For those who aren’t as into astronomy and exotic stars as I am, a pulsar is the dying remnant of a star that blew off its outer shell. They are neutron stars and they spin at incredibly high rates of speed. Now, a neutron star is an object that, due to the explosion of outer shell, has been squeezed together into a highly dense object. So powerfully was this object squeezed by the explosion that the atoms have compacted so close together that the electrons contact the protons and neutralize each other, literally creating neutrons.
As the neutron star spins it emits bursts of energy across the electromagnetic spectrum. These bursts pulse from the star in a very regular pattern and it’s these pulses that earn it the name “pulsar.” So regular are these pulses that, when scientists first discovered one they named it LGM-1 for Little Green Men. (They didn’t actually believe that the pulses were a beacon for interstellar travelers, but the idea did come up more than once.)
We can hear pulsars. Here’s a video of a rather normal sounding pulsar:
Each sound you hear is a pulse.
But there’s an issue here that some of you might have picked up on. Space is airless, and sound requires air to travel, So how do hear anything across the vacuum of space?
Actually, you already know the answer if you think about it.
If someone shouts to you from across the street, you’ll hear them. But if they shout to you from the other side of town, you probably won’t. Sound waves are actually a lousy medium for the transmission of information. They just don’t work over long distances. Thankfully, there’s a solution in the form of radio waves, microwaves, and the like. Radio and microwaves are waves, just like sound. The big thing they have going for them is that they work over long distances.
When you talk to someone on your cellular or listen to your radio, you’re not listen to the radio waves. You’re listening to a computer’s interpretation of radio waves that it’s receiving from a distant source. It knows how to change those radio waves into sound waves and that’s what you hear. Pulsars, like I said, emit all kinds of waves and we can do the same thing with those waves that your cellular does.
In other words, the waves reach Earth, we pick them up, and our computers assign sounds to the waves.
Now, check this out. This is the sound of the Vela Pulsar, the brightest object in the sky… or it would be if you could see gamma rays. It’s also spinning at an exceptionally high rate of speed. While the pulsar in the video above spins around once per second, the pulsar in Vela makes one complete rotation in 89 milliseconds.
Note: Whoever uploaded this video to YouTube misnamed it. This is the Vela Pulsar. There is no pulsar in the Vega system.