# All Questions

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### 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 ...
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### What types of signals is SETI (and other such efforts) looking for?

This seemed to be the closest group for this question. Every few months there are a few articles asking "Are we alone in the universe" which focus on the Fermi Paradox, the Drake Equation, and end by ...
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### By what physical process does a telescope mirror reflect photons?

When incident light interacts with a telescope mirror, the light is reflected. Assuming that during the interaction, the light behaves as a particle, why does the photon bounce off of the electron ...
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### 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?
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### 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 ...
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### 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 ...
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### 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.
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### 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 ...
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### 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 ...
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### 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 ...
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### What is space temperature around Earth?

What is the equilibrium temperature that a black body will reach at the Earth's distance from Sun?
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### 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) ...
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### Astrology question [on hold]

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

Are sodium lasers useful for Earth observing space telescopes/spy satellites?
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### 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 ...
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### 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... ...
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### 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 ...
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### 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?
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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