# All Questions

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### What mass of comet would have to settle into a stable orbit around the Earth, to make it rain in the Middle East for forty days and forty nights?

I'm thinking take the typical temperature of a comet and the heat capacity of ice, equate it with the heat which would be generated within such a body in a stable orbit around the Earth and it should ...
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### Why is the core of a gas giant supported by electron degeneracy pressure instead of nuclear fusion?

After a Sun-sized protostar forms, its core will become denser over time due to radiation. The core eventually gets dense and hot enough for hydrogen fusion to take place. In the late phases of the ...
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### Can I leave a planet without achieving escape velocity?

I know that if you exceed orbital velocity, you will never fall-back to the planet. My question is not about orbits. It's about brute-force propulsion to achieve altitude. I'm using an ...
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### Where is Luna 1? [migrated]

Luna 1 was the first attempt by the Soviet Union to crash land into the surface of the moon but narrowly missed after a programming error becoming the first man-made object to escape Earth's ...
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### How do astronomers detect gases that are in the atmosphere of exoplanets?

Exoplanets are just planets that are located outside our solar system - whether that be orbiting a star or drifting past one. Now, the closest star to us is Alpha Centauri which is just over four ...
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### Does the dust around SMBH's protect habitable planets from jets?

The supermassive black hole in the Milky Way is covered by dust as seen from here. Is it common that SMBH's are covered in dust in their galactic disks? Would that dust absorb and disperse a jet from ...
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### Could the 9th planet be virtual?

Astronomers recently claim that there is evidence for a 9th planet. As far as I understood it, this is mainly based on coinciding orbital parameters of a few Kuiper belt objects. Could the 9th planet ...
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### How to calculate the total flux of a source from a fits file?

My fits file is a spire 250micron image that has data units of Jy/beam . I injected a source into it with a peak intensity 20Jy and fwhm(3,3). How can I calculate the total flux of the source? Please ...
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### Warm and Hot dark matter density profiles

for Cold dark matter, density profiles are well known and easy to find information about - NFW,Burkert,Einasto, and others. but for some reason i couldn't find explicit expressions for the density ...
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### Why do we use FITS format for scientific images especially in astronomy? How is it different from formats such as JPEG, PNG etc?

I am new to astronomy and I found that the telescopic dataset can be stored in the FITS format instead of JPEG. Why do we have a special image format just for scientific images?
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### Which stars do I have to use to join with a line to draw constellation figure?

I continue working on a planetarium software and I want to draw the lines that the draw the constellation's figure: Is there a catalogue or something similar with the stars which are the vertex of ...
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### R.A. and DEC. for Constellation area vertices

I'm developing a planetarium software and I need the R.A. and DEC that represents every constellation area in the sky. I think I only need R.A. and DEC for each vertex. Where can I find it? I'm ...
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### How large could gravitational waves get and what effect could they have on us?

The waves detected by LIGO were basically subatomic distortions of space-time. Could there be much greater distortions closer to a source. Would they become perceptible to a human in any way and what ...
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### LIGO gravitational wave chirp signal frequency

This question is about the LIGO gravitational wave signals' frequency, The signals start from about 35 Hz to peak at about 250Hz, giving evidence of gravitational waves, the question is about the ...
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### “Supernova” is the explosion or the resulting celestial body? Is it incorrect to call the explosion “supernova”?

Sorry for such a newbie question. I searched and read multiples sources about supernova but I'm not completely sure if what is called "supernova" is the explosion, the resulting celestial body or the ...
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### Calculating azimuth from equatorial coordinates

I try to get the azimuth of an object from its equatorial coordinates using this formula: $a = \arctan2(\sin(θ - α), \sin φ * \cos(θ - α) - \cos φ * \tan δ)$ Where φ = geographic latitude of the ...
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### Objects are bigger closer to big masses

I usually heard that on surface of earth time pass slower than on orbit. As speed of light is constant it will not change based on your position or observed position. Then if we have big mass that ...
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### How to orientate a telescope using an accelerometer and magnetometer?

For a project with my astronomy professor, we are hooking up an array of 4 smaller telescopes to observe objects in space together. To do this, we wanted to put an accelerometer and magnetometer on ...
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### Converting ecliptical to equatorial coordinates

When looking for a formula to convert polar ecliptic geocentric coordinates of an object to equatorial coordinates I find various sources that give these formulae (like Wikipedia): Declination \$δ = ...
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### Will the E-ELT use Adaptive Optics at visible wavelengths?

In this recent BBC article I read that the European Extremely Large Telescope or E-ELT is in final design and is planned to be on line by 2024, and that (of course) it will rely heavily on adaptive ...
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### What is a quaternary mirror and why does the E-ELT need one?

In this recent BBC article I read the one-sentence paragraph: "Development on the mirrors - in particular, a very complex quaternary mirror - continues apace." and became interested in the ...
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### Difference in energy released in stellar mass black hole merger and supermassive black hole merger

Super massive black holes are usually millions of times more massive than stellar mass black holes. I have read on SE and over internet that 3M☉ worth of energy is released in black hole mergers (not ...
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### Does Sun speaks Om? [closed]

In india on whatsapp people forwards a pic that shows that Nasa says Sun has a voice and it is ancient om. Is it true or just fake cheating idea of Indian people?
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### Communicating with distant planet with life possibility

So, telescopes are like time machines. If we get an image and data for analysis from a planet say 1000 light years away, we are essentially looking 1000 years back in time. Now, if we notice presence ...
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### What's the name for [the other kind of planet] in a binary star system?

This XKCD what-if talks about rainbows on planets in a binary star system. It points out that there are two types: circumbinary planets, where the planet orbits far from and around both stars ...
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### How can white dwarf form Oxygen ? (Temperature problem)

I’ve got a question about white dwarfs and oxygen. I read in a book that a temperature of 100 million degrees is required to fuse Helium in the core of a red giant. The Helium fuses into Carbon by ...
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### How can neutron stars have gaseous atmospheres?

Neutron stars can have small atmospheres. However, they also have extremely strong gravitationally pulls. Shouldn't the all the gas molecules be drawn to the star's surface, and become solids under ...
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### what is the Exact Distance between Mercury & Venus? [closed]

Can any one tell me what is the Exact Distance between Mercury & Venus?
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### Calculating the Diameter of Jupiter through Image

I was trying to calculate the diameter of Jupiter from a picture I took of it. Here's the information I was able to get that I needed to calculate the diameter: Focal Length of Telescope: 1.2 m ...
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### How close could the Moon orbit to Earth without catastrophic results?

How close could our moon orbit around our planet without causing major tidal disruptions, crashing into orbiting satellites, or other serious problems? In addition, how big would it look in the sky to ...
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### In 31.5kyr, Epsilon Eridani and Luyten 726-8 will be < 1ly close; but how distant from the Solar system?

Greetings! Based on Wikipedia and more precisely this paper, it is said that, in about 31,500 years, the stars Epsilon Eridani and Luyten 726-8AB will "meet" at a very close distance (less than 1 ...
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### How ready are we to deal with a asteroid/comet/giant-meteor on a collision course with Earth?

I keep hearing astronomers saying there are observatories scanning the skies all day and night looking for near-Earth objects, extrapolating their trajectories. My questions are If we were to get ...
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### Planetary orbital resonances

The Kirkwood gaps in the asteroid belt are associated with orbital resonances with Jupiter yet planets seem to prefer resonant locations. Why don't asteroids accumulate near the "Kirkwood locations" ...
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### How many planets does Omicron Persei have?

Omicron Persei is a binary star. I did not find information on how many planets it has and if we can actually determine it currently. However, I do know that most stars have planets orbiting around ...
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### How much heat emanates from the planets after formation?

The 2nd answer to this question by MBR got me thinking about this. Is there some general guideline for residual heat a planet should emit, say 4.5 billion years after formation. I'm defining heat ...
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### Is it possible for the year to have 11 full moons (i.e. the opposite of a blue moon)

A blue moon is so called for when we have 13 full moons in a year. https://en.wikipedia.org/wiki/Blue_moon Is it possible to have 11 fun moons in a year? (Maybe if we included calendar changes, for ...
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### What is the simplest model of the Sun? [closed]

What is the simplest stellar structure model for the Sun? Well obviously a Polytropic model can't describe sun ( for now ). Can Eddington's model describe sun?
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### Does the differences between atomic time and astronomical time affect us? [closed]

Earth's rotational period is about 23h 56m. It means that astronomically one day. Also Earth's orbital period is 365.256 atomic days (24 hours). When Earth completes its orbital period in 365.256 ...
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### Which is the largest planet ever observed?

I don't know much about planets outside our solar system. Do we even know the limit of the size of how large a planet or satellite can be? The largest planet I know of is Jupiter, but could there be ...
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### Astronomy Calculations Tool

I took many images like the following: As many of you may recognise, this is a picture of Jupiter and its four Galilean moons. Using these images, I am aiming to calculate the mass of Jupiter by ...
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### Coincidence with Schwarzschild radius? [duplicate]

I was reading the article for Schwarzschild radius on Wikipedia and I noticed that the article states: The observable universe's mass has a Schwarzschild radius of approximately 13.7 billion light ...
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### Appearance of the Cresent [duplicate]

Does the latitude of your position on earth change the appearance of the cresent like it changes the position of other objects visible in the sky? Does it rotate it?
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### Adverse effects of urban growth on old astronomy observatories? Need article/book

I am looking to get some information on the adverse effects of urban growth/light pollution on the oldest/traditional observatories of the world (europe). Can anyone recommend me books or articles to ...
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### Wavelength-dependent limb darkening of the Sun - need approximations or sample images

I need an approximate analytical expression for visible light limb darkening of the sun viewed at large distance, either as a function of wavelength, or even just a few wavelengths from red to blue. ...
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### How to interprete function value of get_sun in astropy

As I know, spring equinox of 2016 is on 2016/3/20 4:30 GMT. I execute following statements in python: ` from astropy.time import Time from astropy.coordinates import get_sun t=Time('2016-03-20 ...
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### Cosmic events as standard candles

Type 1a supernovae are used as standard candles. Are there other high energy cosmic events which can be used as standard candles. For example, collapse of neutron star into a black hole is also ...
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### Direction Names Within a Galaxy

Are there commonly used names for objective directions within a spiral galaxy? Central and peripheral describe objective directions, because the observer's frame of reference doesn't affect whether ...
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### Can young surface of Venus be caused by early oceans instead of global resurface event?

There is evidence of a global resurface event on Venus: the craters are young and evenly distributed. Is it possible that there is another reason: Venus had a very deep ocean in the past, and that ...