This map shows the position of almost every radio pulsar known to modern researchers. The map is an equirectangular projection of the night sky in galactic coordinates, showing the entire sky as visible from Earth with our Milky Way galaxy running through the middle. The size of each circle illustrates the relative brightness (as seen from Earth) for each pulsar, and each circle emits pulses at the true frequency of the pulsar. The slider on top of the page lets you move through space, exploring different distances from Earth. Look to the counter in the top right to see what distance range is currently shown. Click on any pulsar to learn more about that object.
A pulsar is a specific type of highly-magnetized neutron star, created when a massive star undergoes a core-collapse supernova. Pulsars are very small (for a star) and rotate very quickly, emitting strong and narrow beams of radiation from their magnetic poles. If we (on Earth) happen to fall within the path of this beam as it sweeps around the sky the pulsar acts like a lighthouse with its beam periodically passing over us. Just like a lighthouse, the observable result for us on Earth is that the object gets very bright for a short amount of time and quickly fades away, over and over and over again, creating the strong pulses for which pulsars are named. This map includes pulsars discovered by radio telescopes.
Researchers have been looking for and studying pulsars since 1967, when pulsar B1919+21 was first discovered. At first, this object was an enigma; because its pulses were so consistent, some researchers (semi-jokingly) wondered whether we had found a beacon from some alien race. Now we know that pulsars occur naturally, though they may yet help us communicate with aliens: NASA included a map of our location in the galaxy using pulsars as landmarks on the Pioneer and Voyager Satellites, which are right now on their way out of our solar system. There are other (more practical) reasons to study pulsars too: they have helped astronomers test the theory of General Relativity, learn about the very thin gasses in between the stars, and much more. Almost all of the pulsars we know about are in our own Milky Way galaxy; though researchers are sure they are out there, pulsars in other galaxies are usually too far away and too faint for our telescopes to identify. The only exceptions are the few bright pulsars we find in the Milky Way's two best-known satellite galaxies, the Magellanic Clouds. These satellite galaxies are very close to the Milky Way which allows researchers to identify the pulsars they harbor.
There are several interesting trends you can spot in the animation above. For example, Our Milky Way galaxy is shaped like a very large and thick disk, and we (on Earth) are out towards the radial edge of that disk but close to the middle plane of it. That means that the pulsars (and other stars) relatively nearby are visible in all directions, but if you look only at objects that are further away, they are almost all in the plane of the galaxy. Here are some other trends to look for:
This website was built by Isaac Shivvers, while getting his Ph. D in astrophysics at UC Berkeley. Feel free to contact me with any questions or comments at moc.liamg@srevvihsi.
The pulsar data behind this site was assembled from the Australia Telescope National Facility's pulsar database.
The background image of the night sky is courtesy of ESO/S.Brunier, and was produced as part of the European Southern Observatory's GigaGalaxy Zoom project.
© Isaac Shivvers, 2013
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