A darling of NASA and of the general public, the Kepler Space Telescopes, dedicated to looking at extra-solar planets, may be soon ending its run. A recent hardware failure on the Kepler has led experts to give Kepler just one more year.
Kepler had four reaction wheels, which keep Kepler steady and able to focus unerringly at distant stars and planets. Kepler really needs three wheels to achieve this job, but has four just in case. Earlier, in July, 2012, one of these wheels had broken down, putting engineers slightly on the edge. Kepler, however, continued to function as well as it always did.
On 9th May, engineers found Kepler in automatic safe mode, since something was wrong. To their dismay, they found that one of the three remaining wheels had malfunctioned. Kepler’s days seemed numbered.
Kepler stares at faraway world, shielding its own cameras from the glare of the Sun. However, light from the Sun hits the craft (and, in fact, fuels it) and exerts pressure on it, called radiation pressure. No matter how small this is, this is enough to throw Kepler a bit off its line of sight. And this is where the wheels come in, ensuring that the photons are not the nuisance that they really are.
Engineers are scrambling for ideas to save Kepler. They are trying to use the boosters to compensate for the reaction wheels, but this won’t give the stability that Kepler enjoyed. Its planet watching days may be over.
Forget the world, the Sun is not enough. Astronomers have found a planet outside our own Solar System, which has as many as four suns! Yes, this planet, thought to be a gas giant, orbits four different suns.
The planet was discovered by volunteers who were using the Planethunters.org website, which allows enthusiastic astronomy amateurs access to a lot of data from NASA’s Kepler’s Space telescope. Kepler is built specifically for detecting exoplanets. The planet, named PH1, after the website, is just 5000 light years away, a stone’s throw away on the cosmological distance scales.
The planet is believed to be about the size of Neptune, just a bit larger. The interesting thing about this planet is the number of suns – there are four of them. Now, maintaining a stable orbit around four different suns is a very difficult and delicate problem. While it is moderately difficult to calculate the stable orbit configurations around one star, it is a huge pain to do it around two stars and impossible for four suns! There are virtually no stable points in the gravitational field in the region, where the planet can reside for an indefinite period of time.
We all know a single star – our Sun is an example. Now, imagine another star around it. This forms a binary system of stars. These are very abundant in the Universe – two stars circling around each other – and these reveal a lot of information about star formation and their subsequent evolution. Now, add two more stars orbiting this central binary system of stars! This is a highly improbable configuration. These outer stars will have a very hard time following a stable orbit around the core binary.
Now, throw in a gas giant planet in the mix! And what you get is utter confusion, if you could somehow see the pattern in the gravitational field. No one knows for how long this planet has existed or for how long it will exist.
One can only imagine the spectacular sunrise and sunset on the planet, but then all four suns won’t be rising or setting at the same time.
As if astrophysics didn’t have enough problems on its hands, it seems that a new discovery has handed over a new challenge. An exoplanet pair, discovered by the exoplanet hunting Kepler Space Telescope, unimaginatively named Kepler 36-b and Kepler 36-c according to accepted catalog practices, turns out to be spectacular blow for established planet-formation theories.
The two planets are very close to one another. They orbit their parent star, but they are separated by only 1.9 million kilometers. This turns out to be 0.01 AU, an AU being an ‘Astronomical Distance’, which is the average distance between the Earth and the Sun. So the two planets are a hundred times closer to each other than the Earth is to the Sun.
Astrophysicists wouldn’t be worried, yet. True this is very odd, but it doesn’t transgress the rule books. Here comes the blow: The two planets are as different as Venus and Neptune!
How is it a problem?
In our own Solar System, Venus is a rocky planet meaning that it has a solid rocky ground to stand on. It’s not a ball of compressed gas. In fact, Venus very much has a surface and it is riddled with numerous volcanic features, like volcanic domes, large fissures on the ground and rolling planes formed by large sheets of solidified lava flows. Kepler 36-b is not quite Venus in the volcanic sense, but is definitely rocky. It’s more like Earth, minus the oceans. Only that it is four times heavier than Earth, suggesting that is very dense.
Neptune is as unlike Venus as a planet can get. It is a gas giant and has no solid ground to stand on. It’s much larger than either Venus or Earth. Kepler 36-c resembles this gas giant.
Planet formation theories suggest that when the disc of rocks, gas and dust spinning around a parent star coalesces in clumps to form planets, the gas and dust are naturally flung far away from the center, while the rockier bits of the initial soup of raw materials stay within the vicinity of the parent star. They coalesce to form rocky planets. This explains the occurrence of rocky planets to the interior and the presence of the gas giants farther out for our own Solar System.
Since the forces involved in this process are those of gravitation (due to the star) and the centripetal forces (due to the rotation of the disc of raw materials), scientists would have expected the same rule to work for any planetary system, as these forces are both ubiquitous and inescapable.
But that can’t be the whole story!
That however is not the case apparently. The atmospheres are also very fascinating. Kepler 36-c has an atmosphere which is 10 times as dense as Kepler 36-b, even though they are at almost the same distance from their parent star.
Scientists like puzzles, especially those which can rewrite books. Nothing is ever sacred, not even the physics of the heavenly bodies.
No, we haven’t found life outside Earth as yet, but we have definitely improved our prospects. A growing number of telescopes has fuelled a burgeoning number of exoplanet discoveries, led primarily by the Kepler Space Telescope, which has detected 2330 long-period planets (planets having a period of more than a few days) till date. It has performed really well as compared to ground based telescopes, but there are plans to either upgrade it or replace it with a better model. According to Kepler, the count in the Milky Way now turns out to be 1.6 planets per star, and there being 100 billion stars, the count is 160 billion planets just within our galaxy!
Kepler Space Telescope
Kepler works using a very simple principle. It monitors the light coming from certain stars over a period of a number of months. The data is then sent to ground based command centers, which analyse the data and look for the presence of any periodic dimming and brightening events. Any such periodic changes in the brightness of a star suggests that there is another body circling it, which periodically eclipses the star just a bit during its transit. This method also helps the telescope pick up periodic wobbles of the parent star. Observing the wiggles this causes in the spectral lines of the star, scientists can infer not only the presence of an alien planet, but also pinpoint its mass and orbital period.
Very recent observations by Kepler show a marked rise in the number of Earth-like rocky planets being discovered. These might not be of the same size of the Earth, or they might not orbit their stars at the optimal ‘Goldilocks’ distance, but they are not gas giants. This is important, since gas giants are not presumed to hold liquid water or harbor any kind of life form.
The study leading to this estimate of the number of exoplanets was led by Arnaud Cassan from the Paris Institute of Astrophysics and their work appeared in the January 12th issue of Nature.
Contact may not have been such a far-fetched movie after all!
The 100-m Green Bank Telescope in Virginia has just picked up a strange radio signal, originating from KOI 817 (with KOI standing for Kepler Object of Interest) that looks as if an alien civilization is transmitting to us. SETI is excited as this is the type of radio signal it would expect from an alien civilization.
Not from an alien world
However, before the excitement can get too wild, SETI says that this signal is definitely terrestrial, rather than extraterrestrial. The signals have “terrestrial radio frequency interference” or RFI. Right now, the signals are a great source for SETI astronomers to study radio-frequencies, should they encounter a radio-emitting alien civilization.
The radio signals are narrow in frequency range (photo above), much narrower than anything that would be produced by an astrophysical radio source. The frequency of the signals is also perfect! Even the Doppler shift is just right, with the frequency decreasing at the precise rate expected from the relative motion of the transmitter and the receiver. A team from UC Berkeley has this to say:
These signals look similar to what we think might be produced from an extraterrestrial technology. They are narrow in frequency, much narrower than would be produced by any known astrophysical phenomena, and they drift in frequency with time, as we would expect because of the Doppler effect imposed by the relative motion of the transmitter and the receiving radio telescope
Kepler has been remarkably successful in detecting exoplanets. It has achieved much success by looking at ‘transits’, or the passage of planets in front of their suns. Kepler needs four transits to confirm the existence of an alien planet. This takes around 3.5 years.
So, tantalizing it might seem, but it’s just not true. Kepler has not yet found alien life, leave alone intelligent alien life. But the search continues…
Scientists report the finding of true two Earth-sized planets orbiting a star very similar to the sun, using the Kepler telescope. The discovery was announced today. Named Kepler 20e and Kepler 20f, these are the smallest planets ever to be discovered.
The location and details
The stellar system is located 950 light years away from Earth. Both planets are about the size of Earth, with one of them being slightly smaller. This is important, since we now know that we can indeed detect planets the size of Earth in another stellar system. In the future, we might indeed stumble upon a planet, the size of the Earth, with conditions similar to our home.
The planets orbit the star a bit too close for comfort and the surface temperature is too hot to sustain the kind of life we know. It’s not a true twin of the Earth, but this does indeed bring us tantalizingly close to finding one.
+2 for Kepler
This is again a feather in the burgeoning cap of NASA’s Kepler space telescope, which was recently lauded for finding a planet, called Kepler 22b, orbiting another star in the Goldilocks region.
Both Kepler 20e and 20f are rocky planets and have an estimated mass of 1.7 times and 3 times the mass of the Earth respectively. While Kepler 20e lies at a distance of 7.5 million km away from the sun, making it 20 times as close to the star as Earth (150 million km), Kepler 20f, does slightly better at 16.5 million km. Kepler 20e takes a mere 6.1 days to complete an orbit around the star, while Kepler 20f takes 19.6 days.
There is no possibility of liquid water, or even an atmosphere on either of the planets. However, astronomers are hoping that, given the plethora of exoplanets being discovered, one will turn out to be just right’ for life.
It’ a great planet to get a tan on, except for the minor detail that you may not make it back. A real-life Tatooine planet, orbiting two stars, has been discovered by the Kepler Space Telescope. This strange world is 200 light years away.
Tatooine is the name of the fictional planet of the Star Wars saga, where much of the story is based.
A Real-Life Tatooine
The discovery is stunning, since this is the first time such an object is being discovered. The planet is a giant one, slightly larger than Saturn, but made up of heavy elements. It orbits a binary star system. This marvellous system is named the Kepler-16 system, according to the Kepler Telescope’s cataloguing scheme.
This settles once and for all the question as to whether planets can really orbit binary star systems. The planet, Kepler 16b, is absolute proof that such a thing can happen.
The Star Wars team is thrilled. Visual effects supervisor at the Industrial Light and Magic firm, the company behind the Star Wars effects, John Knoll, says:
It’s possible that there’s a real Tatooine out there. Kepler 16b is unambiguous and dramatic proof that planets really do form around binaries.
How it was discovered
The planet was discovered by the so-called Transit Method. The exoplanet was discovered by noting the dimming of the stars light as the planet went in front of it. One of the stars is dimmer than the other and this too causes dimming of the brighter star’s light. Using these two effects and also knowing the radial velocity of the stars, the mass of the stars and the planet can be calculated. It is found that Kepler-16b is denser than Saturn, containing many heavy elements. It completes one orbit in 229 days. The masses of the stars, Kepler-16A and Kepler-16B, are 69% and 20% the solar mass, respectively. They orbit each other in 41 days. The three objects lie on the same plane, suggesting that they were created from the same cloud of gas and that Kepler-16b is not a captured planet.
The report came out in the journal Science’ today.
According to a huge announcement by the European Southern Observatory, more than 50 alien planets discovered by its telescope could harbour life. Out of these 50, 16 are so-called super Earths’, or planets that are similar to our own, but bigger.
The Goldilocks Zone
Earth is unique in the sense that it is a rocky planet, contains water in liquid form and is at an optimum distance from the host star. This allows the temperature to be within habitable range, as well as supports diverse weather conditions. These are the signs that astronomers were looking for while scouring the sky with the exo-planet hunting telescope. Sixteen of the potentially habitable 50 were declared to be Earth-like.
Amongst these 16, one of the planets caught the astronomers’ attention. This Super-Earth, called HD 85512b, orbits its star within the habitable region a narrow region around the star where conditions could be optimal to support known forms of life.
Finding an Alien Planet
The ESO’s instrument of pride is the High Accuracy Radial velocity Planet Searcher (HARPS) telescope. The HARPS telescope is more a spectroscope than a conventional telescope. It measures changes in the spectral signature of a planet-star system. This simply means that the light intensity and wavelength both change and tracking these gives hints of a planet orbiting a star. Accurate measurements can give the mass of the planet, and sometimes, even the composition.
Planets tug on stars due to gravity and this makes the star wobble slightly. These radial velocity signals’ can be easily picked up by HARPS. The enormous resolution of HARPS ensures that it can even detect the slightest of wobbles.
HD 85512b is located pretty close by too. It is only 35 light-years away and is estimated to be 3.6 times more massive than the Earth. Orbiting in the habitable region’, the super-Earth could possibly support liquid water.
Only further studies will reveal whether this super-Earth is indeed inhabited by beings as complex as those found on Earth. Have we just found the home of our intergalactic neighbour?
The best hidden player in a cosmic game of hide-and-seek has just been given away by its own gravitational attraction. For the first time ever, scientists have identified an invisible alien planet by just noticing the gravitational attraction it exerts on another planet, which has been observed. The game was won by the NASA’s Kepler Space Telescope.
An Alien World
Kepler detected one alien planet as it made a transit across the star it orbits. However, it was noticed that the transit started five minutes early and ended five minutes later than expected. This could only mean that another planetary body tugs on this planet speeding up or delaying its orbital speed. The observed planet has been named Kepler 19b and the unseen planet, Kepler 19c. This is the first time this technique known as transit timing variation or TTV has been used to figure out the existence of an exoplanet. The planetary system is 650 light years away in the constellation Lyra.
Sarah Ballard of Harvard-Smithsonian Center for Astrophysics explains it in naughty-next-door-kid jargon:
It’s like having someone play a prank on you by ringing your doorbell and running away. You know someone was there, even if you don’t see them when you get outside
What about Kepler 19c?
Almost nothing is known about Kepler 19c, except for the fact that it exists. Generally, all planets fall in two categories rocky planets and gas giants. Kepler 19c can be a rocky planet with an orbital period of about 5-7 days (i.e. it is really close to the host star, but light) or it can be a gas giant with an orbital period of 100 or 200 days (i.e. it is far off, but very massive). Both types would be able to exert similar gravitational influence on Kepler 19b.
Kepler 19c hasn’t been seen transiting the parent star, suggesting that the planes of orbit of Kepler 19b and 19c are oblique to one another. Kepler will keep looking. Kepler has done an excellent job in detecting exoplanets, detecting as many as 1235 planets in its first four months of operation.
The excitement and toil of such a search is the same as that of a murder mystery investigation, but happily without a victim. Did you just say, Elementary…? It is not!