B Feasibility of Sending a Radio Signal Detectable from a Neighboring Star

[Trysse]

TL;DR

Can we send a signal to nearby stars?

I have been wondering what it would take to send a radio signal that could be detected from a neighboring star system (for example, Alpha Centauri, ~4.3 light-years away).

1. Transmitter size: How large would a transmitting antenna or array need to be for such a signal to be detectable above background noise?
2. Energy requirements: How much transmission power would be required for detection using a large, modern radio telescope at the receiving end?
3. Feasibility: Could this power realistically be generated and sustained with current or near-future technology?

I am only thinking about conventional radio communication and would like to know if there are existing calculations or real-world examples (such as planetary radar or deep-space communication) that provide a useful comparison.

The reason for the question is actually the other way around; Can we reasonably expect to receive radio signals from intelligent life on other stars (if it exists at all)?

 

[FactChecker]

Is the broadcast and/or reception directional and targeted to/from the Earth?

 

[phyzguy]

Also, how large is the receiver?

 

[phinds]

What research have you done on this question? What have you found out so far? With 75 posts, you should know by now that this is not a Q&A forum. You need to show some work on your own.

 

[Baluncore]

The reason for the question is actually the other way around; Can we reasonably expect to receive radio signals from intelligent life on other stars (if it exists at all)?

Have you read the similar thread.

R

I Thread 'How big a lunar radio telescope to detect Earth-like signals?'

Jan 22, 2025

A problem with the SETI search is it looks for a specific radio frequency and even worse it has to be directly pointed at us to be detectable.

We can’t from Earth just try detecting normal radio signals like we put out with radio, television, cell phones, etc. because from other planets it would be completely drowned out by our own transmissions.

There is a plan now to put a radio telescope on the far side of the Moon to get a highly sensitive radio telescope not suffering from interference from Earth transmissions. How large would it need to be to detect the total radio signals...

• RobertGC
• Lunar Radio Telescope
• Replies: 19
• Forum: Astronomy and Astrophysics

 

[DaveE]

More than anything else, it depends on whether they are listening. We've been sending signals of some sort for almost a century. Have you heard about SETI? Go look up what they have to say about this.