109
votes
Accepted
What could make a star green?
Give it a circumstellar cloud of oxygen.
Some planetary nebulae, such as NGC 6826, appear green because of ionized oxygen.
Image in the public domain. Yes, this is a true-color image.
I see no reason ...
- 99.6k
99
votes
Accepted
Is using the Sun as a sort of 'garbage dump' safe?
If you could get the materials safely away from Earth and actually dump them in the Sun, no, there would be no danger.
The Sun is approximately 330,000 times the mass of Earth. To substantially change ...
- 99.6k
86
votes
If every star in the universe except the Sun were destroyed, would we die?
No. Life on Earth and our solar system in general would not be harmed by this sudden universal destruction.
Everything outside of the Solar system affects us via electromagnetic radiation, gravity, ...
- 5,578
78
votes
Accepted
What elements would be created in a star composed entirely of gold?
Unfortunately, no matter how much pure gold you add to your mass, you will never end up with a star. The reason for this is that fusing gold is an endothermic process, meaning that it requires energy,...
- 10.9k
72
votes
If every star in the universe except the Sun were destroyed, would we die?
We wouldn't even notice for several years.
The closest star to us (aside from the Sun) is Alpha Centauri, which is just over 4 light-years away. That means that whenever we look at Alpha Centauri ...
- 13.7k
71
votes
Accepted
How do seasons work in a binary system (planet orbits one star, not both)?
Update
I've updated my CDF to handle eccentric orbits and customization of star brightness, and (more importantly) to show long-term seasonal effects. A few notes:
Mousing over any of the ...
- 11.9k
71
votes
Would extracting hydrogen from the sun lessen its lifespan?
Assuming you're taking hydrogen from the surface, you'll be lengthening its lifespan.
The sun's outer convective envelope, within which hydrogen is cycled from the surface to its interior, doesn't ...
- 3,368
68
votes
Accepted
Is it possible for one star to orbit another?
I think you're missing some knowledge here, since what you are asking about is called a binary star system and they are extremely common.
Your planet can orbit the pair around their common center of ...
- 76.9k
68
votes
Is using the Sun as a sort of 'garbage dump' safe?
Dumping radioactive waste into space was actually considered in the real world
The idea of launching hazardous waste into the sun is completely absurd on so many levels. Or is it? Let's look at the ...
- 10.5k
65
votes
Killing a star safely
Problem: even if you could just stick a blanket over the sun, it is probably already too late. The solar system formed more than 4 billion years ago, and for all that time anyone who was watching and ...
- 69.6k
63
votes
Is there a way to create a bomb to destroy a star?
WARNING: While this post does point to a scientific paper there are a lot of doubts about the quality of that paper and how reliable it may be. The review process of the paper, credentials of the ...
- 97.5k
61
votes
How would people living in eternal day learn that stars exist?
People are curious
Humans, at least, are very curious. Shamans on spirit journeys, young men on adventures, and outcast groups in exile might all end up traveling into the night zone for one reason ...
- 85.1k
60
votes
Accepted
What would the signs of the Sun undergoing a supernova be?
First, if the Sun went supernova scientists would be terribly, terribly confused.
In order for a star to go supernova, it has to have a mass greater than at least 8 solar masses. Although there is ...
- 1,146
56
votes
How do you non-catastrophically reduce the mass of the Sun by half?
C. Must not create any phenomena that would have devastating consequences on life on the planets (i.e.: no radiation, excessive heat, energy surges) except for the diminishing of the Sun's current ...
- 134k
56
votes
What elements would be created in a star composed entirely of gold?
This star would not fuse gold.
Fusion reactions producing elements beyond zinc-60 are not energetically favorable; they are endothermic, and so consume energy. Several elements heavier than iron are ...
- 99.6k
52
votes
Exactly how far apart are nearby stars from one another?
An exact answer
The position of a star in space can be specified by three coordinates: Its right ascension, $\alpha$, its declination, $\delta$, which are collectively referred to as equatorial ...
- 99.6k
43
votes
Can stars that are not powered by nuclear fusion exist?
As another answerer provided, Neutron stars already do this.
So, I'm going to alter my answer somewhat to address whether there are other means by which a star-like object may exist, besides the one ...
- 10.9k
43
votes
If every star in the universe except the Sun were destroyed, would we die?
Frame challenge: It was not them who disappeared, it was us.
What is more plausible (but still a twist in the laws of physics), that an entire universe vanished or that a single solar system in the ...
- 14.3k
40
votes
Accepted
How to make an Earth with 27 suns work
How would this be possible?
It would not, for a range of reasons.
For the stars to coexist in such a system, they would have to be arranged in a way similar to planets in our own solar system. They ...
- 134k
39
votes
How would people living in eternal day learn that stars exist?
If they're avoiding both the heat of the day and the cold of the night then there are dawn and dusk people.
Most likely you have four main groups, two who move constantly and two who move and settle ...
- 116k
39
votes
How do you non-catastrophically reduce the mass of the Sun by half?
Wormhole
[A,C,D,E,F,G] A traversalable wormhole would be an excellent mechanism to remove mass from the sun. A wormhole is consistent with general relativity while avoiding all of the pitfalls of ...
- 901
39
votes
What would happen to a star if most of its energy were reflected back at it?
The star will very slowly reach a new equilibrium.
The energy being reflected back will lead to an increase in the star's temperature, starting with the photosphere (which is opaque). The photosphere ...
- 54.6k
38
votes
Accepted
How much damage would a cupful of neutron star matter do to the Earth?
This is more or less my best guess.
We're talking about a mass of about one hundred billion tons, composed of neutrons, previously held together by a terrifying gravitational field - and now ...
- 54.6k
37
votes
Is there a way to create a bomb to destroy a star?
You can always drop a chunk of degenerate white dwarf into it.
If the mass of the target star + your bomb is greater than the Chandrasekhar limit it makes a pop that would startle some people. You ...
- 3,719
36
votes
Accepted
Is there any conceivable way to "turn off" a star?
If you’re aiming to eke out the universe for as long as possible then ‘turning off’ your stars isn’t that good.
A better plan would be star lifting. This is, in effect, turning off the star by ...
- 66.2k
35
votes
What could make a star green?
Phil Plait of the Bad Astronomy fame:
Why are there no green stars: "The fault lies not in the stars (well, not entirely), but within ourselves".
Followup: Green objects in space: "So,...
- 85.2k
34
votes
Accepted
How would one go about making a star map for a planet that is within 50 ly of Earth?
I recommend Celestia (https://celestiaproject.net/). This is a very detailed (and free) astronomy simulator that lets you view planets, stars, constellations, etc. from any angle. You can view stars ...
- 476
33
votes
How would people living in eternal day learn that stars exist?
Total Eclipse
I know this isn't directly an answer to your question, but the novelette Nightfall by Isaac Asimov deals with a civilization living on a planet in a system with six suns which keep the ...
- 449
33
votes
What would the signs of the Sun undergoing a supernova be?
@SandyBeach is absolutely correct: The sun should not go supernova, and if it did so, we'd all be dead by the time we could tell.
However, assuming there's a handwaved mechanism to keep some sensors ...
- 20.5k
30
votes
Accepted
Is it safe to orbit HDE 226868?
X-ray radiation at the orbit of HDE226868
Cygnus X-1 is famous as one of the most powerful X-ray sources in the sky. According to the US Naval Observatory, the max flux of Cygnus X-1 (near the bottom ...
- 85.1k
Only top scored, non community-wiki answers of a minimum length are eligible