15 votes
Accepted

Are there other life giving sources of energy in space apart from stars (like nebulae, radiation, etc.)?

There are three important sources of energy in planetary bodies (or their moons) that may be important in determining their suitability for life. All of these are evident in various bodies in the ...
ProfRob's user avatar
  • 152k
5 votes

Are there other life giving sources of energy in space apart from stars (like nebulae, radiation, etc.)?

ProfRob makes a good point about tidal heating, but you can have internal heat sufficient for life even without this. The heat I'm referring to is heat trapped in a planet's core from its formation, ...
Drake P's user avatar
  • 213
5 votes

Are there other life giving sources of energy in space apart from stars (like nebulae, radiation, etc.)?

Stars function by nuclear fusion. There is energy that isn't released by nuclear fusion, nor from the nuclear decay of elements produced by fusion. There is the cosmic microwave background. This is ...
James K's user avatar
  • 121k
5 votes
Accepted

How bright would it be on the "face" of Titan

It's not hard to calculated brightness to distance, but that doesn't take into account cloud cover, which is important for Titan. Just looking at distance first, Titan (based on Saturn's distance) ...
userLTK's user avatar
  • 24k
5 votes
Accepted

Detection of the existence of any extraterrestrial life

I can't detect you simultaneously! I have no way of knowing if you are alive or dead, as you are not in the same room as me I can assume you must be at least 10 meters from me. That means you are ...
James K's user avatar
  • 121k
5 votes

Calculating "maximum" distance to an alien civilization

Suppose civilizations are randomly distributed in the galaxy (not necessarily evenly, but independent of each other). That means that there is a CDF $\Pr[d<x]=F(x)$, the probability for the ...
Anders Sandberg's user avatar
5 votes

How to know if an exoplanet is terrestrial?

One way of trying to do this is to plot a surface gravity versus mass plot. It's basically difficult for gas giant planets to hang onto a gaseous envelope without having a high surface gravity. This ...
ProfRob's user avatar
  • 152k
4 votes

How to listen to our world from 10,000 light years away?

For more fun, let's posit an experiment 10 000 years from now. I found some forum which provided this data for a transmitter: The Taldom transmitter is a large facility for longwave and shortwave ...
Carl Witthoft's user avatar
4 votes

How to listen to our world from 10,000 light years away?

As the above commentator says, our technology isn't sufficiently sensitive to pick up everyday radio broadcasts from so far away, and even if we could it wouldn't be worth sending them a message. The ...
Michael Walsby's user avatar
4 votes

How to prove to my friend that aliens have never visited earth

I don't think you can prove that aliens have never visited Earth. It's theoretically provable if one had a time machine, but without one, we can't really prove that aliens didn't visit Earth (say) 2 ...
Allure's user avatar
  • 4,544
4 votes

What does the amino acid found in the atmosphere of Venus mean?

An amino acid is any acid that has an amine in it. They are not necessarily found in proteins. They can be found in conditions similar to deep space, for example: In a laboratory at NASA Ames ...
Geeky Guy's user avatar
  • 143
3 votes

Are there other life giving sources of energy in space apart from stars (like nebulae, radiation, etc.)?

You can also have planets with powerful magnetic fields, a conductive body passing through them generates electric currents, that besides simply heating can also power chemical reactions directly (...
Nullius in Verba's user avatar
3 votes

How to communicate Fine Structure Constant to aliens?

Send two pulses of whatever (light, radio) you are using for communication, one a factor of $\alpha$ longer than the other.
Steve Linton's user avatar
  • 10.3k
3 votes

Would we detect a spacecraft before it landed on Earth?

So NASA recently re-detected the upper stage of a old centaur rocket from Surveyor 2 identified as NEO 2020 SOO. Now, there was some advantages with this object as people had noticed it before so ...
Rob's user avatar
  • 2,035
3 votes

Would we detect a spacecraft before it landed on Earth?

Some thoughts about Earth-based detection systems: We are looking at asteroids using radar: For instance the former Arecibo telescope could actively send out radio waves and calculate object position ...
B--rian's user avatar
  • 5,616
3 votes

How will the Breakthrough Initiatives affect other astronomy observations?

I was fortunate enough to spend the past week at a workshop held at the Green Bank Observatory (GBO), so I can give you a partial answer based on how the Breakthrough Initiatives affects it in ...
HDE 226868's user avatar
  • 36.6k
3 votes
Accepted

Kardashev scale

No extraterrestrial life has ever been found and we only know of one creature that has formed a civilisation: Homo sapiens. And we have not yet reached type I. So we know nothing from observations ...
James K's user avatar
  • 121k
3 votes
Accepted

What planets or exoplanets orbit the Sun’s elder twin HIP 102152?

No planets have been detected in orbit around HIP 102152. That does not mean that no planets exist, but that our current techniques are no able to detect them. Most planet are detected by the ...
James K's user avatar
  • 121k
3 votes

What programming languages does SETI (Search for ExtraTerrestrial Intelligences) most commonly use for signal processing?

A significant portion of SETI's work is done through a program known as SETI@home, which takes signals that have been received and processes them for responses, such as recurring patterns. Here is a ...
Timtech's user avatar
  • 1,685
2 votes
Accepted

How to prove to my friend that aliens have never visited earth

If your friend believes in these conspiracy theories he's not likely to listen to scientific reasoning, but I'll give it a shot. Obviously there's no direct evidence, but there are convincing reasons ...
Sir Cumference's user avatar
2 votes
Accepted

Is it only possible to look at solar systems with stars at least as old as ours to be able to find intelligent life?

Assuming the speed it takes to development intelligent life is the same in all solar systems, We don't know if this is true. We don't know if: Life has started on more than one planet in the ...
James K's user avatar
  • 121k
2 votes

How to listen to our world from 10,000 light years away?

The book of Yosif Shklovskii and Carls Sagan, "Inteligent life in the universe" gives a formula for how far a signal could travel and still be detectable by an antenna, which is influenced ...
Alexander Cska's user avatar
2 votes

Is there a way to know if there are/are not solar-system-like systems of objects without a star?

You're asking two related but distinct questions here: Well, what about nearly-massive-enough-to-be-stellar objects? Why would there not be more of these - and the inevitable satellites involved in ...
Eric Jensen's user avatar
  • 4,864
2 votes

Is there a way to know if there are/are not solar-system-like systems of objects without a star?

Brown dwarfs (ie sub-stellar objects that are too small to support hydrogen fusion) do exist and some brown dwarfs have been found to host planets. An example of this is the brown dwarf 2M1207. It ...
James K's user avatar
  • 121k
2 votes
Accepted

Would it have been possible to send a radio signal towards ʻOumuamua?

Answer posted under the wire during closure. Others may be able to write an additional and/or different answer as soon as two more reopen votes are cast. Would it have been possible to send a radio ...
uhoh's user avatar
  • 31.1k
2 votes

How to communicate Fine Structure Constant to aliens?

We've already attempted to communicate with aliens (and I don't mean teenagers), notably using Voyager 1 and 2 and their "gold records". Any intelligent technological civilization should ...
StephenG - Help Ukraine's user avatar
2 votes

Are there other life giving sources of energy in space apart from stars (like nebulae, radiation, etc.)?

The answer by mentioned two internal sources of energy in planets and moons, etc.: one) Tidal heating. In some situations tidal heating hasno significant effect, in ohters it can make a cold moon ...
M. A. Golding's user avatar
2 votes

Would we be able to discover a Voyager-style probe from a stellar civilization?

Small asteroids are occasionally, but routinely discovered, often just before or just after closest approach. For example a 3.5m asteroid 2021 RS2 was discovered at a MEO distance. It has a ...
James K's user avatar
  • 121k
1 vote

Has SETI searched the solar system for life?

If you mean SETI search by radio signals, afaik they would have already shown in our records if they came from within the solar system. If you mean generic search for life, yes, a lot of effort has ...
Helen's user avatar
  • 399

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