Skip to main content
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 ...
HDE 226868's user avatar
  • 101k
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 ...
HDE 226868's user avatar
  • 101k
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, ...
abestrange's user avatar
  • 5,974
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,...
Gryphon's user avatar
  • 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 ...
Nuclear Hoagie's user avatar
70 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 ...
parasoup's user avatar
  • 5,051
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 ...
Tim B's user avatar
  • 77.1k
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 ...
Andrew Brēza's user avatar
66 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 ...
Starfish Prime's user avatar
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 ...
kingledion's user avatar
  • 85.4k
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 ...
Sandy's user avatar
  • 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 ...
The Square-Cube Law's user avatar
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 ...
HDE 226868's user avatar
  • 101k
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 ...
HDE 226868's user avatar
  • 101k
45 votes

How can the stars be wrong, so that an observer realises they're not in our world anymore?

There are patterns in the star positions that are very obvious, and which the observer would inescapably have heard of had they been visible from Earth. For example: A large area of the sky, in a ...
John Dallman's user avatar
  • 24.5k
44 votes
Accepted

How can the stars be wrong, so that an observer realises they're not in our world anymore?

The color of the stars. Other answer(s) explain a situation where the observer is in our Universe, but not in the Earth. You ask for stars which are wrong and it is clearly visible that it cannot be ...
Gray Sheep's user avatar
  • 3,739
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 ...
Mindwin Remember Monica's user avatar
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 ...
The Square-Cube Law's user avatar
40 votes

How can the stars be wrong, so that an observer realises they're not in our world anymore?

The stars are slowly moving relative to each other That movement is slow enough that you would not notice it with a single glance at the sky. But over a few minutes, constellations shift and warp ...
Surpriser's user avatar
  • 2,239
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 ...
Separatrix's user avatar
  • 118k
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 ...
Skek Tek's user avatar
  • 911
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 ...
LSerni's user avatar
  • 55.4k
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 ...
LSerni's user avatar
  • 55.4k
36 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,...
AlexP's user avatar
  • 90.6k
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 ...
Joe Bloggs's user avatar
  • 66.4k
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 ...
Corwin62's user avatar
  • 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 ...
Rubio's user avatar
  • 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 ...
Zxyrra's user avatar
  • 20.6k
31 votes
Accepted

The rotation of the sun's core doubles in speed every 10 years. How many years before the situation turns apocalyptical?

We have a problem here: we don't understand the solar core rotation really well. As you said, relatively recently (around 2017) it was discovered that the core rotates at about four times the speed ...
The Square-Cube Law's user avatar
31 votes

How can the stars be wrong, so that an observer realises they're not in our world anymore?

The stars don't move As the earth rotates throughout the night, the stars appear to move from one horizon to another. It almost seems like a celestial sphere is turning above the earth. But in this ...
Mutoh's user avatar
  • 449

Only top scored, non community-wiki answers of a minimum length are eligible