0
votes
0answers
3 views

Do all planets have a van Allen radiation belt?

Earth has the van Allen radiation belts. Which other planets have one? Can it be determined if distant planets in other solar systems have one?
0
votes
0answers
3 views

Why does the reduced equivalent width of a spectral line depend on surface gravity?

My question is why the reduced equivalent width of a spectral line depends on surface gravity. My professor wrote on the board that: $$\log(\frac{w}{\lambda}) = \log C + \log A + \log(g_n f) \lambda ...
1
vote
1answer
8 views

accuracy of an artificial satellite at certain magnitude

When we say that 'accuracy of a satellite is 10 $\mu$as at $V = 20$ magnitude'. What does this mean. Does it change over time.
0
votes
0answers
5 views

What is exactly the “longitude of the perigee”

Some moon phase calculation algorithms (apparently derived from Duffet-Smith's book, example here) seem to use a parameter called "longitude of perigee at epoch". What exactly is this? Can I assume ...
20
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?
0
votes
1answer
51 views

What makes the moon, a super moon

Caught a sight of moon tonight (by chance) and came in surprise that moon looks thrice in size to its usual size. Mostly called as Blue moon. Didn't succeed in getting the details and explanations ...
1
vote
1answer
14 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 ...
1
vote
0answers
6 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 ...
1
vote
1answer
33 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
68 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 ...
5
votes
2answers
94 views
+50

Is the diameter of the observable universe a relative quantity?

The diameter of my observable universe is 90 billion ly measured in proper distance. But isn't lenght a relative quantity in the theory of Relativity? Could an observer moving at a different velocity ...
3
votes
1answer
26 views

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

Are sodium lasers useful for Earth observing space telescopes/spy satellites?
4
votes
3answers
162 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
36 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 ...
-2
votes
1answer
30 views

Astrology question

Sometimes, for fun, I generate astrological charts for friends. I did a couple today, one for my newborn nephew (born today 8/2/2015 in Israel), and one for my 8 year old son (born 4/23/2007 in ...
0
votes
0answers
20 views

Why Earthian atmospehere is so thin?

Venus is somewhat lighter then Earth, yet has a much thicker atmosphere. One would imagine that the following should be true: During the formation phase, all inner planets had captured as much gas ...
1
vote
0answers
34 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
16 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
3answers
313 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
118 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
95 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 ...
3
votes
0answers
22 views

Has the conjunction between Venus, Jupiter, and Regulus only occurred twice in 2,000 years?

I recently heard the claim that mid-July, the "Star of Bethlehem" formed for the first time in 2,000 years, where the Star of Bethlehem is a three-way conjunction between Venus, Jupiter, and Regulus. ...
2
votes
1answer
42 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 ...
2
votes
4answers
83 views

Is expanding universe adding potential energy?

A system with two massive bodies has potential energy proportional to their separation. Since the universe is expanding, is the potential (and total?) energy of such a system slowly increasing? What ...
2
votes
4answers
124 views

Image sets for testing stacking algorithms?

I am looking for sets of astronomical images for testing different kinds of stacking algorithms. The idea is simple: if one has $N$ images of the same object, the signal-to-noise ratio of the ...
1
vote
0answers
24 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
20 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
37 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
10 views

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

Within the context of Aeronautics, there are seemingly different meanings corresponding to Space Dynamics and Astrodynamics... ...
0
votes
1answer
45 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
159 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
12 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 ...
1
vote
2answers
58 views

How/where to check where the Sun is (constellation)?

I would like to check in which constellation the Sun was in at some time in the past, any recommendations how to do that?
2
votes
0answers
18 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
92 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
40 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 ...
10
votes
4answers
177 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
56 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
63 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
55 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 ...
0
votes
1answer
8 views

How to specify SM libraries for MOOG

I am running MOOG on OS X Yosemite and with $MOOG running the abfind driver I can force fit elemental abundances with an appropriate input line list and model ...
1
vote
0answers
18 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 ...
-2
votes
0answers
17 views

Want to know the exact stream for cosmology

I want to persue higher study in cosmology.which iiser and which stream should I opt for??
0
votes
1answer
32 views

When will the next summer solstice and a full moon coincide? What day?

What day will the summer solstice and full moon coincide? As far as I know the next time will be in 2016. I would like to know what day.
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
567 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
27 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
46 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
44 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
17 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 ...

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