Home > Physics, Science Journalism > Who discovered the planet going in reverse?

Who discovered the planet going in reverse?

All planets rotate on their axes while orbiting their Sun. Ours does too. But the axis on which our Earth rotates is tilted an angle of about 23.4 degrees, as can be seen by the way globes are mounted. And it is this tilt that causes the seasons. This tilt also leads to scenarios where near the Northern and Southern poles, we can experience 24 hour days and 24 hour nights (visiting one of these places at such a time, is on my things-to-do-before-I-die list).

But interestingly, the planet Uranus is tilted at angle of 97.7 degrees. If we imagine the usual plane of rotation of planets around our Sun as a table top, then the Earth will be seen as a spinning top whose axis of rotation is slightly tilted. In comparison, Uranus must be seen as lying flat on the ground rotating on its side. That is, the axis of rotation of Uranus is roughly along the plane of its rotation around the Sun. To see why that is interesting, imagine how day and night will be on that planet. When the axis of rotation of the planet is directed towards the Sun, then one half of the planet will get continuous day light. The other half is completely in the dark (this is just an extreme case of our planet having continuous days and nights near the poles during 2 seasons). During the two other seasons, its day-night pattern is similar to that of a normal planet. Uranus is, in that sense, unique.

But a newly(?) discovered planet that I read about in Times of India, a few days back, is unique in a different way. Normally a planet goes around the star in the same direction as the direction in which the star spins. That is all the planets travel in the same direction around the Sun. This is because, during the formation of the planetary system, all planets arise out of the same cluster of particles. These particles aggregate to form planets. Hence they all rotate in the same direction. But the new planet discovered rotates in a direction opposite to that of the direction of the spinning of the Sun.

This planet was discovered using the same technique as we discussed last time. The cause for this reverse motion is not very clear and still remains an open question. But the article itself is somewhat odd. The article refers to an astronomer, Daniel Bayliss, from Australian National University. When I googled for his name so that I could read more about this news item, I saw that all the news items refer only to Indian newspapers like this, this, and this.

Confused as to why I did not find any international news items, I searched with the planet name which was WASP-17B (BTW, WASP stands for Wide Area Search for Planets. The star around which it rotates is called WASP-17, which is about 1000 light years away from us.) and I saw many news items, but they were are dated in the month of August 2009. These were from the big news sites like National Geographic, BBC and New Scientist. And they all credit the discovery to scientists in the UK. The planet has a Wikipedia entry too.

It is curious that a planet that was discovered a couple of years back is being touted as a discovery again (at least that is what it appears to be unless I am missing something). When I went to the website of the Australian National University, I saw this press release about the planet. It is from this press release that a news agency prepared the news item which was used by the newspapers. But the press release also had contact details of the astronomer. So I emailed him a couple of days back asking for a clarification. I have not received a reply so far.


UPDATE (Jun 19th 2011): The scientist replied to my email a few days back, saying that the initial article was based on a paper which was only speculative of the reverse orbit of the planet and that his work covered a full transit and confirmed that the planet was indeed going in reverse. But the news reports were definitely messed up. The Times of India Report says, “now astronomers have stumbled onto one that goes the wrong way”, which clearly suggests that the planet itself was a new discovery.

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