Community Digest

Top new questions this week:

Is the measurement of distance and position of remote celestial bodies accurate?

Considering that light is affected by gravity, how accurate are measurements of distant stars and galaxies? When light passes through objects with great mass, such as Jupiter size planets, stars, or ...

gravity exoplanet space-telescope  
asked by Cris 14 votes
answered by James K 21 votes

Is it possible to observe strong gravitational lensing with amateur telescopes?

Strong gravitational lens systems like the Cosmic Horseshoe have been imaged by scientific space telescopes, but have any amateur astronomers accomplished this? Or are amateur/small ground based ...

telescope amateur-observing gravitational-lensing  
asked by 2080 8 votes
answered by James K 11 votes

The physical processes of emission lines in cosmic nebula

I think I understand how absorption lines in cosmic bodies occur. But after reading about the emission lines in quasars I am wondering more and more about the physical processes causing the emission ...

light nebula radiation  
asked by NeStack 7 votes
answered by Eric Jensen 8 votes

Nomenclature of Interstellar Objects and Stars

I posted this question on the space exploration SE but people recommended that it would be more on-topic here. Could someone please help by giving some definite laws of nomenclature for celestial ...

asteroids star-systems nomenclature  
asked by Raghavendra Singh 6 votes
answered by James K 6 votes

Is there a link between the amount of swirling and vorticity in a gas giant's atmosphere and its distance to its Sun?

This is an empirical observation of mine: I have noticed that out of the 4 gas giants in our Solar System, Jupiter's atmosphere has the most visible swirls and complex cloud patterns, followed by ...

planetary-atmosphere gas-giants  
asked by Hash 6 votes
answered by Connor Garcia 4 votes

Where can I find Arecibo's data archive?

Does anyone know where I can find Arecibo's historical data? After much searching, I can find neither hide nor hair of it. It doesn't help that the search results are completely dominated by the news ...

telescope raw-data  
asked by f_n_lyre 5 votes

What is the Inner Horizon of a rotating black hole?

My understanding is that any object with non-zero angular momentum which undergoes gravitational collapse to a black hole will become a rotating black hole. In reality all black holes will be rotating ...

black-hole inner-horizon  
asked by John Davies 4 votes
answered by tfb 5 votes

Greatest hits from previous weeks:

How does neutron star collapse into black hole?

We know the spectacular explosions of supernovae, that when heavy enough, form black holes. The explosive emission of both electromagnetic radiation and massive amounts of matter is clearly observable ...

black-hole neutron-star astrophysics  
asked by SF. 41 votes
answered by jmarina 23 votes

Does the sun's rising/setting angle change every few months?

When I lived in Darwin, Australia, I noticed that the Sun set in a slightly different direction to the West. In the evenings, I used to sit on a couch and watch TV. There was a huge window to my right ...

the-sun sunrise sunset  
asked by happybuddha 15 votes
answered by JohnHoltz 21 votes

Why does the Earth have a tilt of ~23°?

Is there a reason that the Earth has the tilt that it does (~23°)? How do we know which way is supposed to be 0°? Does this tilt have major consequences on the planet? Has it changed and will it ...

earth rotation  
asked by Jackson 26 votes
answered by e-sushi 25 votes

Will Earth lose the Moon before the Sun goes into supernova?

Ive read on some sites and saw on youtube videos that the moon is getting away from earth by 1-3 cm a year. Is this enough to make the Earth lose the Moon before the Sun goes into Supernova? Im ...

the-moon the-sun gravity earth supernova  
asked by hawaii 17 votes
answered by David Hammen 28 votes

Shouldn't this cause a fire?

This website shows a telescope projecting the sun onto a blackboard: Why isn't the board catching fire? You ...

telescope optics  
asked by Bookaholic 25 votes
answered by supercat 34 votes

Why do Black Holes in the middle of galaxies not suck up the whole galaxy?

As stated in several sources, it's supposed that in every galaxy there is a black hole in the middle. My question is, why do these black holes in the middle of galaxies not suck up all the ...

black-hole galaxy  
asked by OiRc 43 votes
answered by Phiteros 85 votes

Why doesn't the sun pull the moon away from earth?

If the suns gravitational pull is strong enough to hold much larger masses in place (all the planets) and at much greater distances (all planets further away from the sun then earth) why does it not ...

the-sun orbit the-moon gravity earth  
asked by TheDudeAbides 11 votes
answered by David Hammen 20 votes

Can you answer these questions?

How to derive density and mass from the pseudo isothermal model for mapping the density profile for dark matter?

I recently read about dark matter haloes and ways to profile their density. I came across this model called the pseudo isothermal model for the halo and I wanted to know how you would model the ...

dark-matter resource-request  
asked by Papernapkin23 2 votes

How would one estimate the rotation period of a star from its spectrum?

The figure is shown; the measurements were taken on two consecutive observing nights. The Ordinate is the flux normalized to continuum and the abscissa is the wavelength scale. You can see the "...

orbit rotation spectroscopy spectra stellar-astrophysics  
asked by Jay D 2 votes

How can you determine the date using nothing but a star chart from the day and the time?

I'm doing a science olympiad event called Reach for the Stars, and one question that I've encountered provides a star chart and time of day, and you must figure out what month of the year it is from. ...

star time positional-astronomy star-maps  
asked by Random_Guy6666 2 votes
answered by planetmaker 0 votes
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