When was the first exoplanet found

Hatzes, A. Butler, R. Howard, A. Batalha, N. USA , — Kreidberg, L. Snellen, I. Hoeijmakers, H. National Academies of Sciences, Engineering, and Medicine. Exoplanet Science Strategy National Academies, Google Scholar. Download references.

Article 27 OCT News 25 OCT Article 20 OCT Article 03 NOV News 09 NOV Research Highlight 05 NOV News 04 NOV Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily. Neutron stars are the second densest type of object in the universe outside black holes.

They form when a giant star dies and explodes outward as a result of the collapse of its core. Put simply, the star becomes too massive to go on and expels all its energy into the surrounding space. The core is a sort of ground zero of this detonation.

When that core collapses, depending on the size of the star, it becomes either a neutron star or a black hole. Think of many of them like a drummer — fast regular beats.

A breakthrough in provided rock-solid evidence of planets. It should have pulsed every 0. Yet those 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 every 67 and 98 days, rounded up.

Pulsar planets are somewhere in between a zombie and a chimera. When a star explodes, usually the planets in that system are destroyed or flung out by a shockwave. But after the violence settles down, the gas and dust can recondense.

This, in effect, means that the three planets in B may be made out of parts of the planets that came before them. Given the extreme radiation in these systems, almost no one has ever thought that the B system could host life. So, while the discovery was major news, it meant astronomers had the first verified planets around another star, but no proof of planets around a main sequence star like the Sun.

That kind of confirmation was still a few years away. From the s on, many groups had been on the hunt for the first planet around a Sun-like star. Some candidates came and went.

Others required dozens or hundreds of observations to officially confirm. But an observation in January proved to be the real deal. Didier Queloz, a grad student at the University of Geneva, was working with his advisor, Michel Mayor, on the search for extrasolar planets via radial velocity, in other words, wobbles. Reportedly, his find was a chance coincidence. Out of a catalog of radial velocity signatures, he chose an F-type star called 51 Pegasi, roughly 50 light-years distant.

He was trying to calibrate his planet finding code, opting for the star as one of a few promising candidates. It fell into place that night, a strong signal roughly every four days. Measurements placed its minimum mass near Jupiter — meaning the object was without a doubt a planet. There was some reason to be scared: finding a planet was then — and in some ways is still — really hard, and there were plenty of mistakes, ghosts, inexplicable data points, and other hiccups that never seemed to form a planet or a brown dwarf.

Much of the rest of was spent by Queloz convincing Mayor that he had truly found a signal, not an instrument error or other quirk of observing. In a paper, based on this concern, Walker backed away from the claim that the signal from Gamma Cephei represented a planet. But as it turns out, the star had been misclassified. Walker had been fooled into worrying he was fooling himself. His caution was natural, given the atmosphere of skepticism bordering on hostility.

Maybe it is best to say that Walker detected the planet but did not quite discover it. In , he and his collaborators reported an intriguing Doppler signal around a star called HD The signal was crystal clear. Its characteristics were compatible with orbital motion, and incompatible with rotation. This would seem to be a slam-dunk discovery. There were some weird things about the putative planet. First of all, the orbit is not close to being circular. Second, the planet is 11 times more massive than Jupiter, which seemed outlandish.

Finally, the orbit seemed way too small for a giant planet. According to the theory of planet formation, giant planets should never form so close to the star. Latham thought it could be a planet, but some of his team members and most other astronomers thought that was a stretch. Their paper only mentions the possibility of a planet by way of speculation. More likely, they wrote, it was a brown dwarf, a sort of failed star that never ignited nuclear fusion reactions. We know that a few percent of sunlike stars have a giant planet with a small, highly elliptical orbit.

And some of them do have masses as high as 10 or even 20 times that of Jupiter. Latham has a good claim to be the first to discover an exoplanet, but this is only from our retrospective view.

The claim was true, and amply justified by the data. But at the time, it was not believed, because of the prejudice that planets should look and act like the planets in the solar system.

What came next was a stunning surprise. In , Aleksander Wolszczan and Dale Frail announced the discovery of two planets, comparable in mass to the Earth, using a variation on the Doppler method. The evidence was watertight and convincing. Pulsars are among the most exotic things in the universe. They are remnants of supernova explosions, which take place when a massive star runs out of nuclear fuel and becomes unstable. A pulsar packs the mass of the entire sun into a ball only 20 kilometers across, making it so dense that with one false move it would collapse and become a black hole.

Also, it can spin around hundreds of times per second, and spew forth radio waves, x-rays and lethal doses of radiation. How should we score this candidate for the First Exoplanet?

The claim was true and justified. It was believed and is still believed by the astronomical community. The only hang-up was whether the objects orbiting the pulsar should qualify as planets. The pulsar discovery forced a more careful appraisal. Maybe the word planet should be reserved for objects orbiting a normal star, not a zombie star. Some astronomers insisted that planets must form within the swirling vortex of material surrounding a young star.

Maybe some of the exploding material ended up falling back down and started orbiting the neutron star, and the planets formed out of that material. But the pulsar planets were treated as freaks, and the search for more of them has turned out to be barren and unproductive. Only one other pulsar is known to have a planet, and even in that case, the evidence is not as secure. That brings us to Earlier, Mayor had helped Latham observe his star.

Then, he and his student, Queloz, decided to go planet hunting themselves. They had a near-monopoly on a telescope in France, which allowed them to monitor more stars than Walker or Latham.

One of their stars, a sunlike star named 51 Pegasi, was moving to-and-fro with an amplitude of 50 meters per second, and a period of only 4. The signal implied the existence of a planet with a minimum mass in between that of Saturn and Jupiter. That was a mass that made astronomers comfortable. Less comfortable was the orbital distance: only one twentieth of the distance from the Earth to the Sun.