Today we know of over 4000 exoplanets, or extrasolar planets: worlds orbiting around stars not our sun. But in 1992, possibly the first exoplanet ever discovered came in the form that scientists did not expect. It was a pulsar planet, or a zombie planet, formed from the matter and debris in the aftermath of an exploding star.
In the 70s and 80s there had been exoplanets theorized and mathematically calculated by the strange behavior of stars. But it wasn’t until 1992 that a breakthrough in exoplanet hunting proved solid evidence that extrasolar planets are actually out there.
First of all, you need to know that there are many types of stars. They’re all not like our sun. One type of star is known as a neutron star. They’re the second densest type of object in the universe outside of black holes. They form when a giant star dies and explodes outward into space after its core has collapsed. Basically, the star becomes too massive to go on and explodes its energy outwards. The core of the star collapses and the star will either become a black hole or a neutron star.
Some neutron stars are called “pulsars” because they pulse off radio frequencies at regular intervals. The pulses are like clockwork, like a rhythm. And if the rhythm gets off, scientists know that something is up.
In one such case, astronomers Aleksander Wolszczan and Dale Frail tuned into the pulsar PSR B1257+12, 2300 light-years away. It was acting strange. It should have been pulsing at regular intervals but every now and then the pulses would be off. The off-beats came at regular intervals as well. After intensive study, Wolszczan and Frail came up with an explanation for why that was: it had two planets around it. One was three and the other four times the mass of Earth, and they rotated around about every 67 and 98 days.
So, they had discovered two planets orbiting around a neutron star…an exploded star.
When a star explodes, usually the planets in that system are destroyed or hurled out by the massive shockwave. However, after the destruction settles down, the gas and dust can then recondense. This, in effect, means that the planets in B1257 may be made out of parts of the planets that came before them. It goes without saying that no one believes that life could exist on these planets.
This was the first confirmed set of exoplanets. However, they weren’t planets around a main sequence star–a star like our sun. That wouldn’t be until 1995.
Visit the link below to interact with a visual timeline of exoplanet hunting: