable universe at which there is no visible matter, that appears completely dark? I'm thinking something like "empty space", but that could equally ...
1
vote
1answer
57 views

Is there any positive N on which it's agreed among astronomers that 10^-N is accepted as 0 (zero)? [closed]

Is there any positive N on which it's agreed among astronomers that 10^-N is accepted as, or treated as 0 (zero)? I think one of the sciences that most precision is required is astrophysics. I'm ...
4
votes
2answers
148 views

Where is the North of the Universe

Does it exist North of the Universe? (Which is probably used for determining coordinates of far galaxies.) If so, then where it is? On what is it aligned? (Is it orientated on Earth, Sun, Milky Way, ...
1
vote
2answers
128 views

Why does star formation cease?

The universe is expected to have a time when star formation slowly ceases. However, this seems bizarre as there is always an abundant amount of matter in the Universe. Massive amounts of hydrogen ...
0
votes
1answer
87 views

Scenarios: Abusing a black hole

So a black hole is this large, sphere-blob shaped fluid thing that distorts space and time, making a weird hole in space(even after 5 years, I still don't exactly get what a black hole is exactly and ...

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