1
vote
1answer
25 views

What's the difference between the Julian and the Julian Ephemeris Day?

I'm making a code where I calculate the sun position in a given time. But I also want to learn astronomy with it. I'm following a .pdf to make the program, and in this .pdf it says The Julian Day ...
0
votes
0answers
12 views

What is the term for the point between a star and planet where a 3rd object will cast the largest shadow on the planet?

Is there a particular orbital configuration that would allow an object to orbit a planet while casting a stable shadow on a planet in said position? I would also be interested to know if there is a ...
12
votes
1answer
3k views

Is the moon moving further away from Earth and closer to the Sun? Why?

According to The NASA Moon Facts page: The moon is actually moving away from earth at a rate of 1.5 inches per year. Why is the moon moving further away from the Earth? Is this a result of the ...
1
vote
1answer
32 views

accuracy of an artificial satellite at certain magnitude

When we say that 'accuracy of gaia satellite is 10 $\mu$as at $V = 10$ magnitude in position and annual proper motion'. What does this mean. Does it change over time.
2
votes
1answer
26 views

Do magnetic fields affect planetary rings?

Planetary rings seem to generally form on the ecliptic plane because of the rotation of the planet, but I was wondering what kind of effect the magnetic field of the planet might have on the ring ...
22
votes
2answers
2k views

Do all stars have an oort cloud or is it a rare occurance?

Do all stars have an oort cloud like ours that will be filled with comets and other objects? If not, why are they not around every star?
1
vote
0answers
26 views

Equation for solar radiation at a given latitude on a given exoplanet?

I'm trying to find equations that would help me determine the amount of solar radiation hitting a certain latitude on a certain planet given the following inputs: the degrees of latitude of the ...
2
votes
1answer
67 views

How long is the moon full

Is the moon the most full only for one moment As stated here and here Or does if stay the same full for a longer period of time (maybe because, the sun is grater then it, and light spreads out) ...
2
votes
1answer
69 views

How many observations does it take to determine the orbit of a TNO

Several observations of a distant solar object must be taken before determining its orbit, but in the case of objects discovered beyond Neptune's orbit, just how many are required over what period of ...
3
votes
1answer
38 views

Could spy satellites use laser guide stars (for adaptive optics)?

Are sodium lasers useful for Earth observing space telescopes/spy satellites?
5
votes
2answers
203 views

Does Pluto have impact craters?

I've heard from a lot of sources that Pluto doesn't seem to have any impact craters, but I see a few things that look like impact craters, highlighted in this picture: For comparison, here's ...
0
votes
2answers
80 views

Can a astronomical telescope view objects on Earth

I am new to telescopes, and planning to buy an astronomical telescopes like "Celestron AstroMaster 114 EQ Reflector". Just curious to know that whether it can be used to view objects on earth ...
1
vote
0answers
67 views

What is space temperature around Earth?

What is the equilibrium temperature that a black body will reach at the Earth's distance from Sun?
2
votes
1answer
56 views

How do I remove fungus from a telescope mirror?

I use a Celestron NexStar 130SLT Azimuthal Newtonian Reflector. I noticed that recently, due to the wet season, some tiny spots of what appears to be fungus have appeared. Having taking appropriate ...
1
vote
1answer
349 views

How many galaxies are there in the Hercules–Corona Borealis Great Wall?

The Hercules–Corona Borealis Great Wall is "to date (February 16, 2015), it is the largest and the most massive structure known in the observable universe" (source). How many galaxies is the ...
1
vote
1answer
125 views

What uncertainty does an error bar signify in astronomy?

When an astronomer talks about her/his topic and shows an X/Y-plot with error bars. What should one assume that those error bars represent? 1 standard deviation? Or 2? Or some specific significance ...
1
vote
1answer
111 views

Eternally collapsing objects?

As has been pointed out by some scientists, that black holes aren't stable bodies but are eternally collapsing objects. How does one come to such a conclusion? Is hawking radiation related to this in ...
2
votes
1answer
49 views

Available energy for potential life on Titan

There is an interesting discussion about whether there could be life on Saturn's moon Titan. (For example here.) The life could use reaction of hydrogen and acetylene which are being produced by ...
1
vote
0answers
32 views

Does the shape of a supernova remnant depend on the progenitor star's magnetic field?

The magnetic field activity in a star can be very chaotic and my question is are they somehow related?
0
votes
0answers
31 views

Review Content for my Comet Infographic

I've been hard at work in recent months on an infographic that details the anatomy of a comet... I'm a graphic designer and this is a fun little side-project of mine. It's only quite basic in terms of ...
1
vote
1answer
49 views

Which structure is represented in this video (if any)?

I know this is not supposed to be precise since it is just a movie but I would suppose it is based on real things. In the Contact movie intro https://youtu.be/EWwhQB3TKXA?t=1m I think the Milk Way is ...
1
vote
0answers
11 views

What is the difference between Space Dynamics & Astrodynamics in the engineering perspective? [migrated]

Within the context of Aeronautics, there are seemingly different meanings corresponding to Space Dynamics and Astrodynamics... ...
0
votes
1answer
46 views

How can I find out which known stars lie within or close to M8

I'm looking for a way to find stars within a certain region of space, the Lagoona Nebula in this case, based on what we currently know. Are there some databases that allow you to make such queries? ...
5
votes
2answers
165 views

Does the mass of the observable universe ever change?

First do we have anyway to even estimate the mass of the entire observable universe? And then is there any data that shows mass being gained or lost? Would we ever know if someone was playing with ...
0
votes
0answers
16 views

How easy is it to mine water on Ceres?

It has been suggested by some futuristic or sci fi leaning thinkers, that Ceres' surface might be mined for water to support human exploration and settlement of space. But NASA's Dawn mission and ...
3
votes
0answers
22 views

How thick can planetary rings be?

This arose from a comment on Worldbuilding. We have data from four planets in the Solar System with rings, which doesn't make for a very good sample size. Observations of exoplanets could change ...
4
votes
1answer
108 views

Is it possible to create a traditional clock solar system?

Is it possible to create the following system of satellites?: Place a satellite that orbits the some object X, once per day. Call it D. Place a satellite that orbits D, once per hour. Call it H ...
2
votes
1answer
44 views

Orbiting and landing on non-sperical objects

If we orbit a non-spherical asteroid or moon at a sufficient distance I believe that we can consider it to be a point mass. Therefore we can take up a conventional orbit. Assuming our lander craft is ...
11
votes
4answers
181 views

Where might a semi proficient amateur analyst participate in meaningful astronomical efforts

I am a retired engineer that has an ongoing interest in space efforts. In my youth I did work on the Apollo program but on propulsion and vehicle thermal control: not flight dynamics. I have ...
2
votes
2answers
58 views

How common are exoplanets in distant orbits?

Are there many single transits in the Kepler data, which might be exoplanets with a longer orbital period than the time they have been observed for transits? Can any conclusions be drawn about how ...
1
vote
1answer
64 views

What is the projection of Earth's axis on the sphere with the Sun in center (see explanation)

Seems like it is the most convenient SE community for this question.. Imagine the sphere, witch center is the Sun and radius is, say, ~1.5 distance from Sun to earth (in arbitrary time, precise ...
1
vote
1answer
67 views

How to run MOOG on OS X Yosemite

By what process can a user running the latest version of OS X Yosemite execute MOOG with $MOOG in bash? Due to the removal of 32bit libraries in OS X 10.7+, the ...
1
vote
0answers
24 views

Could evaporating hot Jupiters have metallic hydrogen on their surfaces?

Jupiter is believed to have metallic hydrogen in its core. And gas giants that migrate to become hot Jupiters are believed to evaporate, have their atmospheres blown away by their nearby star. Can ...
12
votes
2answers
2k views

Why do the planets in our solar system orbit in the same plane?

(Yes I'm excluding Pluto from this the same way it was excluded for not being a planet) Observing the planets orbit of the Sun they all seem relatively planar and roughly all orbit along the same ...
9
votes
1answer
581 views

Is there a limit to how hot a star can be?

I think that size and mass do not correlate to temperature, but then again these factors contribute to the internal pressure. I would like to know if there is a limit to how hot a star can get and ...
3
votes
1answer
30 views

Do celestial bodies have many asteroids orbiting them?

Are there statistics on the expected number of asteroids (of various sizes) to orbit planets and moons in our (or other) solar systems? Do we know of other natural bodies orbiting the Earth (besides ...
1
vote
3answers
58 views

What is the average color of the universe?

Our Earth, being a beautiful blue orb, has an overall perceived wavelength of somewhere near 470 nm, that being the wavelength of light blue, because the oceans play an enormous role in the weighted ...
1
vote
1answer
48 views

How large must an object be to be seen through a telescope?

I've studied this in a few optics classes before, but I'm drawing a blank at the moment. If I know the aperture size and focal length of a telescope, as well as how far away the object I want to view ...
0
votes
0answers
24 views

What is the probability of an astronomical body hitting you?

It appears that there is already a calculated ballpark for meteor fatalities, but what about other factors such as space trash, comets, and other miscellaneous items in space? Is it possible to ...
9
votes
1answer
589 views

Do all orbiting bodies eventually collide?

If two celestial bodies are in orbit, will they always eventually collide if not acted upon by outside forces?
2
votes
1answer
160 views

How to calculate conjunctions of 2 planets

So, the recent conjunction of Jupiter and Venus seems to have spawned lots of excitement over this "rare" event. But what I can't figure out, is exactly how rare it is. And I've seen such conflicting ...
3
votes
0answers
158 views

Why are there no stars on New Horizons images of Pluto

I followed the New Horizons Mission a little, and saw among others this image of Pluto: I wonder, why you can't see any stars on it. As far as my very basic knowledge in astronomy goes, I think you ...
3
votes
3answers
77 views

How much more massive would Pluto have to be to clear its neighborhood?

How much more massive would Pluto have to be to clear its neighborhood?
0
votes
0answers
20 views

Before Voyager 2, what were the highest quality photos of Uranus and Neptune?

I'm in search of historical knowledge of the outer ice giants, which seems so hard to come by. Right now I would be happy with just a photo of each, the best photo we had of them before Voyager 2. ...
1
vote
1answer
82 views

How do the orbits of Nu Scorpii and AR Cassiopeiae work?

I apologize for the way this question is worded but I don't think I know the proper verbiage. Basically, I want to know how the stars orbit one another in the two septuple star systems. For example, ...
0
votes
1answer
60 views

Where can I find a catalog for stars within 450 light-years of Earth?

Where can I find a catalog for stars within 450 light-years of Earth? I'd prefer one that has approximated masses as well.
0
votes
1answer
26 views

Hubble law, cosmological redshift and distance

I have got confused with some cosmology formulas which calculate distance. The most famous formula is indeed the Hubble law which says (nowadays) velocity is proportional to Hubble's parameter at ...
7
votes
1answer
148 views

How did New Horizons take such well-lit pictures of Pluto?

The photos of Pluto from New Horizons are truly beautiful. But considering that Pluto is so far away from its nearest start - our Sun - how is it so well lit up? Did the New Horizons have a massive ...
2
votes
1answer
306 views

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 ...
6
votes
3answers
206 views

Is it possible neutron stars are actual elements?

As you go up the periodic table (more protons), the ratio of neutrons to protons steadily increases as well. Are we sure there are absolutely no protons and electrons in a neutron star, or could there ...

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