James K
  • Member for 7 years, 4 months
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Could Black holes forge heavier elements that have yet to be discovered?
22 votes

The heaviest elements known in nature are forged deep within stars. No, the heaviest elements are made on Earth in scientific laboratories, or in the extreme gravity of a neutron star's crust. ...

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Why Earth does not have rings?
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21 votes

A moon is held together by its own gravity, and pulled apart by the tidal action of a planet. If a moon comes too close to a planet it will be ripped apart by the planet's gravity and become a ring. ...

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Can the gravitational redshift of our sun be measured?
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21 votes

Yes. It can be measured in spectra of the moon. A paper The solar gravitational redshift from HARPS-LFC Moon spectra describes the measurment of red-shifts in Iron absorption lines in the spectrum of ...

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

Large masses can bend light, but space is largely empty. The light from distant stars and galaxies rarely passes close enough to another star or galaxy to have deviated. On the few occasions when it ...

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Are there any stars that orbit perpendicular to the Milky Way's galactic plane?
21 votes

Most stars in the galaxy are in the disc, but there is also a population in the galactic halo, these are in orbits at essentially random inclinations to the disc. There will be some that orbit ...

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Can the Earth be used as a gravitational lens?
21 votes

Yes, it's possible in theory, but beyond current technology to achieve. The focal point of the Earth is 15300 AU away. By contrast, Neptune is about 30AU. As a gravitational lens is not like a glass ...

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Is Earth unique in its fairly clear atmosphere?
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21 votes

Our atmosphere is only transparent to visible light, In most other wavelengths, some or all of the light is absorbed Image from Wikipedia, adapted from image by NASA Our eyes have evolved to take ...

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Is there any other theory to explain Betelgeuse's strange behavior except cosmic dust?
20 votes

Recently (for about a year) Betelgeuse has been very stable, without any significant dimming or brightening (See its light curve, type "Betelgeuse" into the search box). There has been no ...

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How much does the sky change in a few thousand years?
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20 votes

Here's part of the sky in the year 1 It is part of the sky you may know well, Orion and the dogs. I've marked the current positions of Sirius, Procyon and Betelgeuse, with green markers so you can ...

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In km/h, what actually is the "speed" of Andromeda away from us: cosmologically?
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20 votes

The rate of expansion, measured in the customary units of (km/s)/Megaparsec is not known with great accuracy. Recent measurements include 67.6 (SDSS-III), 73(HST) 67.8 (Plank) 69.3 (WMAP) [wikipedia] ...

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How can we know if a star which is visible in our night sky goes supernova?
19 votes

It is not possible to know. The speed of light is the speed of information. The information "the star has exploded" cannot travel faster than the speed of light, so there is no way to know ...

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How can dark matter be observed?
19 votes

The purple is a "weak lensing" map. To quote from the original authors: WEAK LENSING MASS RECONSTRUCTION OF THE INTERACTING CLUSTER 1E0657-558: DIRECT EVIDENCE FOR THE EXISTENCE OF DARK ...

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Could a planetary system have a planet in its center?
19 votes

The maximum mass of a planet is about 13 times the mass of Jupiter, above that limit they are considered to be "brown dwarfs" and have at least some deuterium fusion in their cores at some ...

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Why can I see sometimes a horizontal half moon instead of a vertical one?
19 votes

It occurs because the lit half of the moon points towards the sun, along a great circle in the sky. The half-moon will be 90 degrees away from the sun in the sky. So by (say) 8pm (at equinox for ...

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Would an analogue of the definition for planets also work for moons?
19 votes

In 2006 the IAU had a trilemma. They could decide that Eris was a planet, and potentially allow for future discoveries of tens of new planets. They could be inconsistent, declare that Pluto was a ...

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Star like light moving in the sky, what could it be?
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19 votes

There was a object, apparently flying above you, that you couldn't identify. By definition this is an unidentified flying object. However this does not imply that it was an extra-terrestrial ...

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Apparently two objects in Solar Eclipse image
18 votes

The people who say it is an internal reflection are right. This is an internal reflection inside the lens of the camera. There is no actual object there. In particular, Venus is not visible this ...

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Can you see the starting and the ending of a light beam passing in the distance?
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18 votes

Nothing forbids this, and it is actually observed astronomically. You need a very bright source of light: such as a supernova (which isn't a beam, but radiates in all directions) and very large ...

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Can you tell me which star this is?
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17 votes

"Nearly straight up" suggests Vega. At that time and location it is only 5 degrees from the Zenith. It is a notably bright star, much brighter than any which are nearby. Vega is a bright ...

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How did the authors of Surya Siddhanta find the diameters of other planets in the solar system?
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17 votes

The authors assume a geocentric universe (first thing that is wrong). They then assume that the planet Mars has the same apparent diameter as a globe 30 yojana in diameter (about 150 miles) in the ...

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"Periapsis" or "Periastron"?
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17 votes

No. These words are English, not Greek. "Periapsis" means the point on the orbit when the two bodies are at their closest. It doesn't matter if this good Greek or bad Greek, it is correct ...

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How early could we detect an asteroid the size of the one that caused the extinction of the dinosaurs?
17 votes

There are two classes of object. One is "asteroids" and the other is "comets". Asteroids orbit in fat ellipses, mostly between Mars and Jupiter, but some come closer and a few can ...

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Jupiter with a mobile phone and Celestron Astro FI 102mm Maksutov
17 votes

Congratulations on your purchase. The first pictures dont' show anything much. Just a out-of-focus blur. The last one shows Jupiter and three of its moons. I've overlaid the image onto a simulated ...

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Stargazing (Tenerife) - different quality today and yesterday
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17 votes

If you want to see the milky way, you really need the moon to have set. The moon sets about 50 minutes later each day, so you will need to go later. On the 28th of July, the moon sets at about 2 am ...

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Whereabouts of the Pleiades
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17 votes

With the exception of the Andromeda galaxy and the Magellanic clouds1, every star, star cluster and nebula that is visible to the naked eye is part of the Milky Way. The Pleiades is a star cluster in ...

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Fate of Jupiter when our sun dies
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17 votes

Jupiter won't evolve into a star, it is not big enough. A body would have to have about 80 times the mass of Jupiter for there to be significant fusion occurring in the core. The end of life of the ...

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If suddenly "knocked" or perturbed from its orbit, would gravity eventually return the Earth to its original orbit?
16 votes

In a 2 body scenario: Lets say there is one large body (sun) and a smaller body (asteroid) The orbit of the asteroid is an ellipse around the sun and completely stable. If you knock the asteroid it ...

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Have I nearly found the event horizon of a black hole?
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16 votes

This is the Newtonian model of gravity. It is a very good model, it is used for accurate calculating the motion of objects in the solar system to a very high degree of accuracy. However, for very ...

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Is it true that we see the center of the milky-way for only half of the year?
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16 votes

No, although there are times when it can't be seen, it isn't true that it is visible for 183 days of the year. The general question could be "If I take an arbitrary location on the sky (say a ...

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Space telescope located in outer solar system
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16 votes

The disadvantages would likely outweight the advantages. It's cold out there. This makes it easier to keep an infra-red telescope cool The sun's just a super-bright star. This means more of the sky ...

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