# All Questions

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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 ...
71 views

### 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 ...
328 views

### 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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### Is the Sun slightly blue in the center? - Wavelength-dependent limb darkening of the Sun

I've slightly modified the title to try to attract some attention. If we call sunlight "white" and limb darkening is a result of seeing deeper at normal incidence and shallower at oblique incidence, ...
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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 ...
86 views

### 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 ...
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### How bad could we reasonably expect a solar flare to impact earth, and what can be done to mitigate the impact?

According to numerous articles, solar flares have done damage to the power grid on Earth in the past: http://science.nasa.gov/science-news/science-at-nasa/2008/06may_carringtonflare/ How bad can we ...
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### Solar Pressure and Gravity

I recently read some articles and pages on Solar Sails, and the possibility of using lasers to propel spacecraft, and I had a relatively outlandish idea. Would it be possible for a star to be ...
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### How long can you be trapped orbiting around a black hole for?

I have a story I wanna write but I want to be sure it's not completely scientifically irrelevant. I know there is black hole modelisation called the Kerr black holes, in which there is a limit ...
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### What would happen to a gas planet if its core mass goes beyond the Chandrasekhar limit?

Hypothetically, let's say we had a gas giant that continued to accrete mass. I've heard that the cores of gas giants are electron degenerate. So if the planet continued to accrete mass and the core ...
2k views

### Is the Earth-Sun distance 1.012 AU?

Wolfram Alpha's query: Sun Earth distance in AU gives: 1.012 au (astronomical units) They definitely use this value in other places too - e.g. Earth-Sun $L_1$ distances from Earth and from Sun ...
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### What is meant by ionization states?

I am going through the theory of saha equation but I am not able to understand the concept of ionisation state? What are ionization states actually?
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### Stars repartitions

I'm looking for the stars repartitions in percent, in the Harvard Classification (from O to M) I have search every where but I found nothing. I'm not looking for exact values, but more generic values....
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### How does large body gravity affect planet formation?

If Jupiter's gravity is what kept the asteroid belt from forming a planet, then why didn't the sun's gravity keep the inner planets from forming?
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### Has Science observed and recorded a stars birth?

Has Science observed the entire process of a star being created when the area of creation was just a void in space? Or is there still missing data that has not been entirely observed and recorded? ...
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### The observation of changes barycenter of the solar system

Is it possible to observation changes in the barycenter of the solar system? There are graphics showing changes barycenter but they are made on the basis of computer simulation (E.g.: here and here). ...
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### Can we measure/detect GR light bending during solar eclipse using ordinary equipment?

Suppose an amateur astronomer finds himself watching Solar Eclipse. He can see the stars around totality. Is Sun's GR effect strong enough for the amateur astronomer to be able to tell that a ...
2k views

### What is the most dense object in the universe?

Inspired by this answer to the question, Why is the Sun's density less than the inner planets?, what is the most dense object in the universe?
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### What is the effect of the axial precession on the orientation of the planet's orbits?

I am working on an online application to visualize the positions of the planets and to calculate their ephemerides (you find it here, but it is not complete yet). I do not have much knowledge in ...
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### Why 2007 OR₁₀ is not a dwarf Planet yet?

Per definition a dwarf planet is: a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic ...
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### Does weight influence Earth's spin? [closed]

If put enough weight on a particular point on Earth's surface disturbing the balance between hemispheres, is it possible that the Earth's spin could change like an unbalanced spinning top?
6k views

### Why is the Sun's density less than the inner planets?

The density of the Sun is $1410~\frac{\text{kg}}{\text{m}^{3}}$ and Mercury's is $5430~\frac{\text{kg}}{\text{m}^{3}}$, but shouldn't the Sun be denser? Because when the Solar System was forming, ...
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### Is there any proof of space being created?

Is there any proof for space being created? Because I guess an explanation for the dark energy (dark = our understanding of it) could be that there is a gigantic amount of matter/dark matter that we ...
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### Reclaimed bodies in planetary formation?

This question on Worldbuilding.SE got me thinking... We currently think that many bodies that condensed during star/planet system formation, many bodies are ejected. I've heard it stated that there ...
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### In a finite universe, what happens when light reaches the boundary?

If a universe is finite and is not expanding at a speed equal to or greater than c, what happens when light or another form of electromagnetic radiation traveling reaches the boundary?
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### Mass limit of planetary ring

Is there a limit to how massive a planet's ring can be? If there is, how does it depend on the mass of the planet, presence/absence of moons, distance to the star or other parameters?
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### View HD images of space in linux [SOLVED] [closed]

I dont know if this is the correct place to ask this. (I apologize if it isnt) I like browsing through large HD images of space(a weird eccentricity I have), but I always have to go to NASA's image ...
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### Population of excited H levels in a Strömgren Sphere

In chapter 2.2 of Astrophysics of Gaseous Nebulae and AGN Ostriker and Ferland claim that, as far as ionization is concerned, one can assume all atoms to be in the ground state in a Strömgren Sphere ...
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### What is the temperature 55 km beneath the surface of Mars?

What is the temperature 55 km (34.18 miles) beneath the surface of Mars? The reason I ask is that I want to know if it might be habitable for a possible future colony if they could dig that deep (...
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### Why aren't people going to The Moon any more? [duplicate]

In 1969 America landed on the moon, and at that time our technology was not as good as it is now. So my question is, we have much more advanced technology than in 1969, so why are we not utilising ...
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### At what depth on Mars would the atmosphere have equal pressure of that on Earth?

I know the atmospheric pressure on Mars is less than that of Earth, and so is its gravity. However, I know that the deeper you go (e.g. in a cave or a hole that is dug), the more atmospheric pressure ...
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### How to make a telescope for viewing planets, moon and DSOs using a convex lens of aperture 100 mm and focal length 200 mm and other lenses at home?

I wanted to make a telescope with DIY things lying around in home. I read up that the aperture was a very important aspect and thus bought a convex lens with 100mm aperture and 200mm focal length, to ...
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### Directly calculating lat/lon of a satellite directly from RA/declination

I have RA/declination values of a satellite and the observer's location in terms of lat/lon. I want to convert the values for satellite into lat/lon. I have tried to use the method which uses ...
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### How come the northern and southern lights are the same?

Not an expert, hence the question. To my knowledge the magnetic field of the earth travels south to north. Wouldn't there be a bias on whether the charged particles causing the auroras are negatively ...
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### How to Calculate Parallax Angle [duplicate]

I understand that parallax "is a displacement or difference in the apparent position of an object viewed along two different lines of sight" - Wikipedia. So, when calculating the distance from the ...