# All Questions

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### Is there a database for stars? [duplicate]

I'm interested, is there any database of stars which I could browse on the internet? It would be good, because I could read their parameters, features and maybe find a picture about it. Thanks!
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### Is a supernova's core temperature absolute zero just before collapse?

I thought a supernova's core temperature was absolute zero just before it collapsed, as it has run out of all nuclear and thermal energy, but I haven't been able to confirm this online anywhere and I ...
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### How massive does a main sequence star need to be to go type 1 supernova?

We know the mass a white dwarf needs to be. That's well defined by the Chandrasekhar limit, but before a main sequence star turns into a white dwarf it tends to lose a fair bit of its matter in a ...
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### When the sun explodes, will some of the planets in the Solar System survive and become rogue planets?

Say if a large enough star, that has a number of planets, were to explode in a supernova: Would any of the planets survive? Would they become rogue planets?
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### Why can't this be the simple (and obvious) explanation for the dimming of KIC 8462852?

Couldn't it be just a relatively large object, anywhere in the interstellar space between the star and Earth? I mean, look out the window at a far away car or a tree, then stretch out your hand and ...
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### How do rogue planets orbit around stars in other planetary systems?

I got some interesting answers for What would happen if a rogue planet hit one of the planets in our Solar System? But I have seen some documentaries that state that rogue planets from other ...
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### Acceleration in Galaxies Collision

In the far future the Milky Way and Andromeda will collide. As far I know direct collision between large dense objects (black holes, stars, planets, etc.) is unlikely due to the relative "low density" ...
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### What would happen if a rogue planet hit one of the planets in our Solar System?

As their are millions of rogue planets in the Milky Way, what would happen if one hit a planet in the Solar System. For example, if the rogue planet hit Pluto, would Pluto fall in to the Sun due to ...
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### mountains higher than atmosphere

Is it theoretically possible that planets exist with mountains so high that their peaks overtop the planets atmosphere? And which physical laws are relevant for this question? I'm just curious. Thanks ...
168 views

### Does Mars contain more iron than the Earth?

Is the reason Mars is red because its surface contains a lot of iron? (When dirt is red on Earth, it is sometimes caused by a high amount of iron). If so, does Mars contain more iron than the earth? ...
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### What would night sky look like if Earth was made of antimatter

Let's assume that Earth in its current state is suddenly replaced with the Earth completely identical, but made entirely of antimatter. Ignoring meteorites and asteroids which would cause mass ...
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### Is the time lapse considered when estimating the age of the universe?

We say that our universe is 13.7 billion years ago. During the big bang, it doubled at least 90 times in trillionth of a second (as given here), and other topological statements. The question is ...
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### What were the 2 satellites I saw this morning?

This morning at 6:03am Israel time (3:03 UTC) I saw, simultaneously, what appeared to be 2 satellites streaking across the sky directly overhead. If I remember correctly, they were both coming from NW ...
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### How astronomers distinguishes between natural and artificial signals coming from outer space?

How astronomers really distinguishes between the natural and artificial signals? From time to time astronomers detects many signals from outer space and SETI is always trying to find signals that ...
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### Tidal lock of earth and moon

As the Moon is tidally locked to Earth, that means, from Earth we can only ever see one side of the moon. Can we see all the sides of the Earth, from the moon?
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### How much of the ambient radiation on Mars is arriving line of sight from the Sun?

I read a lot about the amount of radiation bodies like the Moon and Mars receive, but it's hard to find information about where the radiation is coming from. It seems to me that it's cosmic radiation ...
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### How does one add false colour to a fits image

I have an exposure of a star field with a small galaxy located near the centre. It is of course a greyscale image. I would like to add colours (realistic) to this image for aesthetic purposes. What ...
193 views

### Theoretically, what is the biggest optical telescope that may exist?

Recently, I read yet another news about E-ELT. It will have 39.3-metre-diameter segmented primary mirror. And I was interested in the next question: Theoretically, what size of the primary mirror ...
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### Is there any other theory, apart from the Big Bang paradigm, which describes the birth of universe? [closed]

The Big Bang theory is the approved theory of the "birth" of Universe. Are there any other theories which can explain how our Universe came into existence?
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### Is antimatter present on Earth?

As we all know, antimatter is present across all of space. Is it also present on Earth? If it is present on Earth then by the interaction of matter and antimatter, why don't we feel the energy around ...
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### What causes objects to become tidally locked?

I'm trying to write a gravity simulation (suns planets etc), and was hoping tidal locking could be one feature demonstrated. Using a simple equation for gravity has produced some interesting results, ...
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### What is the bulk Lorentz factor?

When we are talking about relativistic motions, say from a relativistic jet, what is meant by the term "bulk Lorentz factor", and the bulk speed, $\beta$?
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### Why nuclear fusion is a controlled process in stars?

Nuclear fusion is the main way for stars to generate energy. But we know that nuclear fission and fusion are not controlled, then it causes chain reaction and sudden explosion. But why in the case of ...
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### How much is the zoom of Sun-Pluto eclipse image

The Sun-Pluto eclipse picture was taken from 2 million km from Pluto. At that distance, Pluto will have angular size of just 4'5". Hence this picture must be a zoomed up image. Approximately how much ...
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### What is the cost and benefit of building two identical telescopes?

I suppose that (especially space) telescope costs is dominated by design and development, not by material and manufacturing. So once a telescope has been developed and designed, how much extra would ...
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### Datasets containing KIC 8462852

What datasets containing KIC 8462852 are available online ? I've found only light curve from Kepler survey.
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### Is antimatter also attracted by gravitational field?

As we all know matter is attracted by the gravitational field of black hole. So, my question is: Is there any possibility of a black-hole attracting antimatter? Can you explain how/why please?
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### Can a probe orbit Pluto given Charon's gravity?

Is it possible for a man-made probe to orbit Pluto given its closeness to Charon? The gravitational field interaction of Pluto and Charon is likely to make simple orbit structure difficult for a ...
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### Can New Horizons probe turn back and start orbiting Pluto

New Horizons probe has found astonishing features on Pluto, while the likelihood of making even greater discoveries is remote in further space. Is it possible for New Horizons probe to turn back and ...
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### Size of Sun as seen on Pluto

What would be the size of Sun as seen from surface of Pluto? It obviously depends on the distance and one would expect it to be very small. However, due to different optical phenomenon, the size of ...
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### My question relates to KIC 8462852. What are the orbits and suspected objects or planets that have been noted around this star?

What are the orbits and suspected objects or planets that have been noted around this star? KIC 8462852
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### What is meant by “short lived” in the duration of a planetary nebula?

In this wikipedia article, it describes planetary nebula as "short-lived," but I'm not sure in relation to what? This could mean billions of years in some contexts. How long is short-lived? Bonus ...
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### Conversion of matter into antimatter

Is it possible that the intense gravity of a black hole converts matter into antimatter? Does this mean that matter or energy that goes inside the black hole is converted to antimatter?
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### What is projected separation and how can I make sense of its unit (h^-1 kpc)?

I have been reading this paper on the separation of a binary quasar in which it states: At a projected separation of 8.3/h kpc (Omega_matter = 1), CTQ 839 would be the smallest projected ...
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### relation between azimuth angle of the sun and angle of the shodow

What is the relation between azimuth angle of the sun the bearing of an vertical object's shadow? For example if the bearing of the shadow is 75° can we conclude that azimuth angle of the sun is ...
194 views

### Can a solar flare destroy every electronic item on earth?

I was reading a book about the sun which suggested that a solar flare can destroy every electronic item on Earth. Is this really true and if so, how would it happen? Could we do anything to to prevent ...
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### In what units to quote the thermal Blackbody temperature

Just a quick question relating to the thermal Blackbody temperature of a celestial object. In the c.g.s regime of astrophysics, is it more 'sophisticated' to quote the thermal Blackbody temperature in ...
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### How is it that all planets (and moons) in our solar system are in equilibrium orbits?

Previously, I was told that in order for any bodies to orbit each other for over a long period of time, the orbital period, distance and masses have to be precisely matched such that the bodies won't ...
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### Questions about terminology used for Mars and its moons

I am having difficulty with some terminology: sub-Martian hemisphere of Deimos ... what place on Deimos does it refer to? leading/trailing apex of Phobos ... what place are those? Apex ... in ...
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### Super moon or Super lag? [closed]

On Sep 25 2015 in California, at 8pm the moon was observed between 11 o'clock and 12 o'clock position in the sky. On Sep 26 at 8pm at the same location the moon appeared roughly between 11 o' clock ...
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### Why don't these Clouds show no depth perception in correspondence to the Sun [closed]

The pictures show exactly what my naked eye visualized.What is the cause of this?
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### Does 2 merging black holes necessarily make a quasar?

2 black holes are about to merge to become a larger black hole. Does this mean it'll become a quasar? From what I know, quasars are supermassive black holes or a collective amount of them. So, if it ...
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### If quasars are powered by black holes, why are they so bright?

If a black hole can swallow everything, even light, then how can a black hole power anything, particularly something as bright as a quasar. Why doesn't the black hole swallow the light of the quasar? ...
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### Are all models of ocean planets theoretically cloud covered?

Take for example an ocean planet slightly smaller than the Earth. Let's say it has a planet-wide ocean that is on the average 10 miles deep. Say for argument sake, that there is a molten, rotating ...
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### Moon's negative greenhouse effect?

Using the standard formula for effective temperature of a planet, Venus has T(eff)=220K, Earth has T(eff)=255K and Mars has T(eff)=212K (using albedo for Venus a=0.7, Earth a=0.367, Mars a=0.25). ...
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### Is there a web service providing orbital data of solar bodies (planets, comets, asteroids, dwarf planets)?

I would like to be able to connect to a web-service and retrieve JSON data containing information on current (as of today or so) orbits of planets, comets, asteroids, and dwarf planets in our solar ...
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### Finding a location using the direction of shadow, UT and date approximately

Does anyone know how to find a location by using : the direction of shadow relative to the normal (for example azimuth angle) the Universal time (UT) and date I have a satellite image and I know ...
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### Is Ceres a terrestrial-type (dwarf) planet?

Does Ceres belong to the terrestrial-type celestial bodies?