# All Questions

7,239 questions
76 views

### Could pure iron from a star make it to Earth?

Since iron is a stars waste could a star that goes Super nova eject pure iron to travel across the galaxy? https://space.stackexchange.com/questions/35101/99-99-pure-iron-meteorite
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### Pictures of galaxies, nebulae: which way is up?

We are used to viewing pictures of the Earth and the planets with their North Pole pointing towards the upper portion of the photo. But when a space telescope snaps photos of cosmic entities, do they ...
62 views

### Why do these Hubble images of Neptune look like Cheela?

The open access paper Formation of a New Great Dark Spot on Neptune in 2018 (cited in Gizmodo's Formation of Dark Vortex on Neptune Captured For the Very First Time and Phys.org's Hubble captures ...
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### Earth orbit around the Sun and its position in the Galaxy

Given the orbit of the Earth around the Sun and the position of the Sun in the Galaxy, in which season are we (the Earth) closer to the galactic center?
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### Adjective for things outside our solar system

I know we have "exoplanets" etc. but those are nouns for specific objects outside our solar system. We have extraterrestrial for objects outside Earth's atmosphere, but I don't know if we have a ...
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### What will be the temperature on Earth when Sun finishes its main sequence?

We know that presently Sun is 4.5 billion years into its main sequence. It has another 5 billion years before it enters the Red Giant phase. We also know that Sun's luminosity increases by 10% every ...
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### How strong are the Lagrange Points of Earth?

How strongly are objects bound to the Lagrange points of Earth that they inhabit in them in the same way Jupiter's Trojan meteors are entrapped in its Lagrange points? In the co-moving frame with the ...
51 views

### How to calculate the thickness of the ice crust on a frozen ocean planet/moon?

How do I calculate the thickness of the upper ice layer on cold ocean worlds like Europa, Enceladus, Ganymede, ...? I'm asking this for a programm I'm currently writing. Given/Known is: mass, radius, ...
103 views

### How much helium has been created since the Big Bang?

When I try to find figures for the amount of helium today and just after the Big Bang, I get similar figures. I was expecting that all of the stars since then would have created more helium. Is the ...
72 views

### What pole is closer to the galactic edge? [duplicate]

Suppose 2 spaceships leave from the earth's north and South Pole going straight up which one will exit the galaxy first (assume they have the same speed and are going in a totally straight line) ? ...
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### What is the lyman-werner background?

I've seen several papers that discuss the Lyman-Werner Background (LWB) when modeling star and galaxy formation in the early universe. One in particular (https://arxiv.org/abs/1803.04527) even varies ...
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### What orbit is the smallest or takes the least time to complete?

What orbit in our solar system would take the least time to perform 1 orbit? What is the fastest possible orbit to complete in the universe?
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### What's fixed in Ariel that is moving in other planet-hunting space telescopes?

The BBC News article UK will lead European exoplanet mission says: Steady platform And one aspect that would work in Ariel's favour is the absence of any moving parts in its build, commented ...
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### Would an X-ray-based pulsar timing array in orbit or on the Moon to study GW background be effective?

This is a follow-on question to Can't pulsars and stars be used for gravitational wave measurement? and the helpful answers there. The Wikipedia article subsection Pulsar timing array; Active and ...
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### Fast moving object like stars in the sky some time two in row but not moving in a straight line [duplicate]

I saw a fast moving object like a star in the sky moving but not in straight line. The brightness of it is like the yellowish normal lights in our streets but not as the colour of the twinkling stars
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### How could a supernova seed solar nebula?

If the heavier elements such as Uranium came from a supernova, then this supernova had to sit somewhere right in the middle of the original solar nebula, because although the ejected matter traveled ...
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### Why is the core of Earth in a reduced state? ($\text{Fe}$ and $\text{Ni}$) [migrated]

I understand gravitational differentiation caused the layered structure of Earth when it is still molten. However, why are the heavier constituents in a reduced state, i.e. metal $\text{Fe}$ and \$\...
90 views

### Sunset on [Mountain] from [Viewing Point]

How do I get the days in this year when the sun will set exactly on top of Fuji as viewed from Enoshima. I shamefully admit that I just want to take a nice picture of Fuji.
112 views

### Can't pulsars and stars be used for gravitational wave measurement?

Suppose that we collected photons from a distant star, and they arrive regularly at 15 photons every microsecond onto a CCD, when a gravity wave bends space time, wouldn't the regular 15 photons graph ...
70 views

### What is the organic material in Saturn's rings?

The phys.org articleSurprising chemical complexity of Saturn's rings changing planet's upper atmosphere about the chemical complexity of Saturn's rings, quotes a member of the INMS (Thomas Cravens) as ...
194 views

### What's the object in the sky?

Days before, I saw this pic. I don't know what it is. Edit: This pic was taken by a Taoist at an ancient ruins in Mongolia on 2012-07-15 04:12 UTC+8 (day break). He said it looked strange. Edit: I ...
5k views

### Why does the Sun have different day lengths, but not the gas giants?

The Sun's rotation period varies from about 25 days at the equator to about 38 days at the poles. As I understand it, this is because the Sun is not solid, and because of the way centripetal force ...
104 views

### As the Universe expands, do things like planets expand also, or just the space in between?

Just what the question says. As the universe expands, and space expands, do objects like planets ever expand? Does the space INSIDE of those objects expand?
137 views

### How is this the last supermoon of 2019?

Media coverage of the "super worm equinox moon" (*eyeroll*) has stated that this is the last supermoon of 2019. Since supermoons normally happen every three or four months, how can there be big gaps? ...
34 views

### How to “slice” a fits table in astropy?

I have imported my fits table, hdul0, into python. I'm using astropy.table. I opened it with hdul0 = fits.open('filename'). hdul0data = Table(hdul0[1].data) I ...
4k views

### Why do astronauts move so slowly in zero gravity? [closed]

When astronauts are floating about in a spaceship or space station, they nearly always move very slowly. After doing a bit of research I can't see why being in zero gravity would restrict movement to ...
55 views

### What's wavelength of the hydrogen atom determines the speed of the gas orbiting at the outer edge of the Milky Way?

The 21-cm spectral line emitted by the hydrogen atom is used to study the structure of the Milky Way because the wavelength is too long to be blocked by the dust in interstellar space. What ...
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### Are gravitational waves part of dark energy?

Do the current models of the universe consider the energy release of gravitational waves? E.g. iirc, the last black hole merger detected had a gravitational wave energy equal to ~3 solar masses (hope ...
38 views

### Was NASA's 2007 attempt to see helions during a solar eclipse successful? What instruments were used?

This answer about Sun-grazing comets led me eventually to Wikipedia's Helion (meteoroid), which has a one-sentence long article: A Helion meteoroid is a meteoroid that arrives from the approximate ...
5k views

### What (the heck) is a Super Worm Equinox Moon?

Google News feed shows me the following. What does the term "Super Worm Equinox Moon" mean and has it ever been used before this 2019 clickbait instance?
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### Seeing a line rather than a dot when looking through refracting telescope

I bought an amateur(and rather cheap) refracting telescope and while I can see moon quite clear and crispy I am having difficulties in observing some larger stars. All stars appear as lines rather ...
69 views

### What is the closest an asteroid or comet has passed the Sun and survived?

After SOHO began watching the Sun from space with its coronagraphs 24/7 it was discovered that there are comets passing very close to the Sun quite regularly, and while some are destroyed, some are ...
99 views

### What is the highest angle the moon ever makes above the horizon at the North Pole?

The question is in the title. I'd like to find out the maximum angle the moon ever makes above the horizon at the North Pole. By "the horizon at the North Pole," I mean the tangent plane to the earth ...
82 views

### Looking at the Expanding Universe through the lens of relativity [closed]

The basis and most observable metric for how the universe is understood to be expanding at an accelerating rate is the red shift in observable light. I am assuming it has been thought about or maybe ...
22 views

### What could be observed with LOFAR in 230 MHz - 10.0 MHz wavelength?

Nuclear astrophysics greatly interests me and i was wondering if there is something that could be observed with the LOFAR project in this wavelength that would benefit the field? Also some general ...
98 views

### If FTL travel is possible can i look back in time to a younger earth? [closed]

For this question assume that. We found a way to go faster than light. I build a ship that could go faster than light and go to another planet with this ship in the span of mere hours. The ship was ...
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### How far out would we need to travel to measure the “constant observer”?

One hypothetical tenet of much astrophysics is that the Universe is uniform on large scales. This actually hinges on many deep theoretical results from astrophysics, since what we actually observe is ...
3k views

### Why doesn't the fusion process of the sun speed up?

Am I correct in saying that the fusion process of the sun is constant, i.e. X amount of fusion happens per day, more or less? Why does this not speed up, i.e. one fusion event creates energy for two ...
24 views

### Can galaxy formation process explain Tully-Fisher relation in dark matter theory?

I read that, unlike MOND theory, Tully-Fisher relation is believed to result from galaxy formation in dark matter theory. What is the exact current status regarding the explanation of Tully-Fisher ...
53 views

### Radiation from Neutron Star impact?

As I understand it, objects falling into an old/inactive/dead/non-pulsar neutron star would be ripped apart, form an accretion disc and eventually emit a burst of radiation as they fall onto the ...
108 views

### What natural mechanisms could lead to the unlikely case of the same rogue asteroid or planet passing through our solar system twice?

I find he following answer to the question What's the soonest Oumuamua could return? unsatisfying and oversimplifying and the last five words "Therefore it will never return." unsupported at a minimum....
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### Did the International Space-Earth Explorer detect cosmic rays other than gamma rays?

In looking at the available datasets described by NASA for the International Space-Earth Explorer, I am only see gamma ray burst data. Was the platform capable of recording cosmic rays other than ...
39 views

### Does Mars' “Northern ocean” have another name? What about the “Inland Sea”?

The March 15, 2019 Phys.org article A NASA spacecraft may have explored the edges of an early Mars sea in 1997 shows a stylized map of an area on Mars where the Mars Pathfinder landed and uses colors ...
81 views

### Why does gravity make time go slower and warp light?

I know that objects with lots of gravity are capable of warping light or slowing time (an example being a black hole). I also know this is because of the theory of relativity, but I need someone to ...
4k views

### Why are there no stars visible in cislunar space?

It’s very puzzling that the moon landing had no stars in the background, the ISS clips have no stars in the background. I listened to multiple astronaut interviews speak on what it looks like up in ...
90 views

### How far does the Earth travel around the Sun during each month of the year?

After reading about the Earth's orbit and how it moves faster in January than it does in July (based on its distance from the Sun), I started to wonder... How far does the Earth travel around the Sun ...
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### How to understand this multi-day exposure photograph of Jupiter and the Moon

This answer includes a stunning photo of the Moon and Jupiter "Trails of the Shifting Moon" by photographer Jin Lu. The caption reads: From the photographer: "I spent 4 days capturing the trail of ...
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### What's the soonest Oumuamua could return? [closed]

Oumuamua is apparently a cigar-shaped asteroid that recently passed through the solar system on an unusual orbit, exhibiting unexpected acceleration. Oumuamua is known to have fairly minimal powers ...
25 views

### Do neutron stars have something like a gamma-ray photosphere? Are gamma rays from below it limited more by the nuclei or electrons?

@RobJeffries' answer to Is there evidence of super-heavy elements in the x-ray and gamma-ray spectrums of neutron stars? includes the sentence: However, the only things that contribute to a neutron ...
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### Is there evidence of super-heavy elements in the x-ray and gamma-ray spectrums of neutron stars?

It occurs to me, that between the surface and interior of neutron stars, gravitational pressure might produce super-heavy elements and that signatures of such elements might be detectable in the star'...

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