Astronomy Stack Exchange
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Where did Mars' water go?

Many sources indicate that there is ice water on Mars today, but it is mainly traces, here and there, but not that much. However, solid hypothesis state that there were oceans on Mars, see Wikipedia's Mars ocean hypothesis or at least large aquifers…
Thibault
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Is the rotation of the Sun and the rotation/orbit of the Moon around the Earth a coincidence?

While looking at sunspot information in connection with Amateur Radio, I found that the Sun rotates on a period from 27 days to 31 days. Its rotation is differential, at the equator it spins at a rate of about 27 days, while at the poles it's…
Adam Davis
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How much overlap will the Andromeda galaxy and the Milky Way have when they collide?

Measurements of Andromeda's blue shift let us conclude that the distance between the Andromeda galaxy and the Milky Way is decreasing and in a few billion years they will "collide". The blue shift only yields the radial component of Andromeda's…
Jens
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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 reviewed/studied some astrodynamics (Vallado, Bates, etc)…
tckosvic
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Is it possible that some stars are already black holes yet we see light emitted from before becoming a black hole?

For stars we see that are burning fuel at a fast rate, that are very bright, (or any star for that matter sufficiently far away from us) could it be that they are already black holes (the sufficiently large ones) and we are just seeing the light…
gigatexal
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How can I calculate moon phase and height?

How could I know what phase the moon is in when it's high in the sky during sunrise? How could I tell in general what its height in the sky will be at any given time?
JekylHyde
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Stars at near break-up rotation rates

Accretion discs are ubiquitous in astrophisics. As a direct corollary, they are important for the following question. Consider the following model, representing one of the most simple models for accretion discs. A central object is a star (pre-MS,…
Alexey Bobrick
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What happens to a star after it has become a red giant?

When our sun reaches the end of its lifetime , it will turn into a red giant. How long will it be a red giant, and what happens after a star has been a red giant? Does it turn into a planet after a long enough time spent, when it has used up all its…
bogen
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Why is carbon so rare on the Moon and on Mars?

Carbon is the fourth most common element in the universe and in the Solar system. It is about the ninth most common element in Earth's crust. It doesn't seem to be part of any of the ten most common compounds in the Earth's crust. So where is all…
LocalFluff
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Exercise: 2D orbital mechanics simulation (python)

Just a little disclaimer beforehand: I have never studied astronomy or any exact sciences for that matter (not even IT), so I am trying to fill this gap by self-education. Astronomy is one of the areas that has captured my attention and my idea of…
statespace
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How can I safely observe a Solar Flare?

Solar Flares obviously release extreme amounts of energy and extend thousands of miles out into space. Because they are so big I would like to be able to observe some of these events through a telescope but I am wary of damaging both my eyes or the…
user96
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How to detect emission lines in optical spectra?

Is there any handy module to detect emission lines in a spectrum like one we get from the Sloan Digital Sky Survey (SDSS)? You can see there are many emission lines like Ha,OI in the spectrum below. In fact the spectrum is a two column data set,…
questionhang
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If nothing travels at the speed of light, except light, how can a black hole also pull light into itself?

Is it because it has super massive gravity and energy? Or is it some sort of an anti-light component in it because it used to be a star?
Timtech
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How Does a Refractor Telescope Work?

As I understand it, the difference between a reflector and a refractor is that a reflector uses mirrors on the back to reflect the light to the secondary mirror then the secondary mirror reflects the light to your eye focusing the image with each…
Sarah Szabo
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Would an exoplanet without axial tilt have no seasons?

Would an Earth analog exoplanet which rotates around a solar analog, but without axial tilt, have no seasons? Would it be similar to how Los Angeles does not have very noticeable seasons compared to other parts of the Earth?
seijitsu
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