# All Questions

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### What mechanism causes oscillations of the solar system's orbit about the galactic plane?

In a recent paper (news release here) Lisa Randall and Matthew Reece propose that a dark matter disk coinciding with the galactic plane together with the solar system's oscillations through the ...
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### Why can primordial tensor perturbations of the CMB be ascribed to gravitational waves?

Why can primordial tensor perturbations of the CMB be ascribed to gravitational waves? Is this attribution unique, or are there other michanisms that could lead to the ecitation of tensor modes? In ...
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### If I have amateur astrophotography image data that might be of scientific value, what should I do?

I have some image data that may be interesting to someone, somewhere, but I don't know who to contact or notify. I would imagine it would depend on the type of data, but maybe there is a central ...
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### Why does time get slow near a black hole? [closed]

Why exactly does time get slow around a black hole? And does it provide a way to go into the future?
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### Is there online data on asteroid axial tilts?

I am hoping to find axial tilts for asteroids and also their spring and fall equinox. Some of the asteroids I'm interested in are: 4 Vesta, 1 Ceres, 24 Themis, 65 Cybele, 153 Hilda, 624 Hektor
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### What causes Earth's gravity? [closed]

Why Earth is like a magnet? how can earth attract any object irrespective of what it is made of? What is the reason behind Celestial Body's gravity? i.e Sun,Jupiter,Moon etc.
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### What exactly does outer space contain?

Does outer space contain any gases? Recently i watched a video on youtube,in which NASA installs a camera on a spacecraft.The footage shows some dust particles or some matter floating over the space ...
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### Why are most planetary orbits nearly circular

In our solar system, with the exception of Pluto all planets follow a relatively circular orbit around the Sun, at the same inclination. They also all rotate in the same direction, none are ...
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### need data-point: actual counts per second with APD (avalanche photodiode) detector

I'm designing a sensor system to perform specialized [astronomy and space-sciences] experiments, and need a "reality check" to support or adjust my theoretical calculations. What I need is the ...
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### local stellar mapping data

I've been playing around with Near Star Map, and I think I kind of want something more sophisticated, so for all stars within 100ly/30pc, is the following known? velocity (it would be nice to have a ...
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### Max. speed that a space probe can communite with the Earth? [closed]

Question: Which is the average or maximum speed of a telematically sent message that a space probe can send? Is as simple as radio waves travel at the speed of light in a vacuum? Context: I have been ...
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### Is there another explanation, apart from the doppler effect, for the redshift observed in distant galaxies?

On episode 10 of the original Cosmos TV series, Carl Sagan mentions that some scientist don't agree that the redshift observed in distant galaxies is evidence of the big bang, stating that probably ...
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### Do the E and B modes of the CMB polarization have anything to do with electric and magnetic fields?

As explained in this article, as the CMB is created from a vaiable (matter?) density $\kappa$ its gradient $\nabla \kappa = \vec{u}$ can be separated into a gradient and curl part, called the $E$ and ...
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### What are the differences between TESS and PLATO exoplanet telescopes?

Within a year now it has been decided to launch TESS in 2017 and PLATO in 2024, space telecopes of NASA and ESA. They seem to have very similar science goals, both searching for transiting Earth sized ...
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### regarding spectral type of a star

consider two stars of the spectral type and subtype, but not necessarily both on the main sequence. Describe whether this information is sufficient to tell you how the stars differ in surface ...
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### Galactic Habitable Zone

Do galaxies have habitable zones the same as stars do? Say in a galaxy with a very active nucleus producing a lot of heat and radiation, would there be a point at which no star's planets could harbor ...
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### Black dwarf binary systems

I know black dwarf stars do not exist yet, and that they are what white dwarfs end up after a long time. The question is really simple: would it be possible to have a binary system in which one of the ...
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### Why do stars become red giants?

Disclaimer: I’m not a career astronomer. I don’t own a telescope. I have no professional credentials. But I do find this stuff fascinating, and I consume all astronomy documentaries I can. So, ...
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### If the Wow! signal was not directed at us, then where?

We probably all know the Wow!-Signal, happened on August 15, 1977. Assume that it wasn't meant for us. What was it pointing at then? The signal at that time came from RA= 19h25m31s ± 10s or 19h28m22s ...
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### Radioactive decay is the main source of the earth's interior heat: fact or theory? [closed]

It's believed the main reason that the interior of the Earth hasn't cooled down in 4 billion years is because of the ongoing decay of radioactive elements that keeps adding more heat than is lost to ...
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### Is the universe expanding faster than speed of light?

The celestial bodies like stars and galaxies are moving away from each other. How fast are they moving apart? Is that speed more than the speed of light?
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### What is the orientation of planetary orbits?

I'm working on a planetary motion simulator. I've been working through the equations anomaly, eccentricity, etc. The one thing I'm curious about is if all the ellipses are oriented the exact same way ...
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### Is it possible to be 'still' in space?

So I was reading this answer about how galaxies are the fastest moving objects in the universe because space is expanding faster than the speed of light. This got me wondering, would it be possible to ...
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### Is Earth's 1g solid surface gravity unusually high for exoplanets?

The surface gravities of the Sun’s planets are all close to 1g, 0.38-2.53 (about a factor of e, by chance). The cloud-top gravity of the gas giants is not too interesting here, but I suppose that the ...
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### How do I calculate the velocity dispersion of a galaxy given an integral field spectrograph?

I couldn't find on the web how to get the velocity dispersion and velocity maps of galaxies from the 3D data cube that I get from the integral field spectrograph.
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### Do solstices and equinoxes shift over time?

Right now, I think the winter solstice is around December 21. Has it always been around this date constantly? Since the earth's axis's 23.45° tilt will be on the exact opposite side in 13000 years ...
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### What will happen to life on Earth when Andromeda and Milky Way galaxies collide?

It is said that, Andromeda and Milky way galaxies are coming close to each other with the speed of approx 400000 km/hours. They will be together in the next 4 billion years. 1> What will happen to ...
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### star atlas with absolute magnitude and spectral type

Is there any star atlas someone recommends? Then for some kind of star with a definite spectral type, we can know its absolute magnitude.
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### The reason behind Big Bang

It always amuse us to research about things around us and we always start our research with a question that - what must be the reason for happening of that phenomenon? As we know that the formation ...
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### Question about the formation of elements

So, elements such as iron, gold, etc. are formed from different types of supernovas, whether it's type 1A or 2. My question is, is it possible that there are elements that are formed that we never ...
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### Is it possible to extend the life of a star?

Is it true that when a star 'runs out' of its fuel, it hasn't really used up all its hydrogen, it still has hydrogen left, but the hydrogen is not at its center where the fusion happens. If something ...
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### Convert orbital elements to positions and velocities

I've written a quick and dirty n-body simulator, but currently it requires initial positions and velocities. I've been looking for a way to convert Keplerian orbital elements to positions and ...
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### Why can't I see Mars clearly?

I just bought my first telescope - a Celestron CDC 1100. It came with a 40mm lens so with a primary focal length of 2800mm the power should be 70x. My problem is that I've looked at Sirius and Mars ...
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### Apogalacticon and Perigalacticon

What is the length of the apogalacticon and perigalacticon of the Sun and Milky Way? The general terms seem to be apoapsis and periapsis. My greatest efforts at Googling have failed miserably. If ...
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### Average rate of supernova x number of stars

If we would take the average number of supernovae per year and multiply that by the number of stars, could we figure out how many years it will be before all stars are gone?
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### Is it possible to create an artificial Black Hole?

I am quite curious about black holes. Once I just thought whether it is possible to create an artificial Black Hole, i.e. an human made black hole. Also explain there formation if it is possible.
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### Earth's gravitational pull on ISS

How do they make International space station to orbit the earth beyond earth's gravity acting on it? We all know that ISS is rotating at an altitude of just 350km away.How could ISS escape earth's ...
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### Do more objects appear on sky in time?

I would assume that, with light from more distant areas in space reaching the earth, we should be able to see more distant (and older) objects. However there's lot of weird stuff regarding the space ...
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### Sattelite's orbit

What is the maximum distance for a satellite to orbit the earth? Does earth's gravity has the impact on satellite? I do know that earth's gravity will never be zero and it's gravity is inversely ...
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### Do telescopes harm while observing sun through them?

I don't know whether we can observe a sun through a telescope. But if we can then will it harm our eyes and if such telescopes exists what is their configuration?
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### What is the speed of light relative to (in space)?

From what I understand the universe is expanding faster than the speed of light and accelerating so that it's possible that a given galaxy: $A$ will no longer be visible to another given galaxy: $B$. ...
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### Locate asteroid in asteroid belt

I was interested in tracking the orbit of 1986 DA. I couldn't find any resource when I looked. Just for fun, so any help appreciated.
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### Asteroids turning out to be Meteorites [closed]

What causes an asteroid to loose control over it's orbit and enter in to another objects atmosphere?
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### State of the stars

This question may sound silly but I'm really not pretty sure whether the stars are rotating or stationary.If they are not rotating what makes them to be stable?
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### Do meteorites streak across the sky in the same direction?

Once while camping with my family as a child we all watched a meteor shower in the summer (in the month of August). All the meteorites streaked across the sky in the same direction. Obviously, this ...
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### How fast is the universe expanding?

I've hear several theories stating that the universe is expanding faster than the speed of light, others claim that the universe expands faster the further away you measure it. Which of this is ...
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### When did the Moon stop?

According to various theories the Moon was created around 4.5 billion years ago. About all of these theories suggest that it was rotating around its axis at that time though. Currently, Moon is at ...
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### How to get the longitude/latitude from solar zenith/azimuth?

How do I get the longitude/latitude from zenith/azimuth? Or how can I position my sun in a 3d application? code extracted from here ...